Byron Flora and Fauna Study 1999 - Byron Shire Council

A GREENPRINT FOR A SUSTAINABLE FUTURE
Koala Phascolarctos cinereus
Regional distribution and abundance. The Koala is widely but patchily distributed throughout northeastern NSW (ANSWW database).
Some populations are sparse whereas others occur at relatively high densities and the region is recognised as a national stronghold
for the species (Scotts 1996). Although densities of up to ten individuals per ha have been reported elsewhere in southeastern
Australia, (Lee and Martin 1988), densities in the region seldom exceed one per ha (ie. Milledge 1988).
There are concentrations of records from fertile sections of the coastal plain in the Tweed, Coffs Harbour, Port Macquarie, Bulahdelah
and Port Stephens areas, and records also show that productive forests along the escarpment such as in the Nightcap and Richmond
Ranges, the Chaelundi area and Dorrigo and Bulga Plateaus support substantial populations (ANSWW database).
General ecology (habitat, shelter, diet, territory, breeding, movements). The Koala occurs mainly in dry and moist sclerophyll forests
but is also found in woodlands and wet sclerophyll forests and occasionally in rainforests. Stands on higher nutrient soils are generally
selected and steeply sloping sites are avoided (Gilmore and Parnaby 1994).
A large range of eucalypt species are used for feeding in the region but the most important species comprise the Red Gums (Eucalyptus
parramattensis, E. seeana, E. tereticornis), Grey Gums (E. biturbinata, E. canaliculata, E. propinqua), Mahoganies (E. resinifera, E. robusta),
Scribbly Gum E. signata, Flooded Gum and Tallowwood (S. Phillips pers. comm., D. Milledge unpubl. data). However, non-eucalypt
species such as Forest Oak and Paperbark are sometimes extensively used. Although Koalas feed on young trees, there is evidence that
they prefer mature trees for feeding and shelter (Hindell and Lee 1987) and particular individual trees within the home range are
usually favoured (Lee and Martin 1988).
Territories are not formed, but individual adult males and females maintain stable home ranges clustered in core breeding groups,
which are separate from similar groups (S. Phillips pers. comm.). Home ranges may be discrete or overlap marginally within these
groups depending on habitat quality. Frequently used trees or ‘interaction trees’ occur around their peripheries, especially near the
centres of breeding groups. Home range size varies from 2-3 up to 15 ha and reflects the density of large food trees (Mitchell 1990).
Most of the day is spent sleeping in the fork of an understorey or sub-canopy tree, although individuals also rest in the upper canopies
of densely foliaged trees or on large horizontal branches beneath the canopies of mature trees.
Breeding female home ranges are arranged in a mosaic with male home ranges but are characteristically centred about the home range
of a dominant male (S. Phillips pers. comm.). Females usually raise one young per year.
Most breeding adults appear to be sedentary within their home ranges, but post-breeding dispersal of sub-adults takes place away
from core groups and individuals may wander freely at this time (S. Phillips pers. comm.).
Conservation status and threatening processes. The Koala is listed on Schedule 2 of the TSC Act, 1995 as Vulnerable. The original
reasons for its listing as an endangered species were ‘population and distribution severely reduced; poor recovery potential; threatening
processes severe; ecological specialist’ (NSW Scientific Committee).
Threats to the Koala include loss and fragmentation of habitat from clearing for agriculture and urbanisation, and losses of mature
trees due to intensive forest management. Disruption to social structure, particularly the loss of dominant males from core breeding
areas, and losses of interaction trees also pose serious threats to the maintenance of core breeding groups (S. Phillips pers. comm.).
Other threats include predation by feral and domestic Dogs and Dingos Canis lupus dingo and disease resulting from stresses associated
with environmental degradation.
Local distribution and abundance. The Koala is widely distributed in the northern section of Byron Shire with strongholds in the
Marshalls Ridges and lower Wilsons Creek-Goonengerry-Upper Coopers Creek areas. In selected locations in these areas densities
appear to approach one individual per 1-2 ha.
Significant populations also occur in public lands in the hinterland including Whian Whian, Goonengerry and Nullum State Forests
and Inner Pocket Nature Reserve. Smaller populations in the Federal and Myocum areas connect those in the hinterland with
additional small populations on the coast in the lower Brunswick River and Tyagarah areas.
The Koala is absent from most of the southern section of the Shire except for the Byron Bay-Broken Head area where it was once
present (ANSWW database) but was assumed to have become locally extinct over the past two decades. However, a number of recent
records in this area suggest recolonisation is occurring, perhaps from individuals dispersing from the Alstonville Plateau.
Local ecology and conservation significance of the study area. The most important habitats for the Koala in Byron Shire appear to be
the moist forests of the hinterland, where Tallowwood and Flooded Gum are dominant or sub-dominant in the canopy, and moist
floodplain and coastal forests where Forest Red Gum, Swamp Mahogany and Red Mahogany are prominent. Drier forests in both
areas containing a high proportion of Small-fruited Grey Gum are also important for foraging.
The populations in the Marshalls Ridges and lower Wilsons Creek-Upper Coopers Creek-Goonengerry areas are likely to be crucial
for the long term health of the Koala on the Shire’s coast and hinterland. The former area supplies colonists for other coastal areas to
the south and north and maintains gene flow between the coast and hinterland via Marshalls Ridges and the Koonyum Range. The
latter area is probably important in supplementing populations in Whian Whian, Goonengerry and Nullum State Forests and also in
maintaining another link to the coast via the Myocum area. However, both these core areas which are centred on private lands, are
under pressure from factors resulting from increasing levels of human occupation. These include habitat clearing, habitat fragmentation,
habitat isolation, increasing numbers of dogs and higher risk of collision with motor vehicles.
Only a small portion of one of the core areas, Marshalls Ridges, is protected by habitat reservation within the Billinudgel Nature
Reserve. Larger reserved areas of habitat in Mt Jerusalem National Park and Inner Pocket Nature Reserve and habitat in other public
land areas such as Whian Whian, Goonengerry and Nullum State Forest, do not appear capable of supporting Koalas at the densities
at which they occur on the private lands. Consequently, planning strategies aimed at protecting Koalas in the latter areas are likely to be
the key to successful conservation of the species in the Shire.
The forests of Byron Shire may become more significant as a regional refuge for the Koala as the density of human settlement increases
to the north and south in Tweed, Ballina and Lismore Shires.
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