Varying foraging patterns in response to competition? A multicolony approach in a generalist seabird
Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self‐ and chick‐provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging beha...
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| Published in: | Ecology and evolution 2016-02, Vol.6 (4), p.974-986 |
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| Main Authors: | , , , |
| Format: | Article |
| Language: | eng |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | Reducing resource competition is a crucial requirement for colonial seabirds to ensure adequate self‐ and chick‐provisioning during breeding season. Spatial segregation is a common avoidance strategy among and within species from neighboring breeding colonies. We determined whether the foraging behaviors of incubating lesser black‐backed gulls (Larus fuscus) differed between six colonies varying in size and distance to mainland, and whether any differences could be related to the foraging habitats visited. Seventy‐nine incubating individuals from six study colonies along the German North Sea coast were equipped with GPS data loggers in multiple years. Dietary information was gained by sampling food pellets, and blood samples were taken for stable isotope analyses. Foraging patterns clearly differed among and within colonies. Foraging range increased with increasing colony size and decreased with increasing colony distance from the mainland, although the latter might be due to the inclusion of the only offshore colony. Gulls from larger colonies with consequently greater density‐dependent competition were more likely to forage at land instead of at sea. The diets of the gulls from the colonies furthest from each other differed, while the diets from the other colonies overlapped with each other. The spatial segregation and dietary similarities suggest that lesser black‐backed gulls foraged at different sites and utilized two main habitat types, although these were similar across foraging areas for all colonies except the single offshore island. The avoidance of intraspecific competition results in colony‐specific foraging patterns, potentially causing more intensive utilization of terrestrial foraging sites, which may offer more predictable and easily available foraging compared with the marine environment.
In a multiyear tracking study, we tested whether the foraging behaviors of incubating lesser black‐backed gulls differed between six island colonies varying in size (breeding pairs) and distance to mainland, and whether any differences could be related to the foraging habitats visited. Birds fed at terrestrial and marine habitats, although birds from colonies with larger sizes tended to utilize terrestrial habitats stronger than those from small‐size colonies. The clearly segregated foraging patterns among all studied colonies might be a strategy to avoid intraspecific competition, which might in turn lead to a more intensive utilization of terrestrial fo |
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| ISSN: | 2045-7758 2045-7758 |