ABSTRACT
Long-term monitoring of threatened species often reveals processes undermining population recovery that may not be evident over shorter timeframes. When populations are small and isolated, normal behaviours such as dispersal may cause the loss of certain demographic stages if compensatory immigration no longer occurs. Social interactions that facilitate mate pairing can become rare, reducing the likelihood of successful breeding pairs establishing. Against a backdrop of habitat loss and degradation, these factors may make population recovery difficult to achieve. We present 15 years of monitoring data from the Central Coast of NSW targeting a small population of endangered Bush Stone-curlews Burhinus grallarius. The monitoring, undertaken by volunteers, collected breeding and banding observations between 2003 and 2018. Taken together, the data show that the number of breeding pairs fluctuates between 1 and 6, and can increase relatively quickly. However, juvenile dispersal south to highly urbanised and dangerous sites in Sydney has become a population ‘sink’, undermining population recovery. The long-term banding observations have been fundamental to understanding how juvenile dispersal affects Bush Stone-curlew population dynamics. We suggest translocating pairs to ‘stepping stone’ sites to the north of the population to exploit dispersal behaviours and enhance connectivity between the Central Coast population and breeding pairs around Port Stephens. We strongly urge the continuation of monitoring in conjunction with local habitat conservation and management to work towards sustainable and resilient Bush Stone-curlew populations.
