Interclutch variation in the size of free-living willow ptarmigan (Lagopus lagopus alexandrae) eggs was examined at Chilkat Pass, British Columbia. Egg volume (19.9 ± 0.1 cm3; mean ± 1 SE) fell within the range reported for other populations of ptarmigan. Most of the egg-size variation (56.0%) was explained by differences among females, but renesting ability and nesting attempt were also important. The age-class of females and timing of nest loss had no effect on egg-size variation. Females that laid replacement clutches produced eggs in their first nesting attempts (n = 12 females, 102 eggs) that were 4.6% (0.9 cm3) larger than the eggs of birds that did not renest (n = 12 females, 95 eggs). Clutch size decreased between nesting attempts, and there was a 1.6% (0.3 cm3) increase in egg size (n = 12 females, 65 eggs). We suggest that future studies examining the influence of nesting attempt on egg size should also control for renesting ability.
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Sandercock et al. (1994) studied this question.