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University Staff: Request a correction | Enlighten Editors: Update this recordĪlverson DL (1992) Commercial fisheries and the Steller Sea Lion (Eumetopias jubatus): the conflict arena. Reproduced in accordance with the copyright policy of the publisher
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G.Ĭollege of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative MedicineĬollege of Science and Engineering > Scottish Universities Environmental Research Centreįirst published in Marine Ecology Progress Series 574: 193-210 O'Hanlon, Miss Nina and McGill, Dr Rona and Nager, Dr Ruedi Item Type:Īnthropogenic impact, coastal, intertidal, herring gull, Larus argentatus, pellets, stable isotope. 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. Herring gulls raised larger broods in colonies where they consumed a higher proportion of marine resource. In contrast, colonies closer to built-up areas used more terrestrial resources.
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. 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. The herring gull, Larus argentatus, is one widespread generalist that opportunistically forages within marine and terrestrial habitats that are increasingly altered by humans. 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. Generalist species are useful when investigating changes in resource availability as they can switch to alternatives if their preferred food becomes unavailable.
If changes result in species consuming resources of reduced quality their demographic traits may be adversely affected. Determining how resource use impacts on a species’ demography is important, especially in habitats which are being altered by anthropogenic land-use change.