Vol. 15 - Deutsches Primatenzentrum

Page 52 Lemur News Vol. 15, 2010
to receive signals when distant from the source (Schilling,
1979;Irwin et al.,2004).Olfactory signals may transmit information
pertaining to environmental familiarisation (Schilling,
1979), reproductive behaviour and condition (Epple, 1986),
territorial demarcation (Mertl-Milhollen,1979),and inter- or
intra-group spacing (Schilling, 1979; Epple, 1986).
Previous literature has discussed latrines by varying in location
(arboreal, terrestrial, or subterranean), and being further
analysed by volume of faeces and spatial distribution
(Schilling, 1980; Boonstra et al., 1996; Irwin et al., 2004; Pouvelle
et al., 2009). This behaviour appears to be well studied
within other mammals but for primates, especially strepsirhines,
latrine use is only sparsely mentioned within much
broader scope research (Irwin et al.,2004).In this report we
present our observations of this peculiar behaviour exhibited
by the southern gentle lemur, Hapalemur meridionalis,a
threatened primate that occurs in southeast Madagascar.We
will use our observations to review the hypotheses offered
thus far to explain latrine use,i.e.advertisement of sexual cycle,predation
avoidance,intra- group and inter-group spacing
in the context of the fragmented littoral forest.
Methods
This research was conducted from May to July 2008, on the
southern gentle lemur within the Mandena littoral forest
(24°95’S 46°99’E), a coastal forest in southeast Madagascar.
The littoral forest is among the most endangered ecosystems
in Madagascar (Bollen and Donati, 2006) and Mandena
is a protected conservation zone encompassing 230 hectares
of fragmented and partially degraded littoral forest
interspersed with marsh and swamp. Three groups of H.
meridionalis (mean = 5.7 ind/group) were habituated and
followed daily from dawn to dusk with 62 hours of observation
recorded (Eppley and Donati, in press). These lemurs
are of particular interest, as they do not subsist exclusively
on bamboo like the majority of their congeners. Rather, the
southern gentle lemur exhibits a dietary predilection for
terrestrial (turf) grasses while displaying a unique grazing
behaviour (Eppley and Donati, in press). Although the main
research being conducted focused on the feeding ecology of
these animals, opportunistic observations of latrine behaviour
were collected ad libitum. In addition to habitat characteristics
and GPS waypoints taken at the feeding and resting
sites of three groups, latrine locations were also recorded.
Spatial analyses were carried out with ArcMap version 9.3,
with the outermost feeding and resting site waypoints for
each group being used to create the minimum polygon for
their respective ranging areas.
Results
On three separate occasions an entire group of foraging H.
meridionalis were witnessed descending to the ground and
defecating in succession either near or under a high-rooted
tree of different species.Latrine bouts were recorded ad libitum
on a single occasion for Group B (four individuals) and
twice for Group C (seven individuals). Observations took
place within the forest fragment, and were never witnessed
in open canopy areas. The three occurrences of this terrestrial
latrine behaviour were observed shortly after individuals
had awoken from a midday resting bout (between 11:00
and 14:00) at distances approx. 20 m from the resting site.
The three locations where the latrine behaviour was exhibited
are shown in Figure 1.Little overlap between the ranging
areas of the three groups was observed with 0.92 ha (7.74 %)
calculated to exist between groups A and B,0.18 ha (1.68 %)
between groups A and C, and 0.06 ha (0.73 %) between
groups B and C. After an individual had defecated, they
ascended three to four meters and continued feeding.Subsequently,
the group followed an order of sequential defecation,
where by one conspecific would defecate and the next
would rapidly follow.The individuals remaining at an elevated
height always appeared vigilant, scanning the surrounding
area and sometimes continuing to forage, while the conspecific
was on the ground. Upon inspection of two of the
defecation sites, accumulations of hardened faecal matter
were identified. Dissimilarly, the third site consisted of only
fresh faeces with no sign of old faecal matter.
Fig. 1: Ranging areas of the three observed H. meridionalis
groups within the northeast corner of the Mandena littoral
forest. The three latrine sites were observed within the territorial
boundary buffer zones of Groups A & C and B & C.
Discussion
Among primates,latrine behaviour has been recorded (Table
1) in Alouatta seniculus (Gilbert, 1997; Feeley, 2005; Neves et
al., 2009; Pouvelle et al., 2009), Ateles geoffroyi (Notman et al.,
2009), as well as the strepsirhines: Cheirogaleus major, C.
medius, Lepilemur leucopus (Charles-Dominique and Hladik,
1971; Russell, 1977), L. microdon, L. ruficaudatus, Hapalemur
aureus, H. griseus, Prolemur simus, and Lemur catta (Irwin et al.,
2004). With the exception of Neotropical primates, however,minimal
research has been conducted to understand its
function within primates and latrine utilisation is often a matter
of debate. In Ranomafana National Park, for example, H.
griseus have been observed to occasionally use the same
resting/sleeping sites and since they often defecate very soon
after they wake up (Tan,pers.comm.),an accumulation of faecal
material under these trees may appear inadvertently
latrine-like (Notman et al., 2009; Pouvelle et al., 2009). Thus,
latrine use by H.griseus may be anecdotal within this population.
Irwin et al. (2004) presented four non-mutually exclusive
hypotheses for the possible adaptive function of primate
latrines:1) advertisement of sexual cycle,2) predation avoidance,
3) intra-group spacing, 4) and inter-group spacing.
The conveyance of scent-marks is well known to advertise
sexual activity and receptivity (Asa, 2008). If this holds true
for H. meridionalis, latrines should be used more frequently
during the breeding seasons. It has been reported that H.
griseus mate between June and July, experiencing a gestation
length of approximately 137 days (Tan, 2006). Though our
research potentially overlapped with the mating season, we
made no observations of mating during the study period.