Alaska Science Center
The fledging of common and thick-billed murres on Middleton Island, Alaska
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Product Type: Journal Article
Authors: Hatch, S. A.
A 16-fold increase in the population of murres on Middleton Island occurred in 22 years or fewer. The breeding schedules of Common and Thick-billed murres were similar in 1978, with young of both species leaving the cliffs between about 20 July and 16 August. Chicks frequently spent one or more days in fresh water ponds after fledging. Considerable mortality occurred in this situation, especially among Thick-billed Murres. That fledging weight may affect the survival of newly-fledged chicks was indicated two ways: (1) fledging weight was higher among chicks that made it to sea than in chicks that remained in the ponds and died; (2) the number of days survived by birds of the latter group was positively correlated with their fledging weights. The nestling period seems to be further governed by feather development relative to body weight, since wing length and wing-loading are more constant among fledglings than weight.