Second North American Sea Duck Conference - Patuxent Wildlife ...
Second North American Sea Duck Conference - Patuxent Wildlife ...
Second North American Sea Duck Conference - Patuxent Wildlife ...
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SECOND NORTH AMERICAN SEA DUCK CONFERENCE<br />
ARE FEMALE COMMON EIDERS (SOMATERIA MOLLISSIMA) CAPITAL<br />
OR INCOME LAYERS?<br />
Yves Rigou and Magella Guillemette<br />
Département de biologie, Université du Québec à Rimouski, 300 allée des Ursulines, Rimouski,<br />
Québec G5L 3A1, Canada; yves.rigou@uqar.qc.ca<br />
One nesting phase that is particularly costly for waterfowl species is the production of the clutch.<br />
The female needs to gather a large amount of food in order to transfer nutrients (from endogenous<br />
reserves or directly from the food) to the growing follicles. In this paper, we test the idea that (1)<br />
female common eiders transfer nutrients directly from food ingested to ovary growth during prelaying<br />
and, (2) females feed during laying. Using published information from three studies, (1)<br />
body condition of pre-laying females was assessed in relation to follicular growth, (2) body mass<br />
of females and, (3) nest attendance pattern while laying are reported. Somatic body mass and body<br />
composition of birds collected around a nesting colony, in the Baltic sea, did not change significantly<br />
in relation to three categories of ovary growth. Sixty-four percent of the females studied lost body<br />
mass, twenty-seven percent had a constant mass and nine percent gained mass while laying resulting<br />
in an average decrease of body mass of 39 g (SD ± 63), which is less than the average mass of a fresh<br />
laid egg. Attendance patterns showed that females left the nest for most of the night and a part of the<br />
day during the first days of the laying phase and that time spent off the nest decreased steadily from<br />
the first to the last egg laid in the clutch. Altogether, these results suggest that (a) the clutch produced<br />
by female common eiders nesting in the Baltic is composed of nutrients derived mainly from food<br />
collected around the breeding colony, (b) females continue to feed during laying which is consistent<br />
with the fact that (c) ample time is spent off the nest during the laying phase.<br />
108 ANNAPOLIS, MARYLAND, USA NOV. 7-11, 2005
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