Seasonal variation in pre-fledging survival of lesser scaup Aythya affinis: hatch date effects depend on maternal body mass

摘要: Among temperate-breeding birds, offspring survival and reproductive success are often inversely related to timing of breeding. The mechanisms that produce seasonal declines in not fully understood but may be temporal changes parental quality, environmental or both. We analyzed data for lesser scaup Aythya affinis evaluate hypothesized effects quality date on pre-fledging survival. Maternal as indexed by body mass, did have an independent effect this species. mass decline seasonally duckling Although we detect hatch survival, declined broods raised lightweight females, indicating interactive maternal date. hypothesize interaction driven declining food resources coupled with the influence female condition ability monopolize remain attentive brood. also tested morphological predictions hypothesis examining physical characteristics ducklings. When corrected age size, late-hatched ducklings tended marginally larger digestive systems smaller leg muscles than early-hatched birds. Abundances intestinal parasites acquired through diet decreased Results system parasite infection patterns suggested later-hatched shift diets, consistent a contribution factors variation Taken together, our results suggest both attributes conditions