The demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa

I examined the demography and cooperative breeding behaviour of the rufous treecreeper, Climacteris rufa, in the south-west of Western Australia. Soci al organisation, breeding behaviour, reproductive success, survival and dis persal were measured over 3 years. The species lived in cooperatively breed ing groups of 2-7 individuals, which occupied a territory year round. Most groups comprised a primary male and female (probably breeding) and offsprin g from previous breeding seasons (helpers). Territory defence was variable, particularly during the breeding season when individuals would feed nestli ngs in adjacent territories. The social organisation of the species was bas ed on neighbourhoods of interacting territories. All group members provisio ned 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). Fle dgling and juvenile survival rates were relatively high (0.76 and 0.46 resp ectively), but adult survival rate (0.76) was comparable to that of other p asserines of the temperate Southern Hemisphere. Dispersal of juveniles appe ared to be female-biased. The demography of the rufous treecreeper was cons istent with other old endemic Australian passerines. High adult survival re sulted in few breeding vacancies for non-breeders and this is probably an i mportant factor in the evolution of cooperative breeding in the species. Co operative breeding also appears to be influenced by habitat saturation and a cost-benefit trade-off between remaining as a helper in high-quality terr itories and dispersing to poorer-quality territories where reproductive suc cess may be low.