Habitat preferences, foraging behaviour and bycatch risk among breeding sooty shearwaters Ardenna grisea in the Southwest Atlantic

Bonnet-Lebrun, A.-S., Catry, P., Clark, T. J., Campioni, L., Kuepfer, A., Tierny, M., Kilbride, E. and Wakefield, E. D. (2020) Habitat preferences, foraging behaviour and bycatch risk among breeding sooty shearwaters Ardenna grisea in the Southwest Atlantic. Marine Ecology Progress Series, 651, pp. 163-181. (doi: 10.3354/meps13439)

Abstract

Pelagic seabirds are important components of many marine ecosystems. The most abundant species are medium/small sized petrels (<1100g) yet the sub-mesoscale (<10 km) distribution, habitat use and foraging behaviour of this group are not well understood. Sooty shearwaters (Ardenna grisea) are among the world’s most numerous. The majority inhabit the Pacific, where they have declined, partly due to bycatch and other anthropogenic impacts, but they are increasing in the Atlantic. To evaluate the sub-mesoscale habitat preferences (i.e. the disproportionality between habitat use and availability), diving behaviour and bycatch risk of Atlantic breeders, we tracked sooty shearwaters from the Falkland Islands during late incubation and early chick-rearing with GPS loggers (n = 20), geolocators (n = 10) and Time-Depth Recorders (n = 10). These birds foraged exclusively in neritic and shelf-break waters, principally over the Burdwood Bank, ~ 350 km from their colony. Like New Zealand breeders, they dived mostly during daylight, especially at dawn and dusk, consistent with the exploitation of vertically migrating prey. However, Falkland birds made shorter foraging trips, shallower dives, and did not forage in oceanic waters. Their overlap with fisheries was low and they foraged at shallower depths than those targeted by trawlers, the most frequent fishing vessels encountered, indicating that bycatch risk was low during late incubation/early chick-rearing. Although our results should be treated with caution, they indicate that Atlantic and Pacific sooty shearwaters may experience markedly differing pressures at sea. Comparative study between these populations, e.g. combining biologging and demography, is therefore warrented.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wakefield, Dr Ewan and Kilbride, Mrs Elizabeth
• Authors: Bonnet-Lebrun, A.-S., Catry, P., Clark, T. J., Campioni, L., Kuepfer, A., Tierny, M., Kilbride, E., and Wakefield, E. D.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Marine Ecology Progress Series
• Publisher: Inter Research
• ISSN: 0171-8630
• ISSN (Online): 1616-1599
• Copyright Holders: Copyright © The authors 2020
• First Published: First published in Marine Ecology Progress Series 651:163-181
• Publisher Policy: Reproduced under a Creative Commons Licence

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
171561		Seabirds and wind - the consequences of extreme prey taxis in a changing climate	Ewan Wakefield	Natural Environment Research Council (NERC)	NE/M017990/1	Institute of Biodiversity, Animal Health and Comparative Medicine