Population densities and conservation status of Norfolk Island forest birds

Abstract

SummaryThree weeks of intensive surveys in Norfolk Island National Park in 2009 failed to find White-chested White-eye Zosterops albogularis and it was calculated that there was a less than 17% probability that a population of 10 birds had been overlooked. The last multi-observer record of this species was in 1978, and it is recommended that the species’ IUCN Red List status of “Critically Endangered” is tagged as “Possibly Extinct”. During these surveys, the population densities of seven bird species were calculated from 352 independent point counts. Causes of imprecision and bias were investigated, suggesting a small underestimation. Other species were recorded too infrequently, or their distributions were too biased, for analysis. The population densities of the extant endemic taxa were relatively high and suggest no current declines, and the population estimates were consistent with previous studies. This study recommends monitoring most species by point counts, or line transects if resources are limited, supplemented with specific monitoring of Tasman (Norfolk Island) Parakeet Cyanoramphus cookii, Pacific Robin Petroica multicolor, Southern Boobook Ninox novaeseelandiae and seabirds. Ongoing monitoring of these birds is needed to help inform management of the National Park and the island in general, given their small population sizes and their likely susceptibility to rat and cat predation, competition from alien species and drought.