WEST KIMBERLEY PLACE REPORT - Department of Sustainability ...

mesic communities are often found adjacent to one another in the Kimberley and the
Northern Territory and resident and visiting fauna often use both communities as part
of their life cycles.
There is a significant anomaly in that the floristically richer and taller mangroves of
northeast Queensland have fewer mangal-dependent species of birds than the
floristically poorer and more stunted mangroves of northwest Australia (Schodde et
al. 1982). Kimberley mangrove communities provide vital feeding habitat and shelter
for birds such as the common sandpiper (Actitis hypoleucos) and the whimbrel
(Numenius phaeopus), particularly important in the harsh dry seasons. Furthermore, a
higher proportion of birds that are obligate (confined to) to these communities are
found in the northwest (12 species) than in the northeast (8 species), north of 19°S. A
particularly rich fauna has been observed in the Rhizophora mangrove forests north of
Derby, fed by the freshwaters of the Fitzroy River (Johnstone, R., pers. comm., June
2010). In eastern Australia these birds are found more widely, beyond mangroves into
adjacent rain and gallery forests (Schodde et al. 1982). Birds that have adapted to
these two forms of ecological behaviour are indicative of the refugial importance of
the mangroves juxtaposed against the drier, more exposed savanna communities that
dominate the Kimberley and parts of the Northern Territory. It is speculated that the
mangroves play a seasonal refugial role (Morton et al. 1995) to mangal dependent
birds that use mangroves as a reliable, season proof source of food. This can be
distinguished from the mangal obligate bird species that seem to have developed a
long term residential dependence on the Kimberley mangroves; in other words these
mangroves play an evolutionary refugial role (Morton et al. 1995).
The ecological refugial role (Morton et al. 1995) played by mangroves is also
pronounced for bats species such as Pipistrellus westralis, Mormopterus loriae and
Nyctophilus arnhemensis. These species are endemic to mangroves in the Kimberley
and parts of the Northern Territory; their closest affinities being species that favour
more widespread rainforest communities in north-eastern Australia and New Guinea
(Friend et al. 1991; McKenzie et al. 1991).
While mangrove and vine thicket environments perform these roles elsewhere in
northern Australia, the importance of mangroves in the Kimberley as bird and bat
refuges is greater, against the backdrop of a harsher, more arid environment.
However, there are many habitats across Australia that provide refuge for species that
are otherwise widespread. For example, the mound springs and many other wetlands
of central Australia play an important refugial role for birds, as do wetlands across the
Gulf of Carpentaria in Queensland and the Northern Territory.
Kimberley mangroves, while providing an important role in maintaining
populations of both bird and bat species, nevertheless are not demonstrated to be
of greater importance than other refugial habitats across Australia, and
therefore do not have outstanding heritage value to the nation under criterion
(a) as refugia for mangal-dependent and mangal-obligate avifauna.
River refugia: There's something in the water
There is evidence that the river systems of the north Kimberley serve as refuges to
freshwater fish species, with a consequently high endemism found in several families.
With 18 species that are endemic to the region, the west Kimberley has the highest
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