Increased use of intertidal resources benefits breeding success in a generalist gull species

O'Hanlon, N. J., McGill, R. A.R. and Nager, R. G. (2017) Increased use of intertidal resources benefits breeding success in a generalist gull species. Marine Ecology Progress Series, 574, pp. 193-210. (doi: 10.3354/meps12189)

Abstract

Determining how resource use impacts on a species’ demography is important, especially in habitats which are being altered by anthropogenic land-use change. If changes result in species consuming resources of reduced quality their demographic traits may be adversely affected. Generalist species are useful when investigating changes in resource availability as they can switch to alternatives if their preferred food becomes unavailable. For species that can forage on marine and terrestrial resources, it is often not known whether a switch from marine to terrestrial resources will have negative consequences. The herring gull, Larus argentatus, is one widespread generalist that opportunistically forages within marine and terrestrial habitats that are increasingly altered by humans. We determined marine and terrestrial resource use of gulls from eight colonies over two years across south-west Scotland and Northern Ireland using pellets and stable isotope analysis of chick feathers, which gave comparable results. Herring gulls in the study region used very little marine offshore resources but birds from colonies located in areas with sheltered coastlines, which provide abundant and diverse marine food from the intertidal zone, foraged more on marine intertidal resources. In contrast, colonies closer to built-up areas used more terrestrial resources. Herring gulls raised larger broods in colonies where they consumed a higher proportion of marine resource. Therefore, where generalist species, such as gulls, switch to an alternative resources that is available to them within their foraging range this may come at a cost of lower breeding success.

• Item Type: Articles
• Keywords: Anthropogenic impact, coastal, intertidal, herring gull, Larus argentatus, pellets, stable isotope.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: McGill, Dr Rona and O'Hanlon, Miss Nina and Nager, Dr Ruedi
• Authors: O'Hanlon, N. J., McGill, R. A.R., and Nager, R. G.
• Subjects: Q Science > QL Zoology
• College/School: College of Science and Engineering > Scottish Universities Environmental Research Centre; College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Research Group: Nager
• Journal Name: Marine Ecology Progress Series
• Journal Abbr.: MEPS
• Publisher: Inter Research
• ISSN: 0171-8630
• ISSN (Online): 1616-1599
• Copyright Holders: Copyright © 2017 Inter-Research
• First Published: First published in Marine Ecology Progress Series 574: 193-210
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
48920	1	IBIS (SCENE 2)	Colin Adams	European Commission (EC)	N/A	RI BIODIVERSITY ANIMAL HEALTH & COMPMED