Climacteris

Abstract: Certain birds, usually associated with the mallee and sclerophyllous woodlands of south-western Australia, south-eastern Australia and Eyre Peninsula, also occur in the Great Victoria Desert, viz Glossopsitta porphyrocephalu, Neophema splendida, Cinclosoma castonotum, Myiagra inquieta, Microeca leucophaea, Pachysephala inortata, Climacteris rufa, Pardalotus xanthopygus, Strepera versicolor and Gymnorhina tibicen. The distribution, habitats and subspecific status of these species are discussed. The Great Victoria Desert is an avenue for the continuous distribution of these birds between Eyre Peninsula and the Southwest. Populations of most of these species on the eastern and western sides of the Nullarbor Plain have not diverged subspecifically from one another.

Abstract: The present paper determines the status and range of forms in the genus Climacteris Temminck (tree-creepers) formerly regarded as species; it also reviews infraspecific variation, re-defines races, and is a detailed study of speciation in the genus. Climacteris is a most interesting genus in the information it yields with respect to speciation, Forms occur that represent the full range of intermediate stages right up to the one that has demonstrated its specific distinctness by secondarily contacting the parental stock without interbreeding. The number of forms with the "potential" of developing into new species is unusually high, 0.8 per species in Australia, or 1.5 for Australia and New Guinea combined, The fundamental isolating barriers are tracts of arid country that cause extensive gaps in the habitats to which the various species are adapted. This presupposes an initial climatic deterioration which isolated remnant populations in "refuges", a theory that has already been introduced into ornithology by Gentilli (1949), Mayr (1950), and Serventy (1951). Climacteris differs from the related genus Neositta (nuthatches), studied by Mayr (1950), for in the latter a secondary climatic improvement has led to an increase in range and multiple hybridization. In Climacteris there is evidence of some secondary spread but, with one exception, distinctive geographically representative forms are still isolated.

Abstract: I examined the demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa, in the south-west of Western Australia. Social organisation, breeding behaviour, reproductive success, survival and dispersal were measured over 3 years. The species lived in cooperatively breeding groups of 2–7 individuals, which occupied a territory year round. Most groups comprised a primary male and female (probably breeding) and offspring from previous breeding seasons (helpers). Territory defence was variable, particularly during the breeding season when individuals would feed nestlings in adjacent territories. The social organisation of the species was based on neighbourhoods of interacting territories. All group members provisioned nestlings, and the primary male and female significantly reduced their provisioning effort as the number of helpers increased. Total nest success for the 3 years was 78% and mean annual productivity was 2.1 (0.18). Fledgling and juvenile survival rates were relatively high (0.76 and 0.46 respectively), but adult survival rate (0.76) was comparable to that of other passerines of the temperate Southern Hemisphere. Dispersal of juveniles appeared to be female-biased. The demography of the rufous treecreeper was consistent with other old endemic Australian passerines. High adult survival resulted in few breeding vacancies for non-breeders and this is probably an important factor in the evolution of cooperative breeding in the species. Cooperative breeding also appears to be influenced by habitat saturation and a cost–benefit trade-off between remaining as a helper in high-quality territories and dispersing to poorer-quality territories where reproductive success may be low.

Abstract: The present paper discusses and determines the status of a range of forms and species in the genus Amytornis Stejneger (Australian grass-wrens), reviews infraspecific variation and re-defines races, and makes a study of speciation in the genus. In demonstrating the various stages in the speciation process Amytornis provides a parallel with Climacteris Temminck (Keast 1957). The genus is particularly rich in distinctive isolated forms that, though they have never had their true status tested by contacting the parental stocks, are nevertheless so different that, if normal taxonomic procedure be applied, they must be regarded as species. There is one demonstration of the ultimate stage in the speciation process, that of two former isolates secondarily coming together and demonstrating their distinctness by failing to interbreed. Amytornis contrasts with Climacteris in that it is fundamentally a desert genus, with spinifex the basic habitat. Hence isolation of populations would appear to have resulted, in the main, not from increasing aridity, but as a result of the invasion of former spinifex or porcupine grass areas by savannah grassland (an unsuitable habitat as it provides cover for only part of the year). Changes in the colour and colour pattern of the birds and in size and bill form (inferring a change in the food) of Amytornis provide, to a degree, a continental example of the kind of speciation seen in some island archipelagos, e.g. Galapagos Is. (Lack 1947). The application of Gloger's and Bergmann's ecogeographical rules to members of the genus Amytornis is discussed.