Long-term ecological change in a conservation hotspot: the fossil avifauna of Mé Auré Cave, New Caledonia

Abstract

Through the continuing accumulation of fossil evidence, it is clear that first human arrival on islands around the world was linked to a rise in the extinction rate for vertebrates. Bones in human-era fossil sites can also reveal changes in the composition and structure of ecological communities due to human environmental impacts. New Caledonia is a large and biogeographically distinct island in the southwest Pacific and is considered a critical priority for biodiversity conservation. We examined fossil birds from the Me Aure Cave site (WMD007), located in lowland dry forest on the west coast of New Caledonia. Accumulation of bird skeletal material in the cave was primarily through deposition in barn owl (Tyto alba) pellets. The site recorded the island-wide extinction of two species and extirpation of at least two other species from the lowlands in the past 1200 years. Species richness of birds in the stratigraphic deposit was quite high, reflecting the catholic diet of barn owls on islands, and many species have continued to persist near the site despite loss and degradation of the dry forest. However, we found substantial turnover in relative abundance of species in the cave deposit, with edge and open country birds becoming more common through time. These changes may reflect the severe reduction of dry forest habitat during the colonial period. This work provides a temporal record of avifaunal and environmental change in the threatened dry forest habitat that should be particularly informative for ongoing conservation and restoration efforts.