Using playback and habitat models to estimate the distribution and population size of the critically endangered Crow Honeyeater, Gymnomyza aubryana, in New Caledonia

The Crow Honeyeater (Gymnomyza aubryana) is a critically endangered bird, endemic to the main island of New Caledonia, but it is poorly known owing to its elusive nature. We conducted playback surveys to assess the distribution, habitat preferences and vocal activity of the species. Crow Honeyeaters responded well to playback, with response rates reaching 67% at times. Our surveys revealed two distinct populations, separated by similar to 250km: one in the north of the island and the other, larger population in the south. The range of the northern population appears to be very small. Presence of the species was linked to rainforests growing on oligotrophic soils, primarily on ultramafic substrates. Approximately 315-700km(2) of suitable habitat for the species remains, corresponding to a maximum estimated population of 315-700 breeding pairs. The size and range of the Crow Honeyeater population is much smaller than previously assumed, and comprehensive management will be required to ensure its survival.