WEST KIMBERLEY PLACE REPORT - Department of Sustainability ...

ainforests, including the golden bandicoot (Isoodon auratus) and the golden-backed
tree rat (Mesembriomys macrurus), occupy the patches only seasonally or in response
to external threats such as bushfires. Similarly Kendrick and Rolfe (1991) observed
that none of the 49 reptiles or 13 frogs recorded in Kimberley vine thicket patches
were entirely restricted to these communities. While this behaviour is similar to what
has been observed in Kakadu (Braithwaite et al. 1985), it contrasts with Queensland
where 43 reptiles and 31 frogs have been found to be entirely obligate to (or largely
dependent) wet, high altitude rainforests (Covacevich and McDonald 1993). In the
Kimberley, it was also considered that species present in individual patches are
determined by other biogeographic processes operating outside the rainforest patches,
such as close proximity of grasslands and wetlands for the presence of the frogs
Litoria bicolor and L. inermis. Rainforest thickets, with fewer grasses, offer greater
protection from seasonal fires. Patches are therefore likely to provide local refugia
from which herpetofauna can recolonise burnt savanna communities. Vine thickets
inland of Townsville have been shown to play similar refugial roles (Kahn and Lawrie
1987).
Vine thickets seem to be playing an increasingly important role as refugia for
vertebrates from human-induced environmental changes. As introduced livestock alter
savanna ecosystems and fire frequency increases, vine thickets may be critical to the
long term survival of many vertebrate species. It should be noted that vine thickets
themselves are not immune from these new threats, though patches in rugged terrain
have greater protection (Kendrick and Rolfe 1991). This refugial role is not limited to
the Kimberley, rainforest patches across northern Australia are likely to be just as
important.
The 141 bird species found in the Kimberley's vine thickets occur in equivalent
Northern Territory environments, and no Kimberley endemics have been recorded to
date. The richest Kimberley rainforest bird fauna is associated with moisture
availability and floristic richness, with the highest species numbers being found in the
best developed patches of the northwest coast (Johnstone and Burbidge 1991).
Vine thickets do however seem to play an important seasonal refugial role (Morton et
al. 1995), supporting a range of flighted vertebrates that would not otherwise be able
to survive in the Kimberley without these patches at critical times. Birds such as the
rainbow pitta (Pitta iris) and orange-footed scrub fowl (Megapodius reinwardt) have
been found to be largely confined to vine thickets in the Kimberley. Flying foxes and
frugivorous birds such as the Torresian imperial pigeon (Ducula spilorrhoa) (Russell-
Smith et al. 1992), rose-crowned fruit-dove (Ptilinopus regina) and the great
bowerbird (Chlamydera nuchalis) (Black et al. 2010) frequent these thickets to escape
from the nearby seasonably inhospitable tropical savanna and to access fruiting cycles
closely tied to wet season rainfalls (Bach 2002; Price 2004 and Price 2006). Also
seeking seasonal refuge, the common koel (Eudynamys scolopaceus), visits the
Kimberley vine thickets from neighbouring Southeast Asia (Johnstone & Burbidge
1991). The Northern Territory in comparison has a larger area of high rainfall country
and a greater diversity of closed forest and wetland habitats (Kenneally et al. 1991).
Johnstone and Burbidge (1991) speculated that this is why species such as the rufous
owl (Ninox rufa) are confined to rainforests in the Kimberley but are found in a wider
range of habitats in the Northern Territory.
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