Are late-spring boreal lesser scaup (Aythya affinis) in poor body condition / Jean-Michel DeVink, Robert G. Clark, Stuart M. Slattery, and David L. Trauger.

Includes bibliographical references (pages 291-298).

I�� ma��� waterfow�� species�� fema�e�� i�� bette�� bod�� co�ditio�� hav�� greate�� reproductiv�� succesIn many waterfowl species, females in better body condition have greater reproductive success �� tthanha�� tthosehos�� iin�� ppooroo��
condition ; thus, large -scale changes in body condition could in fluence species ’ population dynamics . Indices of annual productivity
have decreased in Lesser Scaup (Aythya affinis), and the “spring condition ” hypothesis (SCH) has been proposed to account for poor pro -
duction and low populations in this species . We compared nutrient reserves of female Lesser Scaup and Ring -necked Duc ks (A. collaris)
collected during the breeding season at multiple sites in the Canadian boreal forest, the region where ~70% of both species breed and
where they have had contrasting population trends for the past 25 years . Lesser Scaup tended to carry greater somatic lipid but slightly
lower protein reserves than Ring -necked Duc ks, after controlling for si ze. The proportion of females developing follicles was similar
in both species, though Lesser Scaup initiated egg development later and exhibited less temporal variance in nesting date than Ring -
necked Duc ks. We also directly tested the SCH by comparing contemporary arrival and prebreeding body masses of Lesser Scaup with
historical values at one boreal -forest site . However, body masses of Lesser Scaup collected in 2003–2004 were comparable to those of
Lesser Scaup collected at Yellow knife, Northwest Territories, during 1968–1970. Overall, our results suggest that currently, body condi -
tion of boreal -breeding Lesser Scaup is relatively similar to that of Ring -necked Duc ks and to historical levels for Lesser Scaup . Future
studies of factors that limit recovery of Lesser Scaup should examine migration patterns and the effects of climate change on the timing
of both energetic requirements in Lesser Scaup and food -resource availability .