Protected by dragons: density surface modeling confirms large population of the critically endangered Yellow-crested Cockatoo on Komodo island

Intense trapping of the critically endangered Yellow-crested Cockatoo Cacatua sulphurea  for the International pet trade has devastated its populations across Indonesia such that populations >100 individuals remain at only a handful of sites. We combined distance sampling with density surface modeling (DSM) to predict local densities and estimate total population size for one of these areas, Komodo Island, part of Komodo National Park (KNP) in Indonesia. We modeled local density based on topography (topographic wetness index) and habitat types (percentage of palm savanna and deciduous monsoon forest). Our population estimate of 1,113 (95% CI: 587–2,109) individuals on Komodo Island was considerably larger than previous conservative estimates. Our density surface maps showed cockatoos to be absent over much of the island, but present at high densities in wooded valleys. Coincidence between our DSM and a set of independent cockatoo observations was high (93%).
Standardized annual coun...