Re ECF Project: 2014-02

Project Title: Population Status and Ecology of Yellow-crested Cockatoo (Cacatua sulphurea) in Hong Kong

Applicant: Dr Chu Lee Man of The Chinese University of Hong Kong

Total Approved Grant: $499,940

Duration: 1/3/2015 to 28/2/2017

Project Status/Remarks: Completed

Scope:
This project aims to:

  1. conduct a systematic census on the distribution and population of endangered yellow-crested cockatoo in urbanized areas of Hong Kong;
  2. elucidate its breeding ecology including breeding season, breeding behavior and reproductive success;
  3. investigate its particular social behavior such as flock foraging and communal roosting;
  4. examine its habitat preference or selection including nest selection and human disturbance; and determine the factors affecting its established success in the urban environment in Hong Kong.

Summary of the Findings/Outcomes:
Hong Kong has the largest exotic population of the endangered Yellow-crested cockatoo (Cacatua sulphurea) and the majority of the populations were distributed in the northern and western parts of Hong Kong. The research team conducted roost count on Hong Kong Island which had a mean population of 118 individuals, with the largest group in Hong Kong Park (maximum 110 and mean 83.8). Nocturnal roosting study in Central reveals that the annual mean roosting flock size was 78 with a peak number of 97 individuals. The birds shifted roosting sites seasonally, favored sites with relatively high human disturbance, which was probably related to predation avoidance, and preferred warmer sites on cold nights. Yellow-crested cockatoo showed its flexibility and adaptation to the local city environment. During the project period, 27 potential nest holes were observed. Although only half of the hollows were regularly used, it is far too early to conclude that nest hole availability was not a factor limiting population growth of the Yellow-crested cockatoo. There were no distinctive preferences of the cockatoos in Hong Kong in selecting their nests. The cockatoos are opportunistic foragers. The bird fed on various tree species with respect to their flowering and fruiting periods. Flowers and fruits were more favorite food than bark, branches and leaves for the birds. They had minimal harms to the fauna and their negative impacts are negligible as their population is small.