Systematics of the reed-warblers of the Tuamotu Archipelago, eastern Polynesia

Abstract

The Tuamotu Reed-Warbler (Acrocephalus atyphus) is a small insectivorous passerine endemic to eastern Polynesia in the Pacific Ocean. To complement a previous study of the phylogeography of this species based on molecular data, we undertook an analysis based on morphological characters taken from study skins and live birds and propose a new classification for the Tuamotu Reed-Warbler. Three of the six subspecies previously recognised, eremus, palmarum and niauensis, can be diagnosed by both morphological and genetic characters and all are found on uplifted coral islands with a peculiar geomorphology (a shallow or absent lagoon) and elevations higher than average for Tuamotu atolls. Conversely, morphological and molecular analyses suggest that all low-lying atoll populations should be merged into a single taxon, atyphus. Finally, we suggest priorities for conservation for this endemic bird. This study provides an evaluation of the morphological variation of a terrestrial bird across the largest chain of atolls in the world.