Habitat selection and specialisation of Herring Gulls during the non-breeding season
Author(s): O'Hanlon, N.J., Thaxter, C.B., Burton, N.H.K., Grant, D., Clark, N.A., Clewley, G.D., Conway, G.J., Barber, L.J., McGill, R.A.R. & Nager, R.G.
Published: March 2022 Pages: 17pp
Journal: Frontiers in Marine Science Volume: 9
Article No.: 816881
Digital Identifier No. (DOI): 10.3389/fmars.2022.816881
New collaborative BTO research has used GPS to provide insights into the movements and habitat needs of Herring Gulls outside the breeding season. Researcher fixed GPS tags to 20 Herring Gulls breeding at four colonies in southwest Scotland (Oronsay, Islay, Pladda and Lady Isle) and one colony in northwest England (Walney) to better understand this Red-listed species of conservation concern.
During the non-breeding season, Herring Gulls used a range of habitats as would be expected for this opportunistic generalist species, that can survive on a wide variety of different foods. However, habitats were not used randomly based on their availability, with habitat selection differing between geographical regions and between individuals in the same region. Although Herring Gulls showed a preference for intertidal habitat in all regions, a mix of forging habitats, including grassland and farmland, were important over the course of the non-breeding season.
Although several individuals stayed close to their breeding colony, most migrated in a south-easterly direction (up to 190 km from their colony) and kept moving to different areas through the non-breeding season. Individuals also differed in the habitats they selected, with moderate habitat specialisation, indicating that resource use was flexible across time and space. This level of habitat and spatial segregation, as well as each individual gull’s distribution over a broad range of habitats and space, may help reduce competition for limited resources and buffer populations from localised anthropogenic pressures (for example, coastal development) during the non-breeding season.
The results also highlight that the habitat preferences and movement patterns of generalist species cannot in fact be generalised, even between nearby regions, which has implications for appropriate regional-specific spatial planning and conservation management.
NotesThe authors thank the technical support of the GPS-devices from Gary Brodin at PathTrack and Nosrat Mirzai, and Ewan Wakefield and Paul Johnston for statistical advice. Thanks to John Hartley (Hartley Anderson Ltd), Emma Cole, Mandy King, Sophie Thomas and James Burt (DECC), and the late Mark Rehfisch (BTO) for support. Angus Lothian, Terry Southall, and the RSPB Oronsay Staff helped with fieldwork in Scotland. Thanks to Cumbria Wildlife Trust and Natural England for permissions and Emily Scragg for help with fieldwork in northwest England.
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