Plastic ingestion by Flesh-footed Shearwaters, Puffinus carneipes, and Wedge-tailed Shearwaters, Puffinus pacificus

Abstract

The population of Flesh-footed Shearwaters, Puffinus carneipes, on Lord Howe Island, Australia, has decreased over recent decades. Known threats include long-line fishing and loss of nesting habitat. The recent occurrence of plastic debris in breeding colonies has raised concerns that plastic ingestion also may be contributing to the decline of this species. In this paper we investigate the extent of plastic ingestion by Flesh-footed and Wedge-tailed shearwaters, Puffinus pacificus, on Lord Howe Island. The remains offailed Flesh-footed Shearwater fledglings contained substantial quantities of plastics: up to 37 cm3, equivalent to at least 31% of proventricular capacity. Road-killed adults (n=21) had no plastic in their proventriculus. Proventricular contents of near-fledged birds, obtained by non-lethal means, showed that 79% of Flesh-footed Shearwaters and 43% of Wedge-tailed Shearwaters contained plastics, in volumes of up to 18.0 cm3 and 2.8 cm3, respectively. Plastic loads were significantly less in Wedge-tailed Shearwaters, the difference possibly due to different densities of plastic within the foraging locations of each species. The impact of plastic ingestion on the survival of Flesh-footed Shearwater chicks and fledglings, and the consequent impacts on the demography of the population are unknown and warrant further investigation.