Avifauna of the Aiope River basin, Kunua District, north-west Bougainville Island

Abstract

We present the results of a bird survey undertaken in the Aiope (Sarime) River basin in the Kunua District of north-west Bougainville, Papua New Guinea, during October–November 2019. Birds were surveyed across an elevational gradient of nearly 1,800 m, from the coast at the mouth of the Aiope River to the catchment headwaters in the north-west Emperor Range. Seventy-nine bird species were recorded, including three-quarters of Bougainville's resident land and freshwater avifauna (76/102 species) and a high proportion of its island-endemic and Solomons-endemic taxa (genera, species and subspecies). Resident avifauna include three species listed as threatened on the IUCN Red List—Sanford's Sea Eagle Haliaeetus sanfordi, Fearful Owl Nesasio solomonensis and (provisionally) Yellow-legged Pigeon Columba pallidiceps—nine Near Threatened species and two species that are protected under Papua New Guinean law. Forest supports 84% of the recorded resident bird species, most of which are forest-dependent, including all island-endemic taxa and all species of conservation concern apart from the Near Threatened Woodford's Rail Nesoclopeus woodfordi. Forest extent and condition improved with increasing elevation along the surveyed route; upper hill zone forest provides a narrow band of suitable habitat for a suite of lowland and hill forest species that were locally formerly more common across a broader altitudinal range. Elevational range extensions are reported for six species, and the vocalisations of Solomons Frogmouth Rigidipenna inexpectata are described from Bougainville for the first time.