Biogeography of the vertebrates of the Cape Range peninsula, Western Australia

WA Museum Records and Supplements | Updated 9 years ago

Abstract: Thirty mammals, 84 reptiles, tlve amphibians and about 200 birds are known from the Cape Range peninsula. Biogcographic pattems of the extant terrestrial vertebrate fauna of the peninsula, particularly among the herpetofauna and avifauna, arc significantly related to landform units present on the peninsula.

The mammal fauna of the Cape Range peninsula ha, suffered numerous recent extinctions, but is not yet completely known (particularly for bats). With the exception of Petrogale lateralis, the 11 ground dwelling native mammals are common elsewhere in the arid and semi-arid north west of Western Australia. Most of the bats are northern species, but two southern species are present (Tadarida australia and Chalinolobus gouldii). Introduced mammals are well established in the area including goats and foxes.

In addition to ubiquitous species, the bird and reptile faunas arc typical of the semi-arid and arid north west and interior, although some south western species arc also present. Many species are represented on Cape Range peninsula by populations isolated from the main part of their conspecific distribution. Despite this, levels of endemism on the peninsula are low. Only two species, Lerista allochira (a skink confined to the limestone of the Cape Range) and the Grey Shrike-thrush (Colluricincla harmonica rufiventris) show specific and sub-specific endemism respectively within the Cape Range peninsula area.

Inter-tidal coastal flats and mangrove habitats are significant to many bird species occurring on the peninsula, although many of these are migratory. The rocky gorges of the Cape Range provide refuge for the Black Footed Rock Wallaby (Petrogale lateralis) and the frog Pseudophryne douglasi, both species which occupy scattered relietual ranges within the north west (P. lateralis also occurs in the south west of Western Australia) However, among the reptiles, aeolian units on the peninsula are much more significant biogeographically. Southern species at their northern limits on the peninsula are found on the white beach dunes of the western coast, while isolated populations of northern and central arid and semi-arid zone reptiles occur on the small areas of orange sand ridges found on the peninsula.

The Cape Range peninsula presents a unique combination of environments for the north west coast. Preeambrian units are absent, and the dissected limestone of the Cape Range is isolated from other rocky country by lowland sand plains, dune fields and heavier alluvial units. While the Cape Range peninsula is strongly connected southward to the sand ridge and sand plain units of the Gascoyne, the Giralia anticline effectively isolates the peninsula sand units from those to the north and east. This combination of different sandy habitats, the dissected limestone range, extensive inter-tidal habitats and a coastally ameliorated climate suitable to some southern and northern mesic zone species combine to maintain a diverse and concentrated suite of vertebrates.