Yellow-footed Rock Wallaby Husbandry Manual - Marsupial and ...

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Yellow-footed Rock Wallaby Husbandry Manual - Marsupial and ...

Yellow-footed

Rock Wallaby

(Petrogale xanthopus xanthopus)

Husbandry Manual

Adrienne Miller, Studbook Keeper

Roger Williams Park Zoo, Providence, RI

August 2001

Cover photo taken by Russell Menard, Coturaundee Range, NSW, Australia


Table of Contents

I. History of the Species ...................................... 4

A. Classification & Status ............................................. 5

-Yellow-footed Rock Weasel? ............................ 5

-Shifting Status ................................................... 5

B. Wild Population ........................................................ 8

-Andu ...................................................................8

Aboriginal rock painting............................ 9

-History of the Wild Population .......................... 9

-Current Population ............................................ 12

Distribution map....................................... 13

-Current Threats to the Population ..................... 14

C. Captive Population ................................................... 16

-Adelaide Zoo Colony ........................................ 16

Adelaide Zoo exhibit ................................ 17

-North American Population .............................. 18

II. Natural History......................................... 20

A. Description of the Species ....................................... 21

-Species at a Glance ........................................... 21

-Physical Description ......................................... 22

-Behavior ............................................................ 23

B. Habitat ...................................................................... 27

-Description of the Habitat ................................. 27

Cross section of habitat ........................... 28

Typical habitat (Gap Ranges, NSW) ........ 29

-Habitat Use ........................................................ 30

C. Wild Diet .................................................................. 32

-Diet in the Wild ................................................ 32

List of plants eaten in the wild ................. 34

-Water Dependency ........................................... 35

D. Reproduction ........................................................... 36

-Reproductive Biology ....................................... 36

-Parental Care ..................................................... 37

-Joey Development ............................................ 37

Joey feeding chart ................................... 40

Joey growth chart ................................... 41

Growth statistics ..................................... 42

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E. Research Projects .................................................... 43

-Habitat Reclamation (New South Wales) ....... 43

Coturaundee study site ........................... 44

Fecal pellet count / Radiotracking ......... 45

-Reintroduction (South Australia) .................... 46

Leigh Creek brochure ............................ 48

Aroona Dam overview ........................... 49

Rock wallaby trap / Bagged wallabies ... 50

Rock wallaby processing ........................ 51

III. Husbandry & Care............................................. 52

A. Husbandry ................................................................ 53

-Exhibits & Holding ............................................ 53

-Social Grouping ................................................. 54

-Mixed Species ................................................... 54

-Captive Diet ...................................................... 54

B. Veterinary Care & Handling .................................... 56

-Parasites ............................................................ 56

-Common Diseases ............................................. 56

Diseases & Illnesses Chart ....................... 57/58

-Chemical Immobilization .................................. 59

-Identification ..................................................... 59

-Handling ........................................................... 59

-Transporting ...................................................... 62

IATA container regulations ..................... 64/65

IV. Bibliography & Sources ................................ 66

A. Bibliography ............................................................ 67

B. Internet Sites Referenced ......................................... 72

C. Sources .....................................................................73

Drawing by Leigh Creek School student, South Australia

Zootimes Vol. 14, No. 3, October 1997

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History of the

Species

4


1. A. CLASSIFICATION & STATUS

YELLOW-FOOTED ROCK WEASEL?

The yellow-footed rock wallaby (Petrogale xanthopus Gray) was first described from specimens

collected in the Flinders ranges by naturalist Frederick Strange in the late 1840s or early 1850s

(Copley, 1983). He sent two specimens to the British Museum of Natural History where Director

and taxonomist J.E. Gray described it as a new species of wallaby in the genus Petrogale [rock

(petro) weasel (gale]. He gave it the species name xanthopus [yellow (xantho) footed (pus)] in

1855 (Lim et al, 1987). Wilson and Reeder (1993) reference a limited use of xanthopygus.

Of the ten distinct species in the genus Petrogale, they are one of four with 22 chromosomes.

The very closely-related Petrogale x. celeris (the Queensland yellow-footed rock wallaby) is

considered a conspecific, as they share the same derived alleles at several loci and a common

karyotype not found in any other rock wallaby species. The other species in this group are

Petrogale rothschildi and Petrogale persephone (Lim et al, 1987; Strahan, 1995).

The International Zoo Yearbook (IZY) referred to the Petrogale species as the order Marsupialia

until 1995 when it was reclassified as Diprotodontia (Olney, 1997).

Petrogale x. xanthopus is also commonly referred to as the ring-tailed rock wallaby, and the IZY

called it the Southern yellow-footed wallaby in its 1998 edition to separate it from the

Queensland subspecies, Petrogale x. celeris. There is also a reference to it being referred to as

the yellow-legged rock-kangaroo (McKay et al, 1997).

SHIFTING STATUS

The wild status of the yellow-footed rock wallaby has been in constant flux as new information

is obtained. The constant change is because they may be locally very common in some areas, but

of increasing rareness in much of their former habitat. The best description of its status is that it

is “considered to be potentially vulnerable to extinction” (Pope et al, 1996). Accenting the

positive, they can be referred to as relatively abundant in suitable habitat.

The International Zoo Yearbook listed Petrogale xanthopus as "II" (forms whose status should

be watched and for which protective measures should be taken wherever practicable) in its 1962

edition. It was listed as "Rare" (originally defined as species in danger of extinction or extremely

rare in their natural habitats, but later defined as "Taxa with small world populations that are not

at present "Endangered" or "Vulnerable", but are at risk. These taxa are usually localized within

restricted geographical areas or habitats or are thinly scattered over a more extensive range) from

1963 to 1974 (although the 1966 IUCN Red Data Book classified it as 'inadequately known'

during that time). It was listed as Vulnerable (taxa believed likely to move into the "Endangered"

category in the near future if the causal factors continue operating. Included are taxa of which

most or all the populations are decreasing because of over-exploitation, extensive destruction of

habitat or other environmental disturbance; taxa with populations that have been seriously

depleted and whose ultimate security has not yet been assured; and taxa with populations that are

still abundant but are under threat from severe adverse factors throughout their range) from 1975

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through 1981. It was listed as Rare again from the 1982 edition to 1995. It then became "Lower

Risk near threatened" (species in the "near threatened" subcategory of the Lower Risk category.

Taxa in this subcategory are "near threatened" in the sense of being close to the threshold of the

Vulnerable category) in 1997 (Olney, 1997).

The species was excluded from the 1984 IUCN Red Data Book because "Recent surveys funded

by WWF Australia have shown there to be a substantial population of this species in the Flinders

Range, South Australia, with evidence of occurrence at over 170 separate sites. It also occurs in

the Gawler Range in South Australia, extending into the Barrier Range in New South Wales and

the Grey Range in Queensland (note: this last reference is to Petrogale x. celeris). It is fully

protected over its range and there is no evidence of a threatened status (Thornback & Jenkins,

1984)."

In 1988, the yellow-footed rock was listed by the NSW National Parks and Wildlife Act as

Schedule 12 Part 4 "Fauna in Imminent Danger of Extinction due to the fact that it occurred in

such low numbers that it was believed to be in imminent danger of extinction and survival was

dependent on special protective measures" (Lim et al, 1992).

In the "Endangered Fauna (Interim Protection) Act 1991", the yellow-footed rock wallaby was

considered Schedule 12 Part 1 "Threatened". This was based mainly on assessments of the New

South Wales population having a "reduction of populations to a critical level, drastic reduction

and modification of their habitat, a species in danger of extinction..." Species in Schedule 12

were given greater protection than many other protected species (Lim et al, 1992).

The 1992 Australasian Marsupials and Monotremes: an Action Plan for their Conservation

classified Petrogale xanthopus (no subspecies indicated) as Potentially Vulnerable with a note

that the population in New South Wales was classified as Endangered. Their description of

Potentially Vulnerable was one whose population appeared stable but faced pressures that could

lead the species to become Endangered. Endangered was defined as a species in danger of

extinction and whose survival is unlikely if the causal factors continue operating. This document

also indicated that 50-90% of its geographic range had declined since European settlement

(Kennedy,1992).

The 1996 edition of the IUCN Red Data Book listed Petrogale x. xanthopus as Vulnerable C2a

(a population that is not endangered but is facing a high risk of extinction in the wild in the

medium-term future, population estimated to number less than 10,000 mature individuals

showing a continuing decline observed, projected, or inferred, in numbers of mature indiviuals

and population structure in the form of a severely fragmented population estimated to contain

more than 1,000 mature individuals) (Baillie & Groombridge, 1996) and it remains so listed.

The Australian Species Management Plan (ASMP) listed it as Category 3(1) species in 1998. A

Category 3 is a monitored species with medium level regional management covered by a

studbook to which member institutions may refer and/or by recommendations by the TAG. The

(1) indicates it is being moved toward being a Category 1 species, a Cooperative Conservation

Program Species with a high level of regional management with the captive population managed

as part of a wildlife agency species recovery program (Barlow, 1998). It is currently listed by the

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ASMP as a Management Level 1a (high intensity genetic and demographic management aimed

at maximizing gene diversity, minimizing inbreeding and controlling reproductive rate. Programs

are overseen by a species coordinator who prepares a strategic plan for the population and annual

breeding recommendations, which institutions make a formal commitment to follow. This level

is equivalent to current Category 2 management, and to the management applied to captive

populations of most current Category 1 species).

The New South Wales population is classified as Endangered under the NSW Threatened

Species Conservation Act 1995; Schedule 1 (Sharp, 1998).

The US Fish & Wildlife Service classified Petrogale xanthopus (indicating no subspecies) as

Endangered on June 4, 1973 and it remains so listed.

Although there is no official recovery plan for the species in South Australia, there is work being

done by the Department of Environment, Heritage and Aboriginal Affairs (DEHAA) in the

conservation and management of yellow-footed rock wallabies in the wild there. There is a

recovery plan for the New South Wales wild population (Johnson, 1998). There is also a

reintroduction project in South Australia. For further information on these projects see the

"Research Projects" section.

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I. B. WILD POPULATION

ANDU

Rock wallabies are believed to have their origin on the pre-Cambrian part of the continent, the

Australian Shield (Lim et al, 1987; Strahan, 1995). The recorded history of Australia also begins

with these earliest-known rocks in the southwestern corner of Western Australia. Making up a

series of plateaus rising some 500 meters, they extend from the Darling Range in the West to the

Musgrave Ranges southwest of Alice Springs in the East. Most of this land has not been under

water for 700 million years, but in times when the sea covered much of the present area of

Australia, these regions would have appeared as islands (Shaw, 1984).

The earliest known records of the Petrogale genus are in the Pliocene era when the land was

becoming drier with more open vegetation. This early rock wallaby was probably a species of the

forest margins, a habitat similar to the current one of the Proserpine rock-wallaby (Petrogale

persephone). Petrogale perhaps evolved from a rainforest ancestor of Thylogale as the rainforest

vegetation retreated, opening up a new niche of rocky cliffs and gorges that this developing

species exploited (Maynes, 1989).

The Aboriginal people in South Australia's Flinders Ranges today are referred to as the

Adnyamathanha (Hills People) and have had a long association with the yellow-footed rock

wallaby which they called "Andu". The rock wallabies were hunted for their meat, pelts which

were made into bags and cloaks, and tail sinew which was used for sewing or making nets

(Sharp, 1994). The standard means of hunting was with either a throwing waddie or a boomerang

(Lim et al, 1987). The Wailpi people, and probably also the Adnyamathanha, dug pits or built

traps along frequently used wallaby paths. These traps could catch up to 30 animals at a time

(Sharp, 1994). The remains of stone-lined pit traps have been found below Attunga Bluff, and

the remains of an enclosure can still be seen near Terrapinna waterhole. In the Olary Hills there

are remains of low rock walls along wallaby paths, presumably to hide hunters with spears.

Although any tribe member could hunt the rock wallaby, the butchering and distribution of the

meat was under strict control of only the initiated men of the group. When tribal initiations

ceased in the 1940s, leading to a decline in those qualified to prepare and distribute the meat, it is

unlikely that yellow-footed rock wallabies were used as a food resource after this time (Sharp,

1994). The northern Dieri people obtained yellow-footed rock wallaby skins from the Wailpi and

used them as coverings for corpses (Lim et al, 1987).

It is thought that at one time, the ancesters of the current yellow-footed rock wallaby formed one

continuous population from central South Australia up into Queensland and as far as the great

Dividing Range (Strahan 1995). However, fragmentation in the population occurred as a result of

the introduction of feral animals such as the predatory foxes and cats and resource competitors

such as goats and sheep. Land-clearing compounded the problem by removing the animal's

natural dispersal routes. The Queensland population has actually become genetically distinct

from their southern counterparts remaining in New South Wales and South Australia. A similar

process is continuing on a much smaller scale in their remaining habitats. Separated populations

are becoming genetically distinct from their neighbors, even in populations separated by as little

as 70 km, probably as a result of inbreeding, necessitated by the fragmented colonies. This is

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also causing small isolated colonies to become locally extinct because of lack of the possibility

of recruitment from other colonies and predation of young by the introduced predators (Sydney

University Website, 1999).

This Australian Aboriginal rock painting of a wallaby is approximately 5,000

years old. Nomads mixed pulverized rock with water and used fine feather or human-hair

brushes for the delicate cross-hatching strokes. Twigs, frayed at one end by chewing, traced

broader lines. Tribal elders once passed down this art form to their young initiates. Photo and

information courtesy of Stanley Breeden, Queensland, Australia.

HISTORY OF THE WILD POPULATION

South Australia

Although the Aboriginal people had known and hunted the yellow-footed rock wallaby for

thousands of years, and it was an integral part of their legends and traditions, the species was not

officially recognized by European science until two specimens were collected in the 1850s from

the Flinders Ranges, South Australia, by Frederick Strange. The first European to see Petrogale

x. xanthopus was Edward John Eyre ten years earlier during his exploration of the Flinders

Ranges in 1840 when he recorded seeing large numbers at Mt. Aroona, near what is now Leigh

Creek (Lim et al, 1987).

Originally found in large groups of sixty or seventy, and in some places even referred to as

"virtual plague proportions", their population numbers quickly dropped as rock wallaby shooting

became a favorite sport with European colonists. This hunting was actually encouraged during

the 1880s and 1890s (Lim et al, 1987). They were still seen in small droves of 60-70, or 20-30

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where hunting was prevalent, but their overall numbers had already begun to decrease in the

early 1880s (Copley, 1983).

The best sport we had was in firing at the rock-wallaby from the seat of the buggy,

and watching them fall down the cliffs. Fourteen we saw fall, some were wounded,

but before reaching the bottom were pretty well dead. One in particular had a soft

and lucky fall and came to die at our horses' feet. We were indeed loathe to leave

so pretty a spot. We gazed and feasted our eyes on nature's handiwork.

(The Areas Express and Farmer's Journal, 1 December 1883) (Lim et al, 1987)

..."the rock wallaby is by far the most abundant of animals, and yet it is a

much persecuted creature. Rock wallaby shooting is a

favorite sport with all classes of colonists."

(Fountain, 1907) (Lim et al, 1987)

High prices were paid for the rock wallaby skins. Some areas offered scalp bonuses or bounties

between fourpence and a shilling per scalp. Hundreds of skins were exported from Adelaide to

London in 1894 (Lim et al,1987). There is reference to 300 being killed in a single day for this

bounty (Copley, 1983).

Up until 1910-15, the yellow-footed rock wallaby was still sometimes seen in group of 20 or 30,

but their population decline was alarming enough that in 1912 the South Australian Parliament

enacted an Animals Protection Act forbidding the taking or killing of rock wallabies and the sale

of their skins. Regardless, between 1915 and 1925 their population continued to decline rapidly.

In 1924, rock wallabies were still being slaughtered in South Australia, with their pelts being

disposed of in neighboring states. This led Professor Wood Jones, one of Australia's great

zoologists to state:

"Although a totally protected animal in this State, this protection is not extended

to it by certain of the States upon the borders of which it lives. It is therefore not

to be wondered at that pelts of the animal are disposed of in markets of States

other than South Australia; even though the animal was obtained within the

geographic boundaries of our own State. Petrogales xanthopus is a fitting

example of an animal which needs sanctuary for its preservation and more

stringent legislation efforts to check its slaughter."

(Copley, 1983; Lim et al, 1987)

In addition to the exploitation for their pelts, competition from introduced herbivores such as

goats and rabbits and predation by introduced foxes and cats caused their population to decline

even further. By 1930, they were rarely seen at all (Lim et al, 1987), and from 1924 to early 1970

there were few significant records of sightings and no research was undertaken (Copley, 1983).

Pastoral activities which began in the Flinders Ranges during the 1850s had drastic effects on the

native flora and fauna, including the yellow-footed rock wallaby in some areas. Mining activities

also disturbed rock wallaby colonies especially during the 1860s-1880s, however rock wallabies

10


are still present in most mining areas that are known to have had colonies, although these may be

recolonization of exterminations (Copley, 1983).

At least 24 colonies are known to have become extinct in South Australia, representing at least

half of the known colonies in the Olary Hills and Gawler Ranges regions (Maxwell et al, 1996).

Others estimate it higher at over 30 known colony extinctions since European settlement (Lim et

al, 1987). In addition, 50-90% of its geographic range has declined since European settlement

(Kennedy, 1992).

New South Wales

In 1966, the presence of Petrogale x. xanthopus was confirmed in the Coturaundee Range in

New South Wales. It had never been officially recorded in New South Wales prior to 1966,

although there had been unconfirmed sightings (Sharp, 1998) and a 1924 range description that

placed Petrogale x. xanthopus in New South Wales. For these reasons, this official find was

recorded as a "rediscovery", although some feel it would have been more correct to call it a

"range extension" (Lim et al, 1987).

Ground and helicopter surveys in 1972 concluded that the species was confined to a 70 by 10 km

area between White Cliffs and Mootwingee National Park. Further surveys in 1978-79 by the

National Park and Wildlife Service found an even more restricted distribution, the only

remaining NSW populations existing along the Coturaundee and Gap Ranges (in Mootwingee

National Park) some 10 km apart and 150 km northeast of Broken Hill. This survey also found,

through the discovery of old fecal pellets, that the past distribution in New South Wales may

have been wider than previously believed (Lim et al, 1992).

The Coturaundee Range wallabies were given some protection by the establishment of the 6,688

hectare Coturaundee Nature Reserve in 1979. However, three of the seven known groups are

actually outside the reserve boundaries. In 1983, the 68,900 hectare Mootwingee National Park

encompassed the rock wallabies in the Gap Range. Here also, the three wallaby sites are all close

to the reserve boundary. The result is, although the two known colonies have been protected,

many of the animals actually live outside the reserves, and possibly all of them sometimes forage

outside of the boundaries. (Lim et al, 1992; Sharp, 1998).

Rock wallabies were historically reported in the northwest corner on the outskirts of Tibooburra

in the 1960s. As late as 1983, they were also listed as occurring in NSW's Barrier Range, but

there are no rock wallabies in the Barrier Ranges today (Lim et al, 1987). No known populations

exist outside the Gap and Coturaundee Ranges (Maxwell et al, 1996).

Recent genetic studies indicate that this NSW population should be considered an Evolutionary

Significant Unit (ESU), or a population with its own distinctive genetic characteristics (Sharp,

1998). Such a population should receive high conservation priority.

Queensland

In 1922, the closely-related Petrogale x. celeris (celeris = quick [Lim et al, 1992]) was found in

southwest Queensland. Petrogale x. celeris is slightly smaller than Petrogale x. xanthopus, with

less distinct body markings (Sharp, 1994). Studies have shown this to be a separate, although

11


very closely-related, sub-species. They share the same derived alleles at several loci and a

common karyotype not found in any other rock wallaby species (Lim et al, 1987). However,

populations from South Australia and Queensland have phylogenetically distinct mtDNA,

supporting the idea that the two populations have been isolated, at least with respect to maternal

gene flow, for an extended period, resulting in their classification as two as evolutionary distinct

sub-species (Pope et al, 1996).

CURRENT POPULATION

The yellow-footed rock wallaby is a secretive animal, making population size estimates very

difficult. Aerial surveys from helicopters appear to detect more animals than do ground surveys,

but a large proportion may still be missed. It is estimated that only 17-22% of the animals present

are ever actually seen (Lim et al, 1992).

Although early settlers commented on the large numbers of this species in the Flinders Ranges

with mobs of 40-50 animals regularly seen until the early part of this century, over the past 15

years only eight colonies in South Australia have had more than twenty rock-wallabies recorded

at them, and even then, not on a regular basis. As the species is continuing to decline, it should

be considered threatened within the state (Copley & Alexander, 1997).

Petrogale x. xanthopus is found in several locations in South Australia but in only two locations

in New South Wales. By comparing recent survey and census data with previous information, it

is believed that P. x. xanthopus has maintained most of its known geographic range within South

Australia. However, its relative abundance has declined and 15% (35) of a total of 229 recorded

colonies have become extinct since European settlement. Eight of these colony extinctions have

happened over the last 25 years, with three of them since 1981. Counts at nearly all monitored

colonies are small. Isolated colonies that occur in relatively small areas of suitable habitat have a

low probability of survival in the short-to-medium term, and most of these extinctions occur in

colonies occupying such habitat. However, colonies which lie adjacent to each other along

connecting ridge systems may allow interchange of animals, increasing the effective population

size and chance of long-term survival (Copley & Alexander, 1997).

Of the 201 currently known colonies in South Australia, 187 of these are located in the Flinder's

Ranges where the rock wallaby is still widespread and locally common. Seventy of these

colonies occur within conservation areas. Total Flinders Ranges population was estimated as

6,407 – 7,700 in 1981 (Lim et al, 1987). In the rest of South Australia, there are seven colonies in

the Gawler Ranges of the Eyre Peninsula with a 1981 population estimate of 274 – 332, and

another four colonies (seven per Copley, 1983) in the Olary Hills with an estimated population of

206 – 260 (Lim et al, 1987). More recently, Sharp (1994) estimated 7,000 – 10,000 remaining

across their entire range (Sharp, 1994). In 2000, they were estimated at less than 5,000 (S.

Lapidge, pers. com.)

The colonies in the Gap and Coturaundee Ranges appear to be the only extant populations

existing in New South Wales and population estimates for yellow-footed rock wallabies there

was 183 – 232 (Lim et al, 1987) a decade ago, and a more recent estimate of 100-150 animals

(Sharp, 1998).

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Distribution of the yellow-footed rock wallaby (Petrogale x. xanthopus) in Australia.

(adapted from Lim, 1992)

1. Gawler Ranges (South Australia)

2. Carriewerloo (South Australia)

3. Flinders Ranges (South Australia)

4. Olary Hills (South Australia)

5. Gap and Coturaundee Ranges (New South Wales)

6. Adavale-Blackall (Petrogale xanthopus celeris) (Queensland)

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CURRENT THREATS TO THE WILD POPULATION

Although now legally protected from hunting, there are still a variety of potential threats for all

of the populations of yellow-footed rock wallabies. Primarily these are predation by feral foxes

and cats and competition for food from feral goats and rabbits. Habitat degradation may also play

an important role (Sharp, 1998).

Rock-wallabies are highly vulnerable to predation, especially juvenile animals which vacate the

pouch at an early developmental stage and a small size of about 1 kg (Sharp, 1998). At-heel life

is only about 10 days, and this results in small, inexperienced animals left on their own, adding

more danger to an already precarious life stage. In the Coturaundee Range in 1998, the author’s

husband was able to get within 8 feet of a juvenile P. x. xanthopus and observe it, while it

observed him, for almost a minute before it finally bolted.

The most significant predator is the introduced fox. Although they cannot bring down an adult,

these predators can easily kill a juvenile left unattended by its mother, thus reducing the numbers

of wallabies reaching maturity (Sharp, 1994). The fox is an excellent rock climber and is often

considered to have contributed significantly to the wallaby’s decline. There is evidence for this

in the Gawler Rangers, where the rock wallaby population decline coincided with the arrival of

the fox shortly after 1910 and its rapid proliferation during the 1920s. However, in the Flinders

Ranges, the major population decline preceded the arrival of the fox, and the species is thriving

in areas where foxes have been common for 60-70 years. Explanations include the inaccessibility

of the wallaby habitat, the ready availability of alternative small prey such as rabbits and mice

and the large size of mature yellow-footed rock wallabies (Copley, 1983). However, there were

two reports of adult female rock wallabies being taken by a fox, one in New South Wales and the

other in the Flinders, as well as reports of carcasses that appeared to be fox-kills (Lim et al,

1992).

Goats, introduced with the first Europeans, have been implicated in the decline of rock wallabies

as they thrive in the same rocky habitats, although the rock wallaby's major decline occurred in

the 1880s and 1890s, whereas goats were not common in the region until the early 1940s,

reaching nuisance proportions in the 1960s (Johnson et al., 1989). In New South Wales, goats

and rock wallabies have 40-75% of their dietary components in common, with the greatest

overlap during periods of drought. In addition, the competition for shelter is critical, and goats

have been observed to physically evict rock wallabies from their cave shelters. (Copley, 1983). If

their numbers are high enough, goats can denude an area of appropriate vegetation in a very

short time. During her visit to rock wallaby sites in New South Wales, the author was highly

amazed by the effects of the goats. There were areas with high goat populations where plant

seedlings were negligible, and nothing was growing to replace older plants when they died. The

goats were even destroying Aboriginal carvings and paintings by their constant rubbing against

the rock surfaces. According to Lim et al (1992) a possible future management option is the

erection of a goat-proof fence around the New South Wales colonies. However, there is no

evidence that competition between the two has led to local extinctions.

Although dingoes are often presumed to be major predators of rock wallabies, in reality their

impact is probably minimal. The dingo is not considered a significant threat because it cannot

climb well enough to take them in their rocky habitat.

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Some believe the rock wallaby appears to be regularly hunted by the wedge-tailed eagle and on

one occasion, seven eagles were seen circling over a colony, making periodic swoops at the

wallabies as they ran across the rock face (Strahan, 1995). In another instance, a wedge-tailed

eagle was seen to knock a rock wallaby off its feet but it was able to dive into a fissure in the

cliff face, as did its companions, while the eagle made several passes before going on its way

(Domico, 1993). Lapidge (1997) noted that a pastoralist at Wallaby Rock claims that almost half

of yellow-footed rock wallaby joeys in that colony were taken by wedge-tailed eagles (Lapidge,

1997). Adult rock wallabies are generally too agile and live in too much cover to be common

prey for the eagles (Copley, 1983), although they have been seen feeding on remains (Lim et al,

1992).

Feral cats, introduced by the Europeans and weighing up to 16.1 kg, are capable of taking young,

unattended wallabies and are quite agile enough to traverse the rocky habitat, but it is unlikely

that they have contributed significantly to the species decline (Lim et al, 1992).

Snakes may cause some mortality, as the large pythons sometimes share the shelters with the

wallabies, and even a small venomous snake could kill an adult. Snakebite was not ruled out as

the cause of death for an adult yellow-foot found dead at the Aroona Dam reintroduction site

soon after release in 1996.

Introduced rabbits (Oryctolagus cuniculus) are abundant near most known rock wallaby

populations. However, they only occasionally utilize the same habitat, living instead on the

plains and along creek beds where there is a sufficient soil depth for burrowing. When their

populations do overlap, it has been found that 50% of their dietary components are in common,

so they may compete directly for food, especially in times of drought (Copley, 1983). Rabbits

can also have significant impact on plant availability by eating seedlings, preventing

regeneration, and by ring-barking older plants (Lim et al, 1992).

Euros (Macropus robustus) occupy the same rocky ranges as do the rock wallabies, but these

species have usually co-existed. The Euros eat mostly grasses, obtained on and away from the

ranges, whereas rock wallabies eat a variety of grasses, forbs and browse. But the competition

for shelter sites may increase the pressure for shelter on the rock wallaby (Copley, 1983).

Numbers of rock wallabies fluctuate in response to annual rainfall patterns (Copley & Alexander,

1997). The effect of drought is compounded by increased competition for food with introduced

herbivores such as the goat. During a moderate drought in New South Wales in 1982-1983,

numbers of yellow-footed rock wallabies dropped by 60%. After the drought broke, the

population soon recovered where goats were controlled, but remained depressed in areas where

there was no control (Strahan, 1995).

15


ADELAIDE ZOO COLONY

I. C. CAPTIVE POPULATION

Most appropriately, the yellow-footed rock wallaby is the faunal emblem of the Adelaide Zoo as

their records indicate a captive colony has been in continuous residence there since 1883. For

most of its existence it has been totally self-sustaining. The origins are somewhat confused by

nomenclature regarding the original donation in 1883 where acquisitions were recorded as "rock

wallabies (Petrogale xanthopus)", but annual inventories were recorded as "rock kangaroos

(Petrogales penculata [a presumed misspelling of Petrogale penicillata])." In 1897 the term

"rock kangaroo" was dispensed with entirely. The evidence of the donor's South Australian

address, however, supported the conclusion that these were indeed Petrogale xanthopus

(Hornsby, 1980).

The fourteen rock wallabies donated in 1885 are usually considered the foundation of the

continuous Adelaide Zoo colony. Between 1885 and 1915, twenty-five more animals were

donated to the captive colony. In 1938, it was reported that great difficulty in obtaining new

specimens had been experienced and their present individual (a female) was the only one they

had been able to acquire in twenty years. The next addition wasn't until a female was purchased

in 1949. The only additions from external sources for quite a while were a wild-born male in

1975 and a female a year later (Hornsby, 1980). Six wild males from the Flinders Ranges have

been added in the last decade (S. Lapidge, pers. com.).

The size and progress of the colony during its initial years are unknown because acquisitions

were recorded but births and deaths were not. Stock inventories were discontinued after 1892

and not reinstated until 1942. Zoo births were recorded as part of the Annual Reports of 1910-

1917, and resumed again in 1929 without further interruption (Hornsby, 1980). According to

Suzy Barlow, former Australian studbook keeper for Petrogale x. xanthopus, the first captive

breeding occurred in the 1920s (Barlow, 1997).

The population reached a peak of 62 animals in 1966 caused by an exceptionally high breeding

rate. It is believed that the wild breeding response of accelerated breeding rates when animals

aggregated during "good" climactic years carried over into the captive population. Between 1963

and 1971, 52 individuals were sent to other institutions, although the only surviving colony of

those dispositioned at this time is at Penola Station Fauna Sanctuary in South Australia. Due to

deaths and unexplained male sterility, the Adelaide colony was reduced to a single pair in 1975.

Luckily, the female was carrying a pouch young, and again, the colony began increasing. This

female was especially interesting in that she illustrated possible inhibition of breeding in

subordinate females as she did not breed until she had been left as the sole surviving female

(Hornsby, 1980).

16


All current captive animals in Australia and North America have descended from these Adelaide

Zoo individuals (Barlow, 1997). The yellow-footed rock wallaby has been part of an Australian

Regional Management Plan since 1980.

The Adelaide Zoo exhibit features a rock scramble and hide cave.

17


NORTH AMERICAN POPULATION

The first record of possible captive Petrogale x. xanthopus in North America are 1916-17

imports of 2.2.1 animals by the Bronx Zoo. According to their records, four of these individuals

came from Ellis S. Joseph, New South Wales, Australia, and one from a private individual's trip

to Port Elizabeth, Africa. Only one female of this group is actually referred to as a yellow-footed

rock wallaby (ringed tail), Petrogale xanthopus. She apparently arrived with a female joey in the

pouch, although this animal is recorded as a "young ring-tailed wallaby". The rest are also

referred to as "ringed-tail wallaby", with no scientific name, except the one from Africa who is

recorded only as a "rock wallaby". There were apparently offspring from these animals through

1929. Many animals were shipped back to Ellis S. Joseph in 1924 and 1926, and the last animal

died in 1936. Collins (1973) notes a longevity record of 12 years, 2 months (July 14, 1917, to

September 25, 1929) for an animal held there during this time.

During a similar time period, the National Zoo imported 1.2 Petrogale xanthopus (ring-tailed

rock wallaby) from Lutz Ruhe on 11 August 1921. The two females died in July of 1922 and the

male died in Ocotber, 1922. They apparently did not reproduce.

As the Queensland colony of the subspecies Petrogale x. celeris was not "discovered" until

1922, it is presumed that both the Bronx Zoo and the National Zoo collections were Petrogale x.

xanthopus, but these individuals are not included in the studbook data as it cannot be proven.

There were apparently no surviving offspring from these groups, so genetics of the current

population are not affected by their exclusion.

The first International Zoo Yearbook (IZY) mention of Petrogale xanthopus (the IZY does not

list by subspecies except in the 1998 edition, when it separated Petrogale xanthopus [yellowfooted

rock wallaby] from Petrogale x. xanthopus [Southern yellow-footed wallaby]) in North

America was 2.0 held at Eureka (believed to be Sequoia Park Zoo, Eureka, CA) in the 1962

edition. The zoo was unable to find any records to support this, and there was no other IZY

references to Eureka.

1.1.1 were recorded to be in Parque Zoologico, Santa Domingo, Dominican Republic, in the

1977 edition of IZY (Olney, 1978). I received no response to my inquiry to Parque Zoologico

regarding these individuals, and there was no further mention in IZY of the species in this

institution.

The 1986 IZY edition had the start of the first continuous North American records when San

Diego Zoo recorded a single male for 1983 and Los Angeles Zoo recorded 3.0 for 1984. This

1986 edition also stated "all are captive bred" for 1983 and "most are presumed captive bred" for

1984 (Olney, 1986).

The first captive births in North America recorded in IZY were at the Los Angeles Zoo in 1987

(Olney, 1989).

The first International Species Information System (ISIS) records for Petrogale x. xanthopus in

North America are a 1927 acquisition by San Diego Zoo. However, San Diego records indicate

this was Petrogale x. celeris and not Petrogale x. xanthopus. ISIS records of continuous

18


collections in North America begin in 1982 at the San Diego Zoo (2.0) and 1983 at the Los

Angeles Zoo (1.0).

The AZA Marsupial and Monotreme Taxon Advisory Group’s (M & M TAG) Regional

Collection Plan has designated Petrogale x. xanthopus as a future Species Survival Plan (SSP)

species. The current small North American captive population cannot support a geneticallyhealthy

population. However several zoos have expressed an interest in importing the species,

some hoping to hold colonies as large as 12 – 15 animals. Fortunately, one of the goals for 2000

of the Australian Species Management Program (ASMP) is to review and recommend exports to

the United States. One goal of the AZA M & M TAG is to foster cooperative efforts with the

Australasian Regional Association of Zoological Parks and Aquaria (ARAZPA) and

Environment Australia (EA) that would help promote imports by North American institutions as

well as cooperative conservation efforts. The first step toward this goal was a "Species Summit"

meeting of the three organizations held in March 2001 in Dubbo, New South Wales. Although

many Australian species were discussed at this summit, the yellow-footed rock wallaby was a

major focus. The meeting resulted in a better understanding of each organization's goals and

requirements and will hopefully result in the much needed imports required for a genetically

sound and sustainable North American population.

19


Natural

History

20


II. A. DESCRIPTION OF THE SPECIES

SPECIES AT A GLANCE

COMMON NAME yellow-footed rock wallaby

ring-tailed rock wallaby

yellow-legged rock kangaroo

SCIENTIFIC NAME Petrogale xanthopus xanthopus

WEIGHT Captivity: male 8.60 kg, female 6.50 kg

Wild: male 11 kg, female 3.0 kg

SIZE head and body length 480-650 (600 average) mm

570-700 (690 average) mm

STATUS ASMP: category 4(2)

IUCN: Vulnerable C2

USFWS: Endangered

NSW Threatened Species Act: Endangered

LIFE EXPECTANCY 11 years

DISTRIBUTION South Australia: Flinders Ranges, SA (vulnerable in southern and

central Ranges), Gawler Ranges (considered endangered

here), Olary Hills (5,000-10,000 estimate)

New South Wales: The Gap and Coturaundee Ranges (100-150 estimate)

HOME RANGE core area of about 30 hectares, prime areas occupied by females

INTERACTION low except between mother and young and mating pairs

HABITAT semi arid to arid, extensive rock outcrops with deep fissures and

caves

DIET wild – grass, herbs, leaves and fruit

ESTROUS CYCLE 30-32 days

GESTATION 31-32 days

POUCH

EMERGENCE 194 days

INTERIM

POUCH LIFE 7-10 days

21


PHYSICAL DESCRIPTION

The yellow-footed rock wallaby is appropriately named for its distinctive color and agile

behavior - yellow (xantho) footed (pus) rock (petro) weasel (gale) (Sharp, 1994).

Anyone who has seen this wallaby is impressed by its beauty. Its distinctive markings make them

one of the “most beautifully adorned” (Sharp, 1994) and “most charismatic” (Sharp, 1998)

members of the macropod family. Others call it "One of the most beautiful of Australia's species

of wallaby" (Lim et al, 1987) and "the prettiest and most colorful kangaroo of them all"

(Domico, 1993).

Famous for his 1863 work The Mammals of Australia, John Gould was so taken by the original

two specimens sent to the British Museum of Natural History that he referred to the yellowfooted

rock wallaby as "one of the finest species of the form yet discovered. Its large size and

rich color render it very conspicuous" (McKay et al, 1997). He also stated "of so fine a species I

have considered it desirable to give two illustrations." He then went on to encourage the

acquisition of living specimens for menageries and additional examples for museums (Lim et

al,1987).

The fur, soft, thick and long, is fawn-colored with a dark mid-dorsal stripe, distinct white muzzle

stripe, a reddish-brown patch behind the arm, a buffy-white side stripe and brown and white

crescent marks on its flanks. The closely-related Petrogale x. celeris lacks this white hip patch

(Le Seouf, 1926). The forearms, hind legs and feet are a rich orange. The ears are very large with

yellow hair covering the outside. The brownish-orange tail has a distinctive series of dark brown

rings ending in a dark brown bush. The tail coloring is quite varied between individuals, some

even have white tail tips. The individuals in the northern Flinders Ranges tend to be more vividly

colored then those in the southern ranges. Surprisingly, this brilliant coloration provides good

camouflage against the patches of sunlight and shadow on the red rocks of their habitat

(Kennedy, 1990; Lim et al, 1987), and may be considered as evidence of disruptive coloration in

a macropodid species (Croft, 1996).

One of the largest of the rock wallabies, the yellow-footed rock wallaby weighs between 6 - 9 kg

according to Sharp, 1998, and as large as 11 kg (Bach, 1998; Lim et al, 1992). Adult males

weigh an average of 8 kg and adult females weighing an average of 6 kg (Lim et al, 1987). The

adult body size ranges between 480-650 mm with the ringed tail 570 – 700 mm in length (Bach,

1998). Males attain more developed forearms and shoulder musculature than do females (Lim et

al, 1987).

Birth weight range is between 460 – 572 mg (Bach, 1998). Although adults exhibit sexual

dimorphism in body size and weight, this dimorphism is not significant until young are more

than one year old and weigh approximately 3 kg (Robinson, 1994).

The fecal pellets are long and cylindrical with a diameter of about one centimeter, tapered to one

end (Lapidge, 1997), forming a pointed "tail" seldom found in other species' pellets (Lim et al,

1992). Because their molars do not grind their food as finely as more specialized animals the

pellets have a much coarser texture, due to the loosely packed and coarsely textured plant

material, than those of other mammals in their habitat. The hard, shiny black mucus coat, typical

22


of other local Macropods such as the Euro, is not as pronounced, and old weathered pellets are

much "rougher" in appearance (Lim et al, 1987).

The yellow-footed rock wallaby, along with other rock wallabies living in arid areas and eating

grasses, has a curved tooth row. They also have a large premolar that may prevent any molar

progression, thus preventing the posterior teeth from occluding. The first, and sometimes the

second, molars sometimes get squeezed out from behind the premolar, allowing the posterior

molars to drift into occlusion. This does not always occur, and skulls have been found where the

first two molars are worn down to the gum and the posterior molars are prevented from

occluding (Sanson, 1989)

The teeth of the genus Petrogale have only moderate molar ridges in comparison with members

of the genus Macropus. This allows them to be intermediate browsers/grazers (Lim et al, 1987)

and able to take advantage of a wide variety of foodstuffs.

The external jugular is particularly large and the heart of Petrogale xanthopus is distinctive,

having features that differ from the typical eutherian heart as well as the heart of other

macropods:

-the moderator band (also called the “septo-marginal trabeculum”, a band of

cardiac muscle) is absent

-the right atrio-ventricular valve is quadri-cuspid

-the left atrio-ventricular valve has only two cusps (as in eutheria, but not other

macropods), and

-two pulmonary veins open close together into the dorcal wall of the left atrium

(as opposed to four in eutherians) (Gannon et al, 1989)

Both sexes can live to at least 10 years in the wild (Robinson, 1994), and the studbook data

indicates life span is similar in captivity. Longevity of 12 years, 2 months, 11 days was noted at

the New York Bronx Zoo for an unidentified subspecies of Petrogale xanthopus (Collins, 1973).

In a study at Middle Gorge, it was found that more than 60% of the population had a life

expectancy between three and six years, with the mortality rate of individuals over six years

being 90% yearly (Lim et al, 1992).

BEHAVIOR

Cat-like or monkey-like have been used to describe the two-footed precision of a rock wallaby

leaping along the edge of a cliff face. (Ride, 1970). Rock wallabies are able to perform these

amazing acrobatics along the rocky outcroppings of their habitat due to two physical adaptations

that set them apart from other wallabies.

First, their long tails are less tapered and more cylindrical than other macropods and are carried

arched over the back (Sharp, 1994) or trailing "like plumes" during leaps. They are used more for

balance than as a rudder as other wallabies use their tails. The tails are also seldom used as props

for sitting as other wallabies often do (Domico, 1993).

Second, the soles of the hind feet and toe pads are thickly padded and have coarse bumps, like

the off-road tires on a sports utility vehicle. In addition, the first four bones of the enlarged third

23


toe make up a greater proportion of the foot than in other kangaroos (Lim, 1987). The toenails

are shortened and barely extend beyond the toe pad. Additional traction is provided by a fringe

of stiff hairs surrounding the soles (Domico, 1993). This specialized foot, combined with using

their long flexible tail for balancing, allows the yellow-footed rock wallaby to move securely

over precipitous and broken rock faces (Lim et al, 1987).

Rock wallabies can jump vertically about 2 ½ times their own height, but they achieve even

greater heights by "cannoning" off upright surfaces. They can make leaps of more than 16 to 20

feet, landing on the smallest of surfaces. The short forearms of an alerted or fast-moving animal

are held stiffly in front of the body (Domico, 1993) but once landed, the wallaby opens its arms,

holding them at a right angle to the body to help it balance.

"The agility of the rock-wallaby in its natural haunts is positively astonishing.

No living creature could be more accurate in its judgement, and no other

animal would dare perform such rapid 'stunts' without bringing the

forelimbs occasionally into action. Leaning trees are easily scaled. When hotly pursued the rockwallaby

will make for the tree at top speed, and without hesitation spring as high as possible up

the trunk, then finally gain a fork or large limb and sit tight,

perched at right angles to the bough, gripping only with the padded soles of the feet, the toe

following the contour of the branch, while the tail hangs down as a balance.

Thus it almost emulates the tree-kangaroo.

(Le Souef, 1926)

There is usually a brief grooming and sunning session at dawn, lasting for less than an hour after

sunrise (Lim et al, 1992). During most of the year, at dusk and into the early evening they

venture out to feed on small herbaceous plants and grasses, often leaving the protection of the

rocks and traveling to the surrounding slopes and flats (Sharp, 1994 & 1998). A period of

inactivity usually occurs in the early afternoon as well as one in the cooler parts of the night.

Males appear to be more constantly active during the day and night, having numerous resting

places throughout their range. The females have more of a tendency to return to their resting

place just before sunrise, with a lull in activity around 6:00 AM (Lim et al, 1987).

In the summer, when temperatures are often above 40 degrees Centigrade, activity during most

of the day is limited, and most are out of the sun by 7:30 AM (Lim et al, 1992). But in winter,

there is a considerable amount of diurnal activity. During the winter, both sexes appear to be

equally active throughout the day and night. They have larger home ranges and activity cores in

the winter, as opposed to summer, and males have larger home ranges than females year-round

(for more details see "Habitat Use" section) (Lim et al, 1987).

Yellow-footed rock wallabies show a high degree of attachment to a particular area of their

habitat. At Middle Gorge they were observed in an area of less than 50 ha 50% of the time and in

an area of less than 250 ha over 90% of the time (Lim et al, 1992).

The yellow-footed rock wallaby is usually found in distinct family groups of six to eight adults.

These smaller family groups are usually comprised of an adult male, several females with their

24


offspring and juvenile males. Group boundaries are probably dictated by the distribution of

shelter sites (Lim et al, 1992).

Larger colonies of up to 120 individuals are often made up of these smaller family groups. The

colony size is determined by availability of suitable shelter site, as well as amount of nearby food

resources (Sharp, 1994 & 1998) and water supply (Lim et al, 1992). The question has been raised

that the appearance that they live in groups may be an illusion due to the limited size of their

specific rocky habitats (Williams, 1999). Although it does congregate in optimum sites, it is

primarily a solitary animal as little interaction between individuals is seen (Adelaide Zoo, 1996).

As in most macropods, the act of nose-to-nose between individuals occurs at the highest

frequency for con-specific interaction. Less common was nosing of other body parts. Kicking or

thumping the ground to produce an audible sound is a common response to disturbance, usually

by a possible predator, as is tail lashing (Coulson, 1989). Prolonged violent encounters for

dominance rarely occur. The most aggressive interactions between individuals involve only

sniffing, hissing, foot stamping, pawing and chasing. Strong adult-adult bonds are formed only

during mating and with occasional allogrooming between a male and female. Most non-breeding

interactions occurred while animals were feeding in groups close to each other (Lim et al, 1992).

The frequency of interaction increases between a mother and her young, and usually involves

allogrooming (Lim et al, 1987). The Adelaide Zoo (1996) also notes that interaction between

individuals in captivity is also highest between mother and young. There has been surrogate

motherhood observed (S. Lapidge, pers. com.).

The rare behavior of oral transfer of fluid from mother to young, perhaps an adaptation to the

habit of the dam leaving at-heel young behind unattended when going out to feed and drink, was

first observed in 1977. A yellow-footed rock wallaby joey, during its second day of being

permanently out of the pouch, was observed licking from its mother's mouth for thirteen minutes

upon her return. When he stopped, a drop of fluid formed on her chin that she quickly licked off.

Water for this particular colony was located several hundred meters away from where the joey

was left. Some Aboriginal hunters felt that rock wallabies stored water in their stomachs as it

was quite common for water to run from a dead rock wallaby's mouth (Lim et al, 1987).

Other maternal acts include pouch grooming, removing urine and feces and at the same time

probably grooming the in-pouch young during the process. The dam will groom the young when

it is out-of-pouch, whether temporarily or permanently. The young can also feed by suckling

from outside the pouch. Less common in macropods, the young often develop their own solitary

play game by hopping rapidly away from the dam and then returning. Most unusually, yellowfooted

young are reported to give a clicking call most often directed at the dam (Coulson, 1989;

Lim, 1987).

During times of stress, such as flight or severe drought, females may tend to throw their older

joeys (13 weeks and older) as a form of self-preservation. Younger joeys (less than 13 weeks)

are more often retained (S. Lapidge, pers. com.). At-heel young are left behind in safe places

while the dam may travel long distances to feed or drink (Coulson, 1989). The life stage

associated with the greatest mortality is just after the young has left the pouch.

25


The rock wallaby's first response to aggression is usually avoidance, a simple form of agonistic

behavior common throughout most macropod species. When frightened or alarmed, they zip

away into a crevice in their rocky habitat and sit quietly until danger has passed. If continued to

be pressed, they will charge right past the presumed danger to escape (Williams, 1999). The

author experienced this energetic charge while in New South Wales, the animal disappearing into

the rocky fissures seconds later. Aggressive chasing may result if their initial avoidance attempt

was unsuccessful. Vocalizations by both dominant and submissive individuals as well as tail

wagging have been noted. They also bite and paw at their opponents when a confrontation

actually ensues. The initial aggressive hop, with the two combatants often leaping toward each

other, may be quite high. A behavior found in the yellow-footed rock wallaby, and only two

others of 33 species studied, was biting at the chest during confrontations. (Coulson, 1989).

Sexual interactions include routine checking, the male nosing the cloaca or the pouch of the

female. Nosing of the cloaca frequently stimulated urination by the female, and the male will

nose this urine. The male will generally paw at the head or shoulder of the female, often grasping

her head and rubbing it against his chest. This sternal rubbing appears to be most frequent and

persistent in the rock wallaby species. If the female is unresponsive, aggressive chasing may

result. A clucking vocalization and lashing of the tail, similar to that seen in a predator alert or

aggressive context, often accompanies male arousal (Coulson, 1989).

For additional information on reproductive behavior see "Reproduction" section. For additional

information on feeding behavior see "Wild Diet" section. For additional information on use of

the habitat see "Habitat Use" section.

26


II. B. HABITAT

DESCRIPTION OF THE HABITAT

Yellow-footed rock wallabies live in colonies on rocky outcrops in semiarid and arid country.

Often the surrounding topography is low, with isolated cliffs and ridges rising steeply where the

rock wallabies are found (Lim et al, 1992). The habitat receives an average of 150-250 mm

annual rainfall, although some of the colonies in the southern Flinders Ranges receive up to 450

mm annually (Copley, 1983). Rainfall is highly unpredictable and often occurs as localized

downpours (Lim et al, 1992). It is the hottest and driest area occupied by nearly all of the rock

wallaby species, and temperatures can reach up to 50 degrees Centigrade in the shade during the

summer (Lim et al, 1987).

The deep caves and fissures of this rocky habitat provide an even temperature and protection

from the often extreme outside temperatures (Ride, 1970). Although surface temperatures soar,

the shelters remain a near constant 29 degrees Centigrade (Domico, 1993).The wallabies use

these outcrops and associated overhangs for shelter from both climate extremes and predators

(Copley, 1983; Sharp, 1998). It is the presence of boulder piles and narrow cracks running deep

into the cliffs that appears to be of critical importance rather than rock overhangs and caves that

are used more often by goats and Euros (Lim et al, 1992).

Most rock wallaby colonies are within 5 km of a water source that lasts through the summer

drought (Lim et al, 1992). Although it is commonly thought that yellow-footed rock wallabies

live only near a permanent water source (even if it is only a soak at the edge of a rock face), there

are colonies that exist where even this scanty water source appears to be unavailable (S. Lapidge,

per. com; Strahan, 1995).

The preferred sites of choice appear to have specific factors of the following components

(Copley, 1983; Lim et al, 1987):

Rock Type: Sandstone and quartzite rock types are greatly preferred. Ninety-three

percent of colonies occur on sandstone outcrops. In the Olary Hills the colonies are on

volcanic rocks (granite-porphyry) (Lim et al, 1992).

Texture and Boulder Size: The presence of boulder piles and deep narrow cracks

appears to be critical for protection from predators and high summer temperatures. This

type of structure is preferred over the more open rock overhangs often utilized by

wallaroos and goats.

Aspect of the Rock Face: South-facing cliffs offer more shelter from direct sunlight,

providing climate conditions that allow for more abundant plant growth. This

orientation also provides cooler summer temperatures.

Presence of Permanent Water: Most extant yellow-footed rock wallaby colonies are

within 5 km of a water source that usually lasts through the dry summer season. The

27


sheltered gorges of their preferred habitat also provides standing water that lasts much

longer than in the surrounding country.

The dominant vegetation is mulga scrub (Kennedy, 1990). There is frequently a greater

abundance and diversity of plants in the rocky areas the rock wallaby chooses to inhabit than is

found in the surrounding arid plains, slopes and ridgetops (Strahan, 1995). This is indicative of a

greater retention of moisture, as the terraces and ledges trap runoff water from the rock surfaces

and the shelter from narrow gullies and rock piles reduce evaporative water loss. Consequently,

the microclimate on the outcrops is milder and the food supply more dependable than in the

surrounding areas (Copley, 1983). A list of the plants eaten by yellow-footed rock wallabies can

be found in the "Wild Diet" section.

Stylized habitat of the yellow-footed rock wallaby (adapted from Lim et al, 1992).

Sheltered valley: Casuarina pauper, Helichrysum ambiguum, Solanum spp., Stipa

variabilis and Calotis cuneifolia

Terrace: larger Acacia spp.

Plateau: Callitris columellaris, Acacia aneura, A. clavicola, Digitaris spp.

Cliff: Capparis mitchellii, Ptilotus spp., Cassinia spp., Abutilon spp., Digitaria brownii

Slope: Alectryon oleifolium, Acacia aneura, Casuarina pauper, Vittadinia spp.

Plain: Atriplex spp., Rhagodia spp., Sclerolaena spp., Maireana spp.

28


The Gap Ranges in New South Wales offer classic rock wallaby habitat. The rocky cliffs and

outcroppings appear to spring from the flat surrounding plains. The distance between the rocky

hills often influence rock wallaby dispersal, as it is often inhospitable habitat, thus forcing the

animals to remain in a colonial social organization. Under usual conditions, the slopes

provide a more varied selection of plant life than the nearby plains.

29


HABITAT USE

A generalized diet, continuous breeding and embryonic diapause (see Reproduction section)

allow yellow-footed rock wallabies to exist in extreme conditions in their arid and semiarid

rocky outcrops (Pope et al, 1996). The presence of rock wallabies can be detected by the high

gloss which their feet give to the rocky floors of the caves in which they live as well as by their

droppings, which are elongated with pointed ends and not round as are other wallaby's pellets

(Ride, 1970).

The colony size can range from just a few animals up to 200 individuals or greater (S. Lapidge,

pers. com.). Colony density can be from 1.0 per square km up to 22.8 and even 29.1 per square

km (Lim et al, 1987). Although most activity is in the late afternoon or evening, rock wallabies

can be seen sunning themselves during daylight hours if the temperature is not too high.

Otherwise, they seek the shelter of the caves and outcroppings (Ride, 1970).

Home range is defined as the area in which an individual spends over 90% of its time. These

usually include a number of rock piles and a water source, although as stated, this presence of a

water source has been disputed with recent findings (S. Lapidge, pers. com.). The center of

activity, or core area, refers to the area in which an individual can be found 50% of the time

during the same period (Lim et al, 1987).

In a study done at Middle Gorge in 1981, the mean home range of males was found to be 168.8

hectares in winter and 210 hectares in summer. Females were found to have mean home ranges

of 164.3 hectares in winter and 134.3 hectares in summer. There was also overlap in home

ranges between individuals of both sexes during all seasons. The mean overlap was 58.13% of

the individual's home range in winter and 58.59% in summer (Lim et al, 1987). These results

were similar to homes ranges of 150-200 hectares for both sexes stated by Maynes in 1989 and

130-210 hectares, depending on the season, found by Steven Lapidge (pers. com.).

Studies done by Andrew Sharp indicate that the Queensland subspecies (Petrogale xanthopus

celeris) have home ranges of 20-40 hectares as compared to the 160-210 hectares home ranges of

the South Australian species. These results suggest that the South Australia habitat is more

marginal, requiring a larger area of land to meet dietary needs (Sharp, 1994).

The 1981 Middle Gorge study showed that activity cores was found to be the same for both

sexes in winter (27.5 for males; 27.59 for females). However, activity cores in the summer varies

greatly between the sexes. Females were found to occupy cores of an average 25.4 hectare, very

little difference from their winter activity. The males, however, greatly increased the size of their

core to an average 41.45 hectares (Lim et al, 1987).

The above observations suggest female dominance over males for choice in selecting resting

sites. This allows females to occupy prime forage and refuge sites, thus curtailing their need to

travel in the hot summer months. This also supports a theory of greater stability of the female

population (Lim et al, 1987). Females were also found to be more effectively able to defend

important refuge areas than males and also appeared to have a higher survival rate (Robinson,

1994).

30


Males moved significantly faster than females, averaging 375 m/hr and females averaging 187

m/hr. They also traveled further per hour in summer than in winter. In winter, the time of day did

not affect the distance traveled. However, in summer, the time of day was a significant factor in

distance traveled (Lim et al, 1987).

Colonies are not evenly distributed throughout their geographic range and are instead separated

by stretches of unsuitable habitat. This strong habitat specificity results in naturally patchy

distribution at a local, as well as on a broader scale (Pope et al, 1996). Although these colonies

are often widely-separated, the genetic similarities throughout their range suggests that

historically there was a reasonable level of gene flow between the colonies due to dispersal of

animals (Lim et al, 1987).

Reasons for dispersals generally fall within three categories: 1) in response to resource depletion,

2) resource conflicts (usually mates) results in dispersal of individuals of lower rank and 3)

strategy to limit the deleterious effects of inbreeding (Sharp, 1997). Effective dispersal between

yellow-footed rock wallaby colonies even as close as 10 km, with apparently suitable habitat

inbetween, is limited due to three types of barriers to gene flow: 1) geographical distance, 2)

ecological distance and 3) behavioral distance, all three probably playing a role (Pope et al,

1996).

Young male rock wallabies, approaching sexual maturity, are the main dispersers. Young

females appear to be more tolerated by their group and thus tend to remain in place (Lim et al,

1992).

A 1991-1994 study of the Queensland subspecies of yellow-footed rock wallaby, Petrogale x.

celeris, indicated that 1) inter-colony dispersal is infrequent (a single dispersing male), 2) a high

degree of movement does occur between groups within colonies and the majority of those

moving were males, 3) the timing of dispersal may be linked to periods of high mortality and/or

social turnover and 4) the theory (by Lim, 1987) that colonies are comprised of distinct groups

plus transients may be correct (Sharp, 1997).

Due to this limited dispersal, colonies of yellow-footed rock wallabies should be regarded as

independent population units for conservation management at this time. However, a high level of

dispersal among social groups within the same colony does continue, with male dispersal rate

(15.8%) being higher than female dispersal (8.3 %) (Pope et al, 1996).

Steven Lapidge (2000, pers. comm.) confirmed that dispersals between colonies have not been

seen in recent times.

31


II. C. WILD DIET

DIET IN THE WILD

The yellow-footed rock wallaby’s diet has been studied more intensively than many other rockwallabies

due to concerns over its threatened status in its disjunct range. Results show it as an

intermediate browser/grazer (Hume, 1999), with grass being a preferred food (Adelaide Zoo,

1996). During grazing, they feed on vegetation between rocks and at the bottom of piles. During

browsing, they use their front paws to grasp bushes and low trees to bring them down to eating

level (Lim et al, 1987).

They are largely opportunistic in their choice of plants and dine on grasses and monocots, forbs

(herbaceous plants other than grasses such as small fleshy shrubs and ferns that come after a

rain), chenopods (both flat and round leaved, including some saltbush and bluebush), browse

(including trees and woody shrubs, and plants with stellate trichomes (the epidermis consists of

tightly locked, multi-armed star-shaped hairs). There is a strong correlation between rainfall and

diet selectivity, with increased rainfall heightening this selectivity (Lapidge, 1997).

As in other wallabies and kangaroos, the large forestomach is adapted for microbial fermentation

of cellulose (Adelaide Zoo, 1996). But, unlike most other kangaroos and wallabies, yellowfooted

rock wallabies must return to their colony sites at dawn, limiting the area over which they

can travel to find food. To compensate for this, they eat a wide variety of herbaceous plants and a

broader range of foods then most other macropod species. They eat a large number of leaves,

believed to be picked up off the ground instead of directly from the trees as these are usually out

of their reach (Sharp, 1994), although they have been known to climb fallen or slanted trees

(Hume, 1999).

In good seasons, forbs (Cyanoglossum australe, Vittadinia triloba, Psoralea patens and Senecio

spp.) make up half their diet, but drops considerably in poorer, drier conditions. In good seasons

they also eat a high percentage of grasses (Themeda australis and Digitaria brownii), and a

smaller percentage of browse (Capparis mitchelli, Callitris columellaris and Acacia spp.)

(Lapidge, 1997).

Under dry conditions, browse forms the majority of the diet (44%), followed by grasses (22%)

and plants with stellate trichomes (15%) (Ptilotus obovatus, Sida petrophila and Abutilon

leucopetalum) (Lapidge, 1997). In periods of drought, browse becomes the largest single

component of their diet (Hume, 1999).

This diet often overlaps directly with the diet of feral goats, the percentage increasing in poor

conditions. During good conditions, the diet of both is dominated by forbs, chenopods and

grasses, but in poor conditions, browse (such as dry leaf litter from Acacia trees) was the major

food source for both herbivores. Diet overlap with feral goats can be as high as 75% in poor

conditions and as low as 41% in good times. The implications of this pronounced dietary overlap

is of major concern for the future survival of the yellow-footed rock wallaby in some areas

(Hume, 1999).

32


In contrast, Euros consume mainly grasses, so their diet overlaps with that of the yellow-footed

rock wallaby most during times of abundant plant matter (Hume, 1999). A study by Dawson and

Ellis in the 1970s found this overlap from as low as 19% to a high of 39%. The same study

indicated that the diet of the rock wallaby can also overlap that of the rabbit by as much as 53%

during poor conditions (Lapidge, 1997).

One of the concerns regarding Adelaide Zoo's reintroduction of yellow-footed rock wallabies to

Aroona Dam in the Flinders Ranges was whether or not the captive born animals involved in the

initial release could adapt their diet from the prepared diet and supplemental grass and browse

offered at the zoo to the plants available at various times in the wild. In preparation for this

adjustment, prior to release all supplemental feeding was ceased to encourage natural foraging

behavior in the large holding enclosure (Barlow, 1997).

As part of his Honours Degree of Bachelor Science at Flinders University of South Australia,

Steven Lapidge completed a dietary study on the reintroduced animals. He found that only one

month following release, the captive born animals had already reduced their grass intake from

63% to 50% and had supplemented this change by increasing their browse intake to 13%

although the relative availability of both groups had remained stable. Two-and-a-half months

after release, they had further reduced their grass intake to 44%, and browse intake had increased

to 15%. An even greater change occurred with the consumption of plants with stellate trichomes,

relatively unavailable at Monarto Zoological Park where the released animals came from, which

had previously made up only 2% of their diet. Within a few months after release, consumption of

these plants had increased ten-fold, and now made up 20% of their diet although relative

availability of this group remained low (Lapidge,1997).

A complete list of plants eaten by yellow-footed rock wallabies in the wild follows.

33


Plants eaten in the wild (1=Lim et al, 1987;1A=Lim et al, 1992; 2=Lapidge, 1997)

Seasonal preference notes from Lim et al, 1992; IS = introduced species:

1. Grasses

Aristida nitidula (1, 1A, 2) summer

Chloris ssp. (1A)

Cymbopogon ambiguus (1, 1A, 2)

summer

Digitaria brownii (1A, 2)

Enneapogon spp. (1, 1A) winter

Paspalidium bascladum (1,1A, 2)

spring / summer

Sporobolus spp. (1A)

Stipa variabilis (1, 1A, 2)

winter / spring / summer

Themeda australis (1, 1A, 2) summer

Triodia irritans (1, 1A, 2)

spring / summer

Tripogon loliiformis (1, 1A) spring

Triraphis mollis (1A)

Vulpia myuros (IS) (1, 1A) winter

2. Forbs – herbs other than grass

Boerhavia spp. (1, 1A) summer

Calandrinia spp. (1, 1A, 2)

spring / summer

Carthamus lanatus (IS) (1, 1A) summer

Cheilanthes spp. (1, 2) winter / spring

Cyanoglossum australe (1A, 2)

Echium plantagineum (IS) (1, 2)

winter / spring

Euphorbia stevenii (2)

Helichrysum ambiguum (1, 1A) winter

Medicago denticulata (IS) (1, 1A, 2)

winter / spring

Nicotiana velutina (1, 1A, 2) summer

Oxalis corniculata (1, 1A) spring

Parietaria debilis (1, 1A) summer

Psoralea patens (1A, 2)

Senecio spp. (1A, 2)

Sisymbrium orientale (IS) (1, 1A)

summer

Sonchus oleraceus (IS) (1, 1A) spring

Vittadinia triloba (1A, 2)

Zygophyllum sp. (1, 1A) early summer

34

3. Chenopods

Atriplex eardleyae (1, 1A) summer

Enchylaena tomentosa (1, 1A, 2)

summer

Maireana radiata (1A, 2)

Rhagodia sp. (1, 1A) summer

Sclerolaena spp. (1A)

4. Browse

Acacia spp (1, 1A)

Alectryon oleifolium (1A)

Callitris columellaris (1, 1A, 2) spring

Capparis mitchelli (1A, 2)

Cassia desolata (2)

Cassinia laevis (1, 1A, 2)

winter / summer / autumn

Casuarina cristata (1A)

Dodonaea spp. (1, 1A) summer

Eremophila freelingii (2)

Eremophila longifolia (1, 1A, 2) all

Goodenia albiflora (1, 1A)

spring / summer

Prostanthera striatiflora (1, 1A) autumn

Teucrium corymbosum (1, 1A) summer

5. Plants with stellate trichomes

Abutilon leucopetalum (1A, 2)

Abutilon otocarpum (1, 1A) summer

Ptilotus obovatus (1, 1A, 2)

summer / autumn

Sida calyxhymenia (1A)

summer / autumn

Solanum petrophilum (1, 1A, 2) all

Solanum sturtianum (1, 1A) summer

Sida petrophila (1, 2)


WATER DEPENDENCY

It was commonly believed that yellow-foot colonies were always found near permanent fresh

water, even if this water was just soaks up the rock faces. This dependency has been recently

questioned (S. Lapidge, pers. comm.). However, reproduction does appear to be dependent on

water, as well as food, availability.

Yellow-footed rock wallabies have been found to travel up to 5 km to reach water in drought

times (Williams, 1999). Their water turnover is 60 ml/kg daily in the summer. During wet

weather it increases to 150 ml/kg daily (Lim et al, 1987). Water turnover in their dry

environment is reduced by seeking shelter during the day in caves where the relative humidity is

considerably higher than outside and the air temperature is 10-15 degrees Centigrade cooler

(Adelaide Zoo, 1996).

During periods of lush growth, enough water may be supplied by their diet, but there is a point

during summer or drought when the diet fails to provide enough water and they begin to rely on

drinking free water. During this time, rock wallabies tend to congregate near the permanent

water source and abandon the rock piles used at other times. Feral goats, if present, also tend to

congregate at water holes during this time, and severe habitat damage can result from these large

concentrations. Shortage of water and food during a drought can have a large effect on rock

wallaby population numbers as indicated by the 50% drop in the New South Wales colonies

during the 1982-83 drought (Lim et al, 1992).

Females carrying pouch young during a drought may lose their larger joey and replace it with the

one waiting in utero (embryonic diapause). This allows her to save the valuable nutrition she

needs to survive that was being tapped by the larger joey. In severe drought, the female will

cease to come into season at all, and the young in utero will fail to develop so no young are born

until conditions improve. Within two weeks of rain the female comes into season or the

development of the diapaused embryo resumes and reproduction continues (Williams, 1999).

This dependency of reproduction on weather conditions was seen in a study of yellow-footed

rock wallabies in the Flinders Ranges. Where animals were experiencing drought conditions with

no supplemental water source available, the females had no pouch young. But, less than 2 km

away where females had access to a water-well, they were carrying young (Williams, 1999).

Once a joey has left the pouch, it gets left unattended in a "safe" spot among the rocks while the

dam goes out to feed. This means that the joey will not accompany its dam to drink. The species

has evolved a system where, in addition to suckling, the young are able to obtain fluids by direct

mouth-to-mouth transfer from its mother (see "Behavior" section for additional information on

this water transfer).

35


II. D. REPRODUCTION

REPRODUCTIVE BIOLOGY

Mean age for first reproduction in females is 541.3 days (Bach, 1998), although they have

reproduced at 15 months, and Adelaide Zoo has had females with joeys in pouch at 12 months

(P. Whitehead, pers. com.). Although there have been fewer data collected on the age of sexual

maturity in males, behavioral observations indicate maturing occurs during the second year.

Testes begin to increase in size at 15 months and full spermatogenic development was seen in

captive animals at 30 months (Bell et al., 1989). Male dominance and competition may likely

dictate when young males are capable of reproduction (Adelaide Zoo, 1996). The studbook data

support these observations. North American captive reproduction appears to be highest in

females between 2–4 years of age, and highest in males between 6–9 years of age. In the wild,

females up to 11 years old have been found to have pouch young (Robinson, 1994).

Macquarie University has successfully cross-bred the yellow-footed rock wallaby with the

Prosepine rock wallaby, Petrogale persephone, obtaining fertile young (Lim et al, 1987). At

Adelaide Zoo, yellow-footed rock wallabies have also been used in a cross-fostering program

with brush-tailed rock wallabies (Petrogale penicillata) in a study to increase the reproductive

rate of the brush-tailed rock wallaby (P. Whitehead, pers. com.).

There is no distinct breeding season, but in the wild reproduction is affected by drought and

increase following periods of effective rainfall. (Lim et al, 1987). Although there is a correlation

between births and rainfall in the wild, in captivity, there does not appear to be a particular

breeding season, regardless of rainfall if correct diet is maintained (Adelaide Zoo, 1996). A

thirteen-year study at Canberra showed significantly more births (44 out of 62) occurring in the

first half of the year. This study also found that females often lose pouch young and even

suppress regular estrous cycles when handled daily for long periods (Poole et al, 1985).

The sex ratio of births by animals breeding for the first time did not vary significantly from 1:1.

However, births from older females, or where consecutive births were recorded, appeared to

favor males as much as 2:1. In a study at Middle Gorge, the sex ratio bias had been lost by the

time the young reached sexual maturity, suggesting either a higher mortality or dispersal of

young males (Lim et al, 1992). Female joeys produced by young females are essentially for

recruitment into the natal or a nearby colony. Possibly in the wild the extra males produced by

older females help sustain a male-exchange system with nearby colonies. This unbalanced sex

ratio in older females or consecutive births has also been observed in the captive colony at the

Adelaide Zoo (Robinson, 1994). The most extreme sex ratio of pouch young for a macropod

found in a captive colony of yellow-footed rock wallaby was during a thirteen-year reproductive

study begun in 1965 on Adelaide Zoo animals transferred to Canberra where 41 males and 21

females were born during the time period (Poole, 1985).

The estrous cycle is 30-32 days (Adelaide Zoo, 1996). Most observations have shown that the

female comes into heat when there is new-born young in the pouch, but not again until the young

has left the pouch (Sharman et al, 1996). Birth of a diapaused embryo takes place at an average

36


of 32 days following removal of pouch young and there is an average of 35 days from removal of

pouch young to estrous without an intervening birth (Hayssen, 1993; Poole, 1985).

The male follows a female as she approaches estrous. Behavioral signs of pending mating

include male tail wagging and clicking, followed by scratching of the female’s tail and finally

grasping the female around the chest (Adelaide Zoo, 1996). Breeding usually involves only the

dominant male and occurs on or near the female's resting places. During copulation, which can

take up to 45 minutes, the male mounts the female from behind, places his forearms between the

female's thighs and presses his head and chest against her back. Most breeding activity is

between resting and feeding periods, often intermixed with foraging (Lim et al, 1987).

Gestation is usually 31-32 days (Adelaide Zoo, 1996), with a range of 29 – 33 days (Bach,

1998). Birth is usually followed by estrous, mating within one to four days and a resulting

lactation-controlled embryonic quiescence (Poole, 1985).

Although females usually give birth to one offspring, two sets of twins out of 36 births were

recorded in P. xanthopus (unknown subspecies) at the London Zoo (Collins, 1973).

During lactation, the milk of P. xanthopus reaches solids concentrations as high as 34%.

(Merchant, 1989).

Pouch emergence occurs between 189 – 227 days of age (Bach, 1998), with an average of 194

days (Adelaide Zoo, 1996).

PARENTAL CARE

In the majority of kangaroo and wallaby species, the “at-heel” stage (the time between first

pouch exit and permanently out of the pouch) is a month or more. During this time the young

animal can learn to negotiate in the world, yet have the safety of the pouch to return to should

problems arise. In the yellow-footed rock wallaby, however, this period of interim pouch life

lasts only 7-10 days. Although they will continue to nurse for another few months, once the

interim pouch life is over they are physically on their own and in a very precarious stage of

development. Females will leave their young in protected areas for long periods of time while

they go out to drink and feed, only returning to nurse the joeys (Lim et al, 1987). This interim

life stage is the point at which rock wallabies become most vulnerable to predation in the wild or

stress-related illness in captivity.

Interactions between dams and joeys are the most noted intra-species behaviors and for more

information see the "Behavior" section.

JOEY DEVELOPMENT

A new-born yellow-footed rock wallaby weighs an average of 508 mg when it exits the birth

canal and makes its way to the pouch (Hayssen, 1993). During one occasion when birth was

actually observed, the newborn had already attached to a teat only 75 minutes later when the dam

was caught up for inspection (Poole et al, 1985).

37


The measurements most commonly used in aging joeys (in association with weight) are

(Williams 1999):

a) Head – nose to the back of the skull

b) Foot – back of the heel to the end of the toe (excluding nail)

c) Tibia – top of the knee to level with bottom of the foot (when held at right angles)

d) Tail – from rump to tip

Some measurement averages of growing joeys are (Williams, 1999):

Age in days 40 60 80 100 120 140 160 180 200

Head (mm) 27 33 40 50 56 60 72 80 85

Foot (mm) 18 28 40 52 68 90 110 125 -

Length of head appears to provide the most reliable criterion for age determination. Body

measurements should not be used for age determination for wallabies over the age of two as they

then become unreliable (Poole et al, 1985).

According to Bach (1998), developmental averages are as follows:

Eyes open 102-127 days

Detachment from teat 119-138 days

Appearance of body hair 121-143 days

Head out of pouch 130 days

Permanent pouch exit 189-227 days

Both sexes are of similar size until pouch exit. At emergence, the young animals are about half

their final size but only about 10% of their final weight. At this point, the males gradually

become larger than the females, eventually developing longer limbs and greater weight (Poole et

al, 1985)..

For detailed developmental data, see the following pages taken from "Birth Date Determination

in Australasian Marsupials" edited by Carol Bach and published by ARAZPA in 1998.

Joeys have been successfully hand-raised from about 135 days, although somewhat younger ones

could probably be successful but have not been documented. Joeys pulled for hand-raising

between 160-200 days have usually been pulled due to public relations reasons (not a

recommended procedure) and not because of a health problem. It is important to watch for

dehydration and water should be available at all times for older animals. Feeding from a bowl

instead of a bottle, even at a very young age, is recommended for reasons of hygiene (Adelaide

Zoo, 1996).

The most common problems associated with hand-rearing are dehydration, diarrhea, trauma,

shock, infections, pneumonia, and intestinal worms (Muranyi, 2000).

An age, growth and feeding chart follows, including sources for bottles, nipples and formula. If

an emergency situation arises and formula is not available, one of the following temporary

formulas can be used:

1) 120 ml pasteurized cow's milk, 0.5 teaspoon glucose, 2 drops ABDE vitamins

2) 10 grams Esbilac, 100 ml water, 0.1 ml ABDE vitamin drops

38


General guidelines for number of feedings a day are (Muranyi, 2000):

unfurred (stage 1.0)

(permanently out of pouch) 2 times daily pellets

Some tips for successful hand-rearing are (Adelaide Zoo, 1996):

• A furless joey cannot regulate its own body temperature so this must be closely

monitored. A surrogate pouch temperature between 30-32 degrees Centigrade must

be maintained for furless joeys. Once furred this can be reduced to 28 degrees

Centigrade.

• The pouch, made from a soft washable material, should be just big enough for the

joey to move around and remain in a natural position.

• Change pouches whenever they get soiled.

• Use correctly shaped and sized nipples to avoid mouth problems.

• Check the milk for correct temperature on inside of wrist. Sterilize all bottles and

teats after each use.

• Feed the joey while it is inside the pouch and position it so that it is sitting up

and not laying back.

• After each feeding, gently stimulate the joey to defecate and urinate, a process

normally done by its mother.

• Massage or gently move about in the pouch after feeding to exercise the joey's

muscles, as the natural movement of the mother's pouch is lacking.

• Use baby oil, hand cream or lanolin should the skin become dry.

• Restrict handling to one person if possible.

• If the stool is loose but the joey is holding it between feedings, it is still adjusting and

this should not be confused with diarrhea.

• Continued diarrhea may require a diaper that is frequently changed to prevent

chaffing.

• Diarrhea is sometimes related to lack of natural digestive organisms. Soaking a

normal fecal pellet from an adult in water, separating the solids, and giving

5 mls of the liquid orally can provide these. This should be done only once.

• Check for dehydration, the biggest danger of continued diarrhea, by pinching the skin

where it is loose. If it does not drop back into position, the joey is dehydrated and

needs attention.

• Once pouch emergence begins, start introducing solid foods such as grass, lucerne

hay and chopped vegetables.

• It is better to offer milk for too long than to wean too early.

39


II. E. RESEARCH PROJECTS

HABITAT RECLAMATION (New South Wales)

A study was undertaken in New South Wales during the 1980s to assess the impact on yellowfooted

rock wallabies from competition for food from feral goats. The results, though not

conclusive, suggested that high feral goat populations could suppress rock-wallaby numbers

during times of drought, as during this period the diet for both species overlap and goats outcompete

the wallabies for food. The National Parks and Wildlife Service (NPWS) initiated goat

mustering and aerial culling and between 1987 and 1995 they removed over 36,000 goats from

Mootwingee National Park and the Coturaundee Nature Reserve. Many of the carcasses where

left to rot, providing an easy source of food for feral foxes. Aerial surveys indicated that the

rock-wallaby population continued to decline over this period. This level of goat control needs to

be maintained and possibly expanded upon (Sharp, 1998).

The NPWS then expanded its program to determine the impact of feral fox predation on the

rock-wallabies. As mentioned, the goat carcasses provided additional food sources for foxes and

may actually have helped increase their numbers. But the decline in the rabbit population due to

the 1980 release of a virulent strain of Myxomatosis may have had a larger impact on the rockwallabies

by leading to prey switching from the now-rarer rabbit to the rock-wallaby. In addition,

the fox fur market crashed, and fewer animals were being shot or poisoned for their pelts (Sharp,

1998).

In 1995, the NPWS began an intensive fox control program of baiting with 1080 (sodium monofluoracetate),

around rock-wallaby colonies in the Coturaundee Range, while leaving the

Mootwingee National Park Gap Ranges colony unbaited as a control site. After the first two

years, aerial surveys done in August 1997 indicated that the rock-wallaby population along the

baited Coturaundee Ranges increased by 400% while the wallaby numbers in the unbaited

Mootwingee Gap Ranges remained the same. Adult wallaby survivorship within the unbaited

area has been high (approximately 90%) even though the population remained stable. This

suggests that predation is indeed mainly on juvenile individuals. Baiting continued in the

Coturaundee Range through June 1999. It was recommended to extend the baiting to include the

Gap colonies after June 1999 (Sharp, 1998).

The project, with support from Environment Australia and Natural Heritage Trust, has been

monitoring not only fox but wedge-tailed eagle diets to assess any increase in wallaby predation

due to the release of the rabbit calici-virus in the study site in September 1996. The removal of

rabbits from the system may result in not only prey switching by predators but also a reduced

carrying capacity of predators. Fox diets are monitored through scat analysis and eagle diets

through examination of prey remains at nesting sites. Yellow-footed rock wallaby remains have

been found in only a minute percentage of fox scats, an indication that wallaby predation by

foxes may actually be quite low. Results of prey examination at eagle nests sites indicate that

rock-wallabies make up only about 3-4% of the wedge-tailed eagle diet. However, with such

limited populations, even low levels of predation may be sufficient to limit rock-wallaby

numbers. (Sharp, 1998).

43


In April of 1998, the author and her husband visited both New South Wales sites to assist with

the NPWS project monthly population estimates. At that time, it was estimated the specific

Coturaundee Range colony visited had a population of 15 animals, and the Mootwingee colony

visited consisted of 35 individuals. The populations of both sites appeared stable, and seven

wallabies were actually spotted during the two days there. The monitoring of the rock wallaby

populations in both the Coturaundee Range and Mootwingee National Park, as well as the fox

control program, continues at the time of publication (P. Christie, pers. comm.).

The New South Wales population remains at an extremely low level. It has been suggested that

additional wild colonies be established as soon as possible. This could be accomplished through

either release of captive-bred animals or translocation of wild individuals. The inclusion of all

rock-wallaby colonies and their foraging areas within the NPWS Estate is important to allow for

direct management. In the Coturaundee Range 60-70% of the colonies lay outside the Service

Estate (Sharp, 1998).

The yellow-footed rock wallaby study site in the Coturaundee Range, NSW, contains areas of

sheer rock face that the rock wallabies easily traverse.

For scale, note author's husband, Russ Menard, below the shrubbery on the left.

(1¼ inches from photo bottom, 2½ inches from photo left)

44


Fecal pellet counts were taken at 100 locations within each of the two NSW study sites. All

pellets found within a meter square (delineated by a PVC measuring device) were recorded,

providing an estimation of rock wallaby population size.

Some of the wallabies in the Gap Ranges study site were radio-collared. Before continuing with

the fecal pellet counts, the location of individual animals was noted.

Limited dispersal to nearby areas has been noted at this site.

45


REINTRODUCTION (South Australia)

The primary goal of reintroduction projects is to form a self-sustaining population in an area the

species formerly inhabited. The best species to be considered for reintroduction are those whose

wild populations have declined but are not yet seriously threatened. A reintroduction project is

considered a success if the population becomes self-sustaining for a period of more than five

years and shows signs of continuing to be (Lapidge, 1997). AdelaideZoo's currently successful

reintroduction of yellow-footed rock wallabies to the Aroona Dam area, Leigh Creek, South

Australia, has resulted in rock wallabies surviving and reproducing in an area of their former

habitat for the first time in 15 years (Barlow, 1997). In fact, Aroona Dam sanctuary is in close

proximity to Sliding rock, the sire where the zoo's found rock wallaby stock is believed to have

originated in 1983 (Hornsby, 1980).

During the 1994 National Rock Wallaby symposium, the Adelaide Zoo received unanimous

support for a trial release of yellow-footed rock wallabies (Lapidge, 1997). Although believed to

be where the first European sightings occurred, the last sightings of yellow-footed rock wallabies

at Aroona Dam had been in 1982. The most important factor addressed before the reintroduction

could happen was ensuring that the release site was secure. This meant that all of the

contributing factors for the decline or demise of the original wild population had been addressed

and either removed or corrected. The land use at the Aroona Dam site was stable, as it had been

dedicated as a Sanctuary in 1995 so its land use would not be subject to change in the future. The

elimination of feral animals (foxes, cats and goats) had also started previously (so far, none of

the few deaths recorded have been attributed to feral animal predation). The rabbit calici-virus

had also passed through Aroona in 1996 eliminating the rabbit population (Barlow, 1997).

Once Aroona Dam was chosen as the reintroduction site in 1995, regular fox baiting with 1080

(sodium mono-fluoracetate) began, as no releases would occur until fox counts were down to

zero. A buffer zone of ten kilometers was created around the sanctuary with the asssitance of

local pastoralists (Barlow, 1999). Since yellow-footed rock wallabies can adjust their dietary

(Lapidge, 1997) and breeding patterns to meet changing environmental conditions, as long as

they were given a predator-free environment, the chances of success were good. In addition, an

electric fence was established northwest of the Sanctuary, neighboring fences were monitored to

keep sheep out, and the feral goat shooting was intensified (Barlow, 1997).

The wallabies selected for release came from Monarto Zoological Park and were selected by

their genetic and physical health, relatively young age, and history of successful reproduction.

Prior to release they were maintained in large naturalistic enclosures, and all processed

supplementary feeding ceased one month before release to encourage natural gut flora and

natural foraging behaviors (Barlow, 1997). The Monarto Zoo group was also desirable as it had

minimal contact with humans and in addition were exposed to some of the threats of natural

predators such as wedge-tailed eagles and could be expected to have learned a more appropriate

response to predation than animals maintained at more traditional zoos (Barlow, 1999).

2.8 animals were selected as a natural sex ratio. All joeys were weaned to increase the chance

that the females would give birth to diapaused embryos after release. The males released had not

sired any of these diapaused embryos. All animals were fitted with 'mortality' radio-collars

('beeping' changes speed when the collar has been stationary for more than six hours) to not only

46


assist with tracking the wallaby's positions, but also to alert researchers of a possible dead animal

so that rapid recovery and necropsy could be performed (Barlow, 1997). These collars were

fitted one month prior to release to allow the animals to adapt (Barlow, 1999).

The release date was schedule for early spring when vegetation and climate would be at optimum

levels to ease adjustment. The reintroduction of 2.7 animals went ahead on September 16, 1996.

One female was temporarily held back due to medical concerns, but was released on October 23.

One male was lost 28 days post-release due to pneumonia (Barlow, 1997).

The released animals were radio-tracked 2-3 times daily for the first 40 days, the optimum time

for death or dispersal to occur. After the wallabies were established in November, directional

radio-tracking was reduced to one week per month, with fixed position monitoring twice daily to

check for alive/deceased beeps (Barlow, 1997). It was later reduced to one week every three

months (Barlow, 1999).

Two additional females were released in September of 1997, almost a year to the day of the

initial release.

The wallabies have created home ranges within the Sanctuary and have developed wild wallaby

behavior of remaining stationary in caves during the day and coming out to forage in late

afternoon and evening (Barlow, 1997). They have learned to eat a wider range of plants

(Lapidge, 1997).

Reintroductions require the support from a wide range of people and organizations. To make a

reintroduction truly successful, perhaps the most important support must come from the local

community. It is hoped that this local community will take the project as their own, giving it

local ownership. The local ownership expressed by the people of Leigh Creek goes beyond any

expectations. The Leigh Creek area school students have been involved with radio-tracking,

compiled issues of "Rock Wallaby News", produced a model of the Sanctuary, and incorporated

the 'Wallaby Hop' at a school concert. The local student-run radio station broadcasts 'Wallaby

Updates'. Wallaby researchers are housed free of charge at 'Wallaby House'. The landowners

surrounding the Sanctuary have continued with the baiting program (Barlow, 1997). Area

residents bait the wallaby traps throughout the year, resulting in higher success rates during the

trapping trips. Major sponsorship was also obtained from local organizations such as Flinders

Power and North American support came from the Los Angeles Zoo. AZA's Marsupial and

Monotreme Taxon Advisory Group's Action Plan also supports this project.

47


The brochure for the Aroona Dam Sanctuary boasts the yellow-footed rock wallaby

reintroduction project as a major attraction although visitors seldom go where the colony lives.

48


In January 1998, Steven Lapidge, Sydney University, began a PhD monitoring study

"Reintroduction Biology of Yellow-footed Rock-wallabies: Effect of environmental variables

and competition with Euros" using the released animals at Aroona Dam and a colony of

Petrogale x. celeris in Queensland. According to Adelaide Zoo's newsletter "Zootimes" that

featured this project in its June 1998 edition, the aims of this study were:

• identify the most successful methods of reintroducing captive-bred rockwallabies

back to the wild;

• determine how individuals and the colony as a whole adjust once released;

and

• examine the effect of environmental variables and sympatric species on the

establishment, ecology and physiology of the yellow-footed rock wallaby.

During this study the wallabies were regularly radio-tracked and monitored for adjustment to the

wild. They were trapped at 3-month intervals using specially designed traps left in position and

baited during the trapping intervals. The monitoring involved recording data on movement,

reproduction, growth, diet, haematology, DNA, water turnover and field metabolic rate.

In April of both 1999 and 2000, the author and her husband joined Steven Lapidge in his

quarterly trapping expeditions to access the status of the reintroduced population at Aroona.

During these trapping trips, the general health of any trapped wallabies was noted, weights taken,

blood drawn, Vitamin E injected, feces collected, radio collars adjusted or added as required and

pouches were checked. New joeys were found during each of these trapping sessions, and there

are now F2 generation wild yellow-footed rock wallabies thriving at Aroona Dam. The last

trapping trip for this study was in January 2001, but the monitoring of the population will most

likely continue through radio-tracking of the already collared individuals.

Aroona Dam is the center of the reintroduction site at Leigh Creek, SA.

49


The traps were baited with kangaroo pellets and a mixture of dry oatmeal and peanut butter.

Water was provided as it might be several hours before the wallaby was removed from the trap.

In addition, the traps were sprayed with diluted anise - an attractant to the wallabies.

The author and her husband hold rock wallabies in burlap bags prior to processing.

50


Steven Lapidge holds a second generation wild born individual from the captive bred

reintroduced animals – an indication of the success of the project.

After being processed the wallaby is taken to a stable location

away from the cliff face and released.

51


Husbandry

&

Care

52


III. A. HUSBANDRY

EXHIBITS & HOLDING

Although generally nocturnal in the wild, captive yellow-footed rock wallabies can be quite

active during the daytime. If provided with adequate vertical exhibit space, they entertain and

educate visitors with their skilled acrobatics and natural beauty. They do need access to roomy

quarters that allow them to maintain considerable distance between themselves and the public, if

desired (Collins, 1973). It is important to remember that their requirements remain the same for a

holding pen or stall as they do for the actual exhibit, although these can be simpler in design

(Muranyi, 2000).

The exhibit requirements are (Adelaide Zoo, 1996):

• Minimum space requirement per animal is 60 meters squared

• The exhibit must contain:

A series of rock piles with crevices and caves with adequate drainage to allow

frequent cleaning. These piles should incorporate different aspects to allow

the animals to take advantage of the sun, or to escape it.

Enough private areas so these essentially solitary animals can bask without

being crowded

A shelter (a large shed or cave) that provides protection from extreme heat

and/or cold and can act as a dry feeding station, preferably situated within the

rock structure for maximum use.

An area that will enable easy capture such as a raceway or lockaway yard.

An area of available browsing and grass for grazing

• Fences must be a minimum of 1.8 meters high with no footholds at any point. Dry

moats have been used successfully. Branches overhanging fences or moats should be

avoided as yellow-footed rock wallabies have been known to climb trees. There

should be no fence protrusions that can cause injury or death.

• Fresh water must be available at all times

Escape-prevention can be augmented by topping existing fences with inward-leaning netting at a

45 degree angle. Injuries can be reduced by covering any square corners with a loosely supported

fan of standard rabbit netting (Muranyi, 2000; Poole et al, 1985). In addition, all fenceposts

should be positioned on the outside of the fencing, as wallabies tend to race along barriers when

alarmed and could sustain injury if impact with a post occurred (Muryani, 2000).

The ideal outside substrate is well-drained natural soil (Muryani, 2000).

Holding areas should be positioned out of the public's eye. This way captures and treatments can

be done without distractions (Muryani, 2000). Bedding material such as straw or wood shavings

should be provided in the holding/shelter areas. Institutions in areas experiencing colder winter

temperatures than the species would experience in the wild (less than 5 degrees Centigrade) will

need to provide heat in addition to bedding material (Adelaide Zoo, 1996).

Since natural daylight hours in their native Australia vary from a low of 11 in the winter to a

high of 15 in the summer, it may be necessary to supply animals with extra ultra-violet light and

53


extra Vitamin A & D to ensure a healthy condition. This is especially true of newly-imported

animals (Gasking, 1965).

Exhibits and holding areas should be cleaned daily, with special care to feeding areas, to avoid

health problems that can result from poor hygiene. Cleaning time is also a good time to check

enclosures for any hazards to the animals such as breaks in the fence or foreign objects. Also

take this time to visually examine all animals.

SOCIAL GROUPING

Males will interfere with each other and often fight when a female is in season, resulting in the

failure to successfully copulate. In the yellow-footed rock wallaby colony at Adelaide Zoo,

breeding results were poor, or non-existent, when there were as many males as females in the

group. During these times there was also high female mortality, possibly due to attacks by males.

Breeding rate is best when there is only one or two males in a colony of up to thirty animals

(Gasking, 1965).

Although rock wallabies will congregate in preferred habitat sites, they are primarily a solitary

animal. Interactions usually involve mother and young or mating pairs. Adult males will fight for

dominance when a female is in estrus. Young males nearing sexual maturity have been known to

be severely stressed and even killed by adult males. This problem can be exaggerated in small

exhibits so all young males should be moved out as soon as possible. When this is not possible,

using visual barriers may help reduce this behavior (Adelaide Zoo, 1996).

A single adult male should be present in a breeding group to ensure the accurate parentage of

young. When changing males, it is recommended to wait several months before introducing the

new male, again in order to identify parentage of any joeys resulting from diapaused embryos.

MIXED SPECIES

Mixed species exhibits have had varying success. At Adelaide Zoo yellow-footed rock wallabies

have been housed with Euros, red kangaroos, bilbies, emu and Australian bustards. No problems

have been encountered, but the exhibit is spacious with two areas of rocky terrain which the rock

wallabies occupy exclusively. Taronga Zoo did not have success housing grey kangaroos with

yellow-footed rock wallabies as a male rock wallaby showed extreme aggression to the grey

kangaroos, but this may have been due to small exhibit size (Adelaide Zoo, 1996).

CAPTIVE DIET

The major vitamin deficiency in macropods is Vitamin E. This is usually related to capture

myopathy (see details in "Common Diseases" section) and it is recommended to give Vitamin E

injections whenever animals are captured or transported, and to provide diet supplements if this

vitamin is low in the diet.

Another diet-related health problem is lumpy jaw (see details in "Common Diseases" section).

Specific pathogenic bacteria invading the oral mucosa cause this and the best prevention is the

54


emphasis of healthy chewing habits to strengthen the gums. The best way to do this is to provide

high-quality browse. Make sure grass hay is a part of the daily diet as it provides good nutrition

and chewing opportunities. Avoid any hay or feed products that have sharp ends to avoid

puncturing the gums. Prevention can also involve feeding solid grains and reducing the

dependency on pellets.

The diet per adult animal to the captive colony at Adelaide Zoo is (Adelaide Zoo, 1996):

Carrot 50 grams

Pumpkin 15 grams

Parsnip 15 grams

Turnip 10 grams

Onion 10 grams

Spinach 1 leaf

Parsley 1 sprig

Mixed grain 70 grams (pellets may be substituted but are not as good for

their teeth)

Lucerne hay free choice

Browse free choice (acacia, melaleuca, ash species)

Vegetable leaves 1-2 large leaves (cabbage, lettuce, etc.)

Fresh grass free choice

Adelaide Zoo also recommends that all vegetables be sliced to manageable sizes and fed in one

morning feed along with any grains or pellets with all other foods being available free-choice

throughout the day. Feed in several feed trays and space far enough apart to avoid the potential

of aggression (Adelaide Zoo, 1996).

Free access to a mineralized salt lick, protected from the weather, is also advised (Muranyi,

2000).

55


III. B. VETERINARY CARE

PARASITES

A wide variety of common internal parasites can be found in rock wallabies. These include 14

genera of Strongyloides, 3 genera of Protozoa and 3 genera of Cestodes. The majority of internal

parasites result in little clinical illness and any health problems attributed to them are usually an

indication of imperfect conditions of captivity (Adelaide Zoo, 1996). Cleanliness is the best

prevention method. Symptoms of internal parasites include weight loss, progressive anorexia and

death if severe (Muranyi, 2000). Many nemotodes can be treated with Ivermectin at 0.2mg/kg

intramuscularly but cestodes and protozoa will not be eliminated by this commonly-used

treatment (J. Martin, pers. com.)

There are two internal parasites, however, that can cause considerable damage. First, the

protozoa Toxoplasmosa gondii is a significant health problem in captivity and possibly in the

wild. The cat is the only definitive host of this parasite, and wallaby contact with infected cat

feces can result in an often-fatal pneumonia and encephalitis. More details are provided in the

following Diseases and Illnesses chart.

Second, and of less significance, the rock wallaby is a potential intermediate host for the

tapeworm Echinococcus granulosus, with the dingo acting as the definitive host in the wild

(Adelaide Zoo, 1996). Another internal parasite possibly descended from cats, dogs, foxes or

sheep is liverfluke (Muranyi, 2000).

A variety of external parasites have been found associated with yellow-footed rock wallabies

including ticks, mites and lice. Mild skin lesions have been associated with the mite Odontocarus

and an increase in numbers of lice (Heterodoxus species) occurs whenever an animal is not

grooming itself. This may explain why during trapping sessions at Aroona Dam in the Flinders

Ranges (see "Reintroduction") some animals were completely free of external parasites while

others were infested. External parasites can be treated using commercially available insecticidal

dusting powders (Adelaide Zoo, 1996).

COMMON DISEASES

Maintaining a healthy environment is the best way to avoid disease problems and immunization

against tetanus is the only vaccination recommended (Adelaide Zoo, 1996). Due to their reliance

on intestinal micro-organisms, care should be given when administering oral antibiotics to use

only those that do not affect this gut flora. Otherwise it is recommended to use injectable

antibiotics (Adelaide Zoo, 1996).

Lumpy jaw is the single most important health problem for macropods in captivity (Muranyi,

2000). Capture myopathy and toxoplasmosis are close seconds in number of incidents and

impact. The following chart covers causes, symptoms, treatment and prevention of many

common diseases and illnesses of rock wallabies.

56


CHEMICAL IMMOBILIZATIONS

Just prior to injection, Xylazine 20 mg/ml is mixed with an equal volume of Ketamine 100

mg.ml and given intramuscularly at the rate of 0.1 – 0.2 ml/kg. Anesthesia can be prolonged by

Isoflurane administered by open mask or closed system. Fully conscious animals can be masked

down with Isoflurane if physical restraint is adequate. This method is good for short procedures

where the animal can be released back into the enclosure in a timely manner. A combination of

Tiletamine and Zolazepam can be used at the rate of 4 mg/kg. The only advantage this drug

appears to have over the Xylazine/Ketamine mixture is the smaller volume, making it ideal for

darting (Adelaide Zoo, 1996).

To sedate very nervous animals for transport or lengthy handing, 1 ml of Valium in each hind leg

of an 8 kg animal can provide quiet for up to four hours (Muranyi, 2000).

Never release an animal back into its enclosure or holding until it has completely regained

composure after an immobilization. Even without total body control and environmental

awareness, their flight response is significantly strong enough to result in injury or death.

IDENTIFICATION

Animals should be identified in a way that staff can correctly identify each individual.

Transponders provide accurate identification when the animal is in hand, but do not help when

trying to ID an animal in a mob. They are also very expensive and vary in readability, as not all

chips can be read by all readers (Adelaide Zoo, 1996, Muranyi, 2000).

Punched ear holes are not recommended as they mutilate the animal and can become hard to

distinguish from natural wounds and scarring.

Ear tags can be metal or plastic. Colored ear tags can be used, but many find them unsightly if

large enough to be used to provide identification at a distance. Small numbered ear tags are good

for in-hand identification. Ear tags are inexpensive, but with any tag, identification is lost should

the tag be torn from the ear, and the remaining hole from the lost tag can be confused with an ear

hole that has been punched. The tag is placed on the inside or anterior edge of the ear, just above

the fold (Adelaide Zoo, 1996, Muranyi, 2000).

Tattooing, usually in the ear, is also good for in-hand identification, but does not work well for

long distance identifying.

HANDLING

Rock wallabies become very stressed and can injure themselves in the panic of flight during a

capture attempt. To avoid possible harm, it is best to accustom the animals to a daily routine

where they are fed in the same area (care must be taken to keep this area clean) and/or moved

past the same point on a regular basis. This enables them to be caught unaware in a netting

system or, they can be darted as they feed. It is also encouraged to maintain a routine of regular

59


keeper entry to check on the animals, accustoming them to the presence of humans (Adelaide

Zoo, 1996).

Although the species is not as susceptible to capture myopathy when handled briefly (Steven

Lapidge, pers. comm.), continual handling is not recommended, and it has not been shown that

they can become accustomed to it. Female will often lose their pouch young, and even suppress

regular estrous if handled daily for long periods (Poole et al, 1985).

To reduce the deleterious effects on muscle during capture and transportation, an intramuscular

injection of 30-40 IU (International Units) Vitamin E and selenium is recommended. Dosage is

0.2 ml/10 kg (Adelaide Zoo, 1996).

Catching rock wallabies when the ambient temperature is more than 30 degrees Centigrade is not

advised (Adelaide Zoo, 1996).

Adelaide Zoo’s Husbandry Manual (1996) describes various methods of capture:

1.Catching within confined areas: grab the base of the tail as the animal

moves past.

2. Catching within exhibits (requires a number of people to act as drivers and

catchers):

a. Using a long-handled pole net: the best results are achieved by running the

wallaby along a smooth fence line or wall and intercepting with the net. If a

shelter is used, they can also be netted as they exit.

b. Darting with chemical immobilizing drugs: a blow pipe is the

preferred method for this, and it is not recommended for females with

pouch young, as the joey may be inadvertantly hit through the pouch

wall.

3. Catching within an open range enclosure: a large drop net placed in a concealed

location at a 60-90 angle to the fence, or across a raceway. The net can

either be dropped onto the animal as it moves through the area or,

alternatively, it is laid on the ground and lifted as the wallaby moves past.

Darting with an immobilizing drug is usually not recommended and must be done with extreme

caution. The rock wallaby's response to flee and find shelter high in the rocks can lead to a

dangerous and possibly fatal situation once the drug starts to take affect (Muranyi, 2000).

Catching in baited traps can be very successful, but the animals cannot be allowed to remain

inside the traps for any prolonged period, especially when temperatures exceed 30 degree

Centigrade or the sun is on the trap during heat of the day. Rock-wallabies are prone to injury

because of their propensity, even when undisturbed, to hurl themselves repeatedly against

unyielding wire traps (Lim et al, 1992). However, the wild animals trapped in wire traps at

Aroona Dam usually quieted soon after being trapped and most often remained so until

disturbed. If the trap remains in a secured open position and baited routinely, the wallaby will

usually return to them even after being caught. This is seen quite often during trapping sessions

at the reintroduced colony at Aroona Dam as the same wallaby may be trapped days in a row,

60


indicating that there is no prolonged fear of the traps. The key is to leave them baited and open

when not in use.

When removing an animal from the trap, open the door just enough to reach a hand in and grab

the tail as close to the body as possible. If the trap can be moved, place it in an upright position

with the trap door on top before reaching in. Once the tail hold is secure, slowly pull the animal

out. Never remove from a trap in an unprotected location, as the wallaby will surely struggle and

escape if possible.

Hold the wallaby away from the body as they will kick, scratch and bite. Since they try to twist

free, allowing the tail to turn within the grasp avoids the risk of serious muscle and ligament

strain on the animal’s tail and back. Do not grasp any body part other than the base of the tail as

broken bones or other injury can result if an arm or leg is tightly restrained (Adelaide Zoo,

1996).

When a higher degree of control is needed, hold at the base of the tail and bring the other hand

up between the forelegs and grab the base of the jaw, forcing the wallaby’s back to rest against

the handler's chest. When done properly, there is no risk of being bitten, but it does take practice

(Adelaide Zoo, 1996).

Pouch checking will require at least two people and preferably three. One person restrains the

animal against their body in the above fashion, and the other holds the hind legs down to avoid

kicking. If available, a third person will check the pouch (Adelaide Zoo, 1996).

Placing the animal in a bag (hessian, burlap or calico) allows a greater amount of handling and

manipulation. Most animals begin to relax immediately when placed inside the bag. Pouch

checking can be done by exposing the pouch only. The animal can also be weighed, ear-tagged

and micro-chipped all while in the bag. Wallabies can also be contained for up to half an hour in

the bag if it is secured at the top and hung in such a way that it is not touching walls or a fence

and the animal is not seriously stressed (Adelaide Zoo, 1996).

The bag should be made out of thick material, such as canvas, so little light is coming through as

wallabies settle faster in darkness. There should be no loose threads or holes in the bag where

they could get tangled, and all seams should be reinforced (a flat felt seam is recommended). A

variety of sizes may be necessary to accommodate animals of different ages. It should have a

wide enough mouth so the animal can easily be placed in the bag, and enough room for it to

move comfortably about, but not so large as to hamper manipulation of the wallaby once inside

(Muranyi, 2000).

Successful use of the bag requires two people, one to hold the animal by the base of the tail, the

other to hold the bag open. The bag should be lowered and lifted up over the wallaby rather than

the wallaby being lifted up and into the bag. Do not try to put a struggling animal in the bag,

instead hold securely by the base of the tail until it has calmed down (Muranyi, 2000).

61


For weighing, the bag is the best technique, as the wallaby will most likely relax inside it, and it

can be hung on a hanging scale. Always remember to secure the opening well and subtract the

weight of the bag for an accurate animal weight.

Do not release an animal that is still exhibiting any effects of an immobilizing drug, wait until it

is fully recovered. When releasing from a handhold, bag or crate, make sure it is directed away

from any sudden drops or obstacles, as it will take a few moments for the wallaby to reorient

itself. Some females have a tendency to throw pouch young shortly after release and it is

recommended to temporarily secure the pouch opening with tape or a few stitches with a quickly

dissolving suture material.

There are many problems associated with wallaby capture and restraint such as capture

myopathy, shock, hypothermia, trauma and respiratory or cardiac failure (Muranyi, 2000). See

the previous chart on Diseases and Illnesses for details. A well-planned capture and quick release

can help avoid these often-fatal results.

TRANSPORTING

As with all animals, especially those sensitive to stress and likely to react adversely, transporting

should be done extremely carefully. Usually only health or breeding related moves are

recommended.

There are some general rules to follow when transporting rock wallabies:

1. Do not transport more than one wallaby per transport box or division.

2. Do not transport females with advanced pouch young. Most airlines will not accept a

female with any known pouch young. If transport is unavoidable, sealing the pouch

with masking tape or stitching it shut temporarily may need to be considered to avoid

young exiting the pouch and being neglected or injured.

3. For most transports, a medium-sized kennel (72 cm X 43 cm X 53 cm high) is

appropriate.

4. Provide side ventilation and padding on the roof of the transport crate.

5. Never use a wire crate, solid sides are best.

6. Calculate the amount of food and water necessary according to the amount of time the

animal will be in transport.

7. Provide thick bedding in the form of a non-slip substrate on the crate floor.

8. Cover any ventilation areas with burlap to allow the air to circulate but restrict visual

contact.

9. Choose the most direct route possible and avoid delays at all costs.

10. Label the crate with species, sex and source and target addresses and phone numbers.

Add an obvious note to keep quiet, out of drafts and direct sunlight and not to remove

from the crate unless considered essential by a veterinarian or keeper.

11. Do not transport during temperature extremes.

12. Provide food and water containers with no sharp edges that are secured to the crate.

13. If any questions, follow IATA regulations (diagram included).

62


Once the wallaby has reached its destination, place the transport container in the holding area

and remove the door slowly or secure it open. Exit the enclosure and allow the wallaby to exit on

its own when is ready. Remove the crate after the animal has settled in and calmed down, which

may take up to 1–2 days (Muranyi, 2000).

63


From Live Animal Regulations, 2001

64


From Live Animal Regulations, 2001

65


Bibliography

&

Sources

66


IV. A. BIBLIOGRAPHY

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Evans DD, editor. The management of Australian mammals in captivity, proceedings of the

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IV. B. INTERNET SITES REFERENCED

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WWW


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IV. C. SOURCES

73


ACKNOWLEDGEMENTS

There are many people I would like to thank for their support and assistance in the completion

and publishing of this husbandry manual and associated studbook.

Andy Sharp, at the time working with the New South Wales National Parks and Wildlife

Service, first got me hooked on the species by allowing my husband, Russ Menard, and me to

join an overnight fecal pellet count in the Gap and Coturaundee Ranges north of Broken Hill in

1998. Andy then put me in touch with Suzy Barlow, now at the Western Plains Zoo in Dubbo,

NSW, but who was then at the Adelaide Zoo and the Australian studbook keeper for the species.

Her assistance with my endless data questions was most appreciated. In addition, Suzy put me in

touch with Steven Lapidge, University of Sydney Ph.D. candidate. Steve cemented my devotion

to the yellow-footed rock wallaby when Russ and I joined him in 1999 and 2000 for his trapping

sessions of the Adelaide Zoo reintroduction project at Aroona Dam in the Flinders Ranges.

The staff of Roger Williams Park Zoo, as always, was very supportive. Amos Morris, General

Curator, understood when a studbook issue impacted my schedule. Pat Fredericks, Librarian,

was a great assistance in not only proofing reading but in collating the original document.

Director of Veterinary Services Janet Martin provided feedback and direction on all of the

confusing veterinary issues. Much support was provided by Director of Research Lisa Dabek,

Chair of the AZA Marsupial and Monotreme TAG, as well as a shared love for all things

pouched.

My husband, Russ Menard, who took the studbook cover photograph, understood when I had to

work at home and also assisted with proofing the text. He helps keep my love of fieldwork in

Australia alive with our shared enjoyment of it.

74

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