Cultural diversity and meta-population dynamics in Australian palm cockatoos (Probosciger aterrimus); the legacy of landscape and biogeographic history

Abstract

Understanding dispersal dynamics is important for conservation of vulnerable species because they effect whether populations recover or disappear following decline or disturbance, especially in species with slow life-histories that cannot replenish quickly. Palm cockatoos have one of the slowest reproductive rates for any parrot, and likely face steep decline in at least one location on Cape York Peninsula (CYP), north-eastern Australia. Traditional methods of measuring dispersal, such as capture and fitting of tracking devices, identification markers or tissue sampling for genetic analyses, are inappropriate in this species due to their susceptibility to stress. While handling chicks for DNA sample collection does not cause harm, locating nests requires too much focused effort at spatial scales relevant for conservation. In this thesis, I assess the utility of cultural methods for determining population connectivity based on published literature, and employ a combination of cultural and genetic methods to assess connectivity among Australian palm cockatoo populations. I then use a landscape ‘resistance’ modelling approach based on electrical circuit theory to identify connectivity corridors. Finally, I use population viability analysis (PVA) to determine the effects of dispersal dynamics on viability for both individual populations and the combined meta-population in Australia. Based on the literature I concluded that geographic variation in cultural behaviour among populations of a species can help fill important knowledge gaps about their population level processes, especially when comparisons to similar species and alternative data are available. My assessments of vocal and genetic variation among populations revealed differentiation among populations on Cape York Peninsula, separating east coast palm cockatoos at Iron Range from other Australian populations with some evidence of gene flow between them. My landscape ‘resistance’ analysis identified the Great Dividing Range as a barrier, and rainforest patches as important corridors for interaction among separate populations. However, the level of connectivity we determined appears not to provide enough support via dispersal to buffer the decline predicted for Iron Range. Furthermore, other populations require much better reproductive success than data suggests for Iron Range if individuals dispersing to there are to be replenished. I emphasise the importance of managing local declines for the preservation of genetic and behavioural diversity in Australian palm cockatoos.