TY - JOUR
T1 - Habitat-specific clutch size and cost of incubation in common eiders, Somateria mollissima
AU - Kilpi, Mikael
AU - Lindström, Kai
PY - 1997
Y1 - 1997
N2 - 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.
AB - 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.
KW - Common eider
KW - Habitat type
KW - Optimal clutch size
KW - Relative reproductive effort
KW - Weight loss
UR - http://www.scopus.com/inward/record.url?scp=0030829411&partnerID=8YFLogxK
U2 - 10.1007/s004420050238
DO - 10.1007/s004420050238
M3 - Article
AN - SCOPUS:0030829411
SN - 0029-8549
VL - 111
SP - 297
EP - 301
JO - Oecologia
JF - Oecologia
ER -