Breeding Season Survival of Female Lesser Scaup in the Northern Boreal Forest

• Main Authors: Rodney W. Brook, Robert G. Clark
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 2004
• Subjects: Canada; Northwest Territories; Yellowknife; Arctic; Territoires du Nord-Ouest
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.564.4601; http://pubs.aina.ucalgary.ca/arctic/Arctic58-1-16.pdf

ABSTRACT. One hypothesis advanced to explain the decline in lesser scaup (Aythya affinis) populations during the past 20 years is that adult female survival has decreased. However, no survival probability estimates exist for the boreal forest, the region where most scaup breed. We captured and radio-marked female lesser scaup (n = 42) near Yellowknife, Northwest Territories, Canada, just before the breeding season in 1999 and 2000. Constant weekly survival probability was estimated using a Cormack-Jolly-Seber model (0.96). We extrapolate this rate to estimate survival probability for the nesting season (0.80, SE = 0.09), the period when females are at greatest risk of predation. Recent estimates of annual mortality (42%) suggest that about 50 % of annual female mortality occurs during the breeding season, a result similar to recent conclusions from studies of prairie-nesting lesser scaup. Further, our survival estimate provides information required to produce preliminary models of population dynamics for boreal lesser scaup, a step that could greatly improve our understanding of decline in this species. Key words: Aythya affinis, lesser scaup, boreal forest, breeding season survival, recapture probability, survival probability RÉSUMÉ. Une hypothèse qui a été avancée pour expliquer le déclin des populations du petit fuligule (Aythya affinis) au cours des 20 dernières années est que la survie de la femelle adulte a baissé. Il n’existe cependant aucune estimation de la probabilité de survie pour la forêt boréale, région où se reproduisent la plupart des fuligules. Juste avant la saison de reproduction en 1999 et 2000, on a capturé, près de Yellowknife dans les Territoires du Nord-Ouest, des fuligules femelles (n = 42) qu’on a équipées de radio-émetteurs. À l’aide du modèle de Cormack-Jolly-Seber, on a estimé la probabilité de survie hebdomadaire (0,96) sur une