Keighley, Miles
Description
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...[Show more] 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.
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