, Volume 111, Issue 3, pp 297–301

Habitat-specific clutch size and cost of incubation in common eiders, Somateria mollissima

  • Mikael Kilpi
  • Kai Lindström

DOI: 10.1007/s004420050238

Cite this article as:
Kilpi, M. & Lindström, K. Oecologia (1997) 111: 297. doi:10.1007/s004420050238


Common eiders, Somateria mollissima, breed on two types of island in the Northern Baltic: open, sparsely vegetated islands and wooded islands with dense mixed forests. On open islands 79.8% of the nests were on open cliffs, exposed to wind and rain whereas on wooded islands 91.7% of the nests were sheltered inside dense spruce and pine thickets. We found that clutch size on open islands was significantly smaller than on wooded islands. Females started breeding simultaneously in the two habitats and they were similar in body size as measured by the length of the radio-ulna. During incubation females on open islands lost weight at a faster rate than females on wooded islands (34 g/day and 19 g/day, respectively). Heat loss is faster on open than wooded islands and therefore we suggest that the faster weight loss of females on open islands result from thermodynamically adverse incubation conditions. Because the eider is an extreme capital breeder, energy used for egg production cannot be used for incubation. To sustain a higher incubation cost on open islands, the optimal clutch size is therefore lower than on wooded islands.

Key words Optimal clutch size Habitat type Relative reproductive effort Weight loss Common eider 

Copyright information

© Springer-Verlag Berlin Heidelberg 1997

Authors and Affiliations

  • Mikael Kilpi
    • 1
  • Kai Lindström
    • 1
  1. 1.Department of Ecology and Systematics, Zoological laboratory, University of Helsinki, POBox 17, FIN-00014 Helsinki, Finland Fax: +358-0-191 7492; e-mail: Kai.Lindstrom@Helsinki.fiFI

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