Seasonal variation in pre-fledging survival of lesser scaup Aythya affinis : Hatch date effects depend on maternal body mass /
Material type:
TextSeries: Journal of Avian Biology. 43(1) 68-78 Publication details: 2012.Description: illustrations ; 28 cmLOC classification: - GUR
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Includes bibliographical references (pages 76-78).
Among temperate-breeding birds, off spring survival and reproductive success are often inversely related to timing of breeding.
Th e mechanisms that produce seasonal declines in off spring survival are not fully understood but may be related to
temporal changes in parental quality, environmental quality, or both. We analyzed data for lesser scaup Aythya affi nis to
evaluate hypothesized eff ects of parental quality and date on pre-fl edging survival. Maternal quality, as indexed by body
mass, did not have an independent eff ect on off spring survival in this species. Maternal body mass did not decline seasonally
and did not have an independent eff ect on duckling survival. Although we did not detect an independent eff ect of
hatch date on duckling survival, duckling survival declined seasonally for broods raised by lightweight females, indicating
an interactive eff ect of maternal mass and date. We hypothesize that this interaction may be driven by seasonally declining
food resources coupled with the infl uence of female condition on the ability to monopolize food resources or remain attentive
to the brood. We also tested morphological predictions of the date hypothesis by examining physical characteristics of
ducklings. When corrected for age and size, late-hatched ducklings tended to have marginally larger digestive systems and
smaller leg muscles than did early-hatched birds. Abundances of intestinal parasites acquired through diet decreased marginally
in late-hatched ducklings. Results for digestive system and parasite infection patterns suggested that later-hatched
broods may shift diets, consistent with a contribution of environmental factors to seasonal variation in off spring survival.
Taken together, our results suggest that both female attributes and environmental conditions may influence seasonal patterns
of off spring survival in this species.