First investigations of the consumption of seal carcasses by terrestrial and marine scavengers

Quaggiotto, M.-M. , Burke, L.R., McCafferty, D.J. and Bailey, D.M. (2016) First investigations of the consumption of seal carcasses by terrestrial and marine scavengers. Glasgow Naturalist, 26(3), pp. 33-52.

Abstract

Marine mammal carrion contains a large amount of nutrients and energy of potential value to terrestrial and marine scavengers, but its impact on coastal habitats has not been studied. This study aimed to provide a detailed documentation of the fate of two grey seal (Halichoerus grypus) pup carcasses, one placed on the shore of Little Cumbrae and one at a depth of 6 m off Great Cumbrae, Firth of Clyde, and a record of the changes in the carcasses and the succession of scavengers using these resources. The carcasses were monitored using time lapse and/or motion-activated cameras. On the shore, great black-backed gulls, juvenile gulls and ravens fed on the carcass and there was a distinct shift in the relative proportions of the bird groups feeding over the period observed. Herring gulls spent significantly less of their time at the carcass feeding than other birds, while lesser black-backed gulls were not observed scavenging despite being common on the island. Over the six week period of observation, more than 90% of the carcass was consumed. However, the deployment of the carcass did not influence the spatial and temporal distribution of the scavenging birds. The underwater carcass was monitored for two periods of two weeks and one week respectively. In the first period Echinodermata (dominated by Asterias rubens) had the highest maximum number of individuals at the carcass, followed by Actinopterygii (fish) and Malacostraca (crabs). Numbers of fish and starfish dropped in the second period, while crustaceans were present in similar numbers as previously. The daily mass loss of the carcasses was 0.56 and 0.07 kg day-1 in the terrestrial and marine ecosystems respectively. Both the terrestrial and marine experiments displayed evidence of bacterial activity. In the absence of any previous detailed study, the present work provides important insights into the roles of seal carcasses in coastal systems, especially in an era when carrion from fisheries discards will become increasingly unavailable.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: McCafferty, Dr Dominic and Bailey, Dr David and Quaggiotto, Dr Martina
• Authors: Quaggiotto, M.-M., Burke, L.R., McCafferty, D.J., and Bailey, D.M.
• College/School: College of Medical Veterinary and Life Sciences > School of Life Sciences; College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Glasgow Naturalist
• Publisher: Glasgow Natural History Society
• ISSN: 0373-241X
• Copyright Holders: Copyright © 2016 The AuthorsGlasgow Natural History Society
• First Published: First published in Glasgow Naturalist 26(3):33-52
• Publisher Policy: Reproduced with the permission of the publisher.