Biology Reference
In-Depth Information
To r
Nubbin
Koppie
Bornhardt
Figure 5.9:
Changes in total reptile abundance among four structurally different types of granite inselbergs in
the South West Slopes of New South Wales.
Granite inselberg landform
Inselbergs vary in the amount and arrangement of boulder formations and surface
rock. The most structurally complex landforms such as castle koppies are the kinds
of outcrops that can provide habitat for large populations of rock-dwelling species
of reptiles (Figure 5.9). Outcrops with large boulders and many crevices support
more and larger families of the Crevice Skink (see Box 5.2).
Box 5.2.
The Crevice Skink - a social rock-dweller
The Crevice Skink is a medium-sized lizard that produces from two to six live young
during January and February. It feeds on insects and plant material and shelters
within rock crevices, behind bark, and within the cracks of tree stumps and fallen
timber. It is one of the most common species of lizards on granite outcrops on farms,
even on granite outcrops completely devoid of native vegetation. One reason they
are so common is their partly herbivorous diet and the fact that they excrete small
scat piles on rock ledges which attract a range of insects which the lizards then eat.
The Crevice Skink forms small family groups on rocky outcrops that usually consist
of a breeding pair and several age cohorts of their offspring. On any given rock out-
crop, there may be several different family groups. Family groups spend most of their
time basking on rock faces or sheltering within narrow crevices. When disturbed, they
will retreat within a crevice but will often reappear to investigate the intruder. They
are territorial and will aggressively defend their homes from other lizards, including
non-family members of their own kind. Large extended family groups and a greater
number of families occupy the most structurally complex outcrops and the highest
boulders with lots of crevices. Lizards found near the edge of the outcrop are often
sub-adults and are solitary.
