On the isolated population of Lewin’s Honeyeater (Meliphaga lewinii amphochlora) from the McIlwraith Range uplands, Cape York Peninsula, Australia: estimates of population size and distribution

Abstract

Subspecies amphochlora of the Lewin’s Honeyeater (Meliphaga lewinii) is confined to a small isolated population in the McIlwraith Range, Cape York Peninsula, north-eastern Australia. The population is poorly known but is thought to be restricted to elevations above 500 m. We aimed to establish reliable estimates of population size and geographical range to enable a better evaluation of the conservation status of the subspecies. We also sought to quantify elevational patterns of density within the range and test the hypothesis that climate is the dominant factor governing range limits. We estimate the area of occupancy to be 183 km2, pending the investigation of three small fragments of predicted suitable habitat in mountain ranges to the north of the McIlwraith Range. Our count data indicate that the population probably consists of fewer than 5000 individuals (best estimate = 4666 individuals, 95% confidence intervals (CI) = 2868–7591). Highest densities were observed in a geographically limited subset of the range above 650 m. Independent validation of our species-climate distribution model suggests that the restricted spatial distribution of the subspecies is attributable to climate associations and implies that warm temperatures in particular act to restrict the lower elevational limit of the subspecies. We discuss the implications of these findings for the future survival of M. l. amphochlora in the context of contemporary climate warming.