The Vertebrate Fauna of Houtman's Abrolhos (Abrolhos Islands), Western Australia.

Abstract

SUMMARY. Mammals.—The two indigenous species of Mammals are only found in the Wallaby Group, the Wallaby on both the large islands, the Rat, as far as is known, only on East Wallaby Island. The latter is probably, and the former certainly, subspecificailly distinct from the mainland species. Snakes.—The three species of snakes do not appear to differ from the mainland forms. At present two have been found only on West Wallaby Island and the third on East Wallaby Island. Lizards.—‐Four families are represented by some 19 species. The seven species of Geckonidæ iire only known from the Wallaby Group, the two species of Pygopodidæ only from West Wallaby Island, and the single species of Agamidæ from the Wallaby Islands and North Island. The Scincidæ are represented throughout the group, though we only met with the smaller species of Lygosoma outside the Wallaby Group; one of the larger forms, Egernia stokesi was, however, formerly plentiful on Rat Island. Froas.—Nothing is known no to the habitat of the two species recorded from the group. Birds.—of the 12 land‐birds recorded from the Abrolhos, four Kestrel, Robin, Song‐Lark, and Pipit) are certainly only casual visitors, five others (Rail, Crake, Kingfisher, Swallow, and White‐eye) are probably visitors From the mainland, though all but the Crake and Kingfisher have been known to breed; the remaining three are almost certainly residents. Of these, the Pigeon and the Quail are found in the Wallaby Group and on North Island, the Scrub‐Wren only on the Wallaby Islands. The two latter are subspecifically distinct from the mainland forms. Looking now of the different groups of islands we find that West Wallaby Islad has two snakes and two slow‐worms confined to it, East Wallaby Island has one snake and one rat confined to it, whilst the two Wallaby Islands possess subspecies of a wallaby and a bird peculiar to them. The Wallaby Islands, with North Island, possess also one lizard and two birds not found in the other groups, one of the birds being a subspecies peculiar to the group. This distribution strengly suggests that the whole land‐fauna of the group has been derived from the Wallaby Islands *. One of the chief features of the weather on the Abrolhos is the prevalence during the summer of “southerly busters,” estremely strong southerly winds. The presence of the two birds on North Island is thus easily accounted for, and it, is noteworthy that the one lizard which habitually climbs bushes is the one which has managed to reach that island. Doubtless at times the Lushes on the sand‐hills which it frequents are blown into the sea, and occasionally reach North Island. The fact that the smaller skinks are found on many of the small sandy islets seems to show that the sea is no great burrier to their distribution. Probably their eggs are not damaged by floating in sea‐water for some time. The larger Spiny‐tailed Skink, Egernia stokesi, is a favourite food of the Sea‐Eagles, and it is possible that individuals may be captured by them on the Wallaby Group and coppied to tha...

Stable social aggregations in an Australian lizard, Egernia stokesii

“…The gidgee skink (Egernia stokesii) is commonly described as gregarious (Alexander 1922;Swan 1990), and can distinguish chemical stimuli from group or non-group conspecifics . Genetic studies (Gardner 1999;Gardner et al 2000Gardner et al , 2001 have suggested a family structure within social groups.…”

A new species of the Aprasia repens species-group (Squamata: Pygopodidae) from Western Australia

“…Even surveys of historically well collected areas for reptiles, such as on the central west coast of Western Australia (Alexander 1922;Storr et al 1983;Maryan 2005), can lead to exciting discoveries of new species. Their detection on the Abrolhos Islands represented a major addition to the herpetofauna of this remote archipelago, an area that had been regularly visited and collected for nearly 100 years.…”

“…The herpetofauna of the Geraldton region (including the Houtman Abrolhos) is exceptionally diverse and has a long history of surveys (Alexander 1922;Storr et al 1983;Maryan 2005). More recently, additional surveys to document the herpetofauna have resulted in no new species being recorded for the Houtman Abrolhos, but several new records of species being found on individual islands (How et al 2004).…”

Genetic consequences of isolation: island tammar wallaby (Macropus eugenii) populations and the conservation of threatened species

“…NI is a more recently formed sand island and the resident tammar wallaby population must have either naturally dispersed from EWI and/or WWI, or been introduced. The first recorded observation of a tammar wallaby on NI was in 1928 following their introduction (source population unknown) as a potential food source for stranded fisherman (Alexander 1922;Storr 1960;Poole et al 1991). This introduction was thought to be unsuccessful and the population was subsequently reported extinct (Storr 1960).…”

“…West Wallabi Island (WWI) is the largest of the three (587 ha) and became separated from the adjacent East Wallabi Island (EWI: 307 ha) 6,000 years ago (Peltier 2004). EWI and WWI are continental islands and tammar wallabies became isolated from the mainland following rising sea levels 11,500 years ago at the end of the last glacial maximum (Alexander 1922;Storr 1965). They are geographically close (1.9 km apart) (GeoscienceAustralia 2005) and since much of this distance is exposed at low tide (BOM 2008) it is believed that wallabies can travel between them (Cooper and McKenzie 1997).…”