Taylor & Francis Group
Browse
temu_a_1659105_sm8992.docx (3.37 MB)

Seashell and debris ingestion by African penguins

Download (3.37 MB)
journal contribution
posted on 2019-10-07, 22:18 authored by Ralph Eric Thijl Vanstreels, Lorien Pichegru, Maya C. Pfaff, Albert Snyman, Bruce M. Dyer, Nola J. Parsons, David G. Roberts, Katrin Ludynia, Azwianewi Makhado, Pierre A. Pistorius

African penguins (Spheniscus demersus) are pursuit-diving seabirds endemic to the coast of southern Africa. In this study, we investigate the presence of seashells and anthropogenic debris (e.g. plastic, glass, nylon) in the stomach contents of adult African penguins, as determined from sampling of live penguins through the water off-loading technique (n = 4,793) and from post-mortem examination of penguin carcases (n = 159). Seashells were present in stomach contents sampled from 106 live (2.2%) and three dead (1.9%) penguins. Seashells originated from a variety of intertidal and subtidal organisms including molluscs, barnacles and bryozoans, and the eroded condition of the shell fragments suggests that they were picked up from shell deposits on the beach or in the surf zone. Seashell ingestion appears to be more frequent in the months of peak egg laying. A subset of stomach samples from known-sex individuals revealed that seashells were only present in the stomachs of adult females. In post-mortem examination, the presence of seashells in the stomach was accompanied by anatomical evidence that egg laying was imminent or had recently occurred. Anthropogenic debris was found in one (0.6%) and eight (0.2%) stomach content samples obtained from dead and live penguins, respectively. In some cases, the ingestion of anthropogenic debris co-occurred with that of seashells, and their size and shape were similar. Our findings demonstrate that adult female African penguins occasionally ingest seashells, possibly as a calcium supplementation strategy, and raise concern that in doing so they may also accidentally ingest anthropogenic debris.

Funding

SANCCOB is supported by a wide range of local and international donors including international zoos and aquaria, foundations and trusts, corporations and individuals.

History