Changes in feeding behaviour and reproductive success in the Common Guillemot Uria aalge on the island of Stora Karlsö

Authors

  • Henrik Österblom Department of Vertebrate Zoology, Swedish Museum of Natural History
  • Olof Olsson

DOI:

https://doi.org/10.34080/os.v12.22836

Keywords:

foraging ecology, breeding biology, predator-prey interaction, breeding success, fledging success, parental care, predation

Abstract

We studied the feeding behaviour and reproductive success in Common Guillemots Uria aalge at the island of Stora Karlsö to reveal effects of an increased density of the prey fish Sprat Sprattus sprattus. Feeding rates were almost twice as high in 1998 (4.3 feeds/chick/day) as in 1975 (2.2 feeds/chick/day), and feeding trips were short. The adult birds spent a large proportion of the day together at the site during the chick–rearing period, indicating that the birds were not under significant food stress. Contrary to what we had expected, reproductive success was lower in 1998 and 1999 (0.671, SE = ±0.045, n = 2) than in 1974–1977 (0.803, SE = ±0.010, n = 4) and chick survival and age at fledging was unchanged despite the increase of available prey. We speculate that the condition (nutritional value), rather than the abundance of Sprat, has been important in changing the Guillemots feeding behaviour. The study indicates that the reason for the observed lower reproductive success was lower egg survival, most likely an effect of an increased predation pressure from Herring Gulls Larus argentatus.

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Published

2002-04-01

How to Cite

Österblom, H., & Olsson, O. (2002). Changes in feeding behaviour and reproductive success in the Common Guillemot Uria aalge on the island of Stora Karlsö. Ornis Svecica, 12(1–2), 53–62. https://doi.org/10.34080/os.v12.22836

Issue

Section

Research Papers