606 KING EIDER (SOMATERIA SPECTABILIS) BROOD ECOLOGY: CORRELATES OF DUCKLING SURVIVAL Katherine R. Mehl 1,3 and Ray T. Alisauskas 2 1 University of Saskatchewan, Department of Biology, 112 Science Place, Saskatoon SK S7N 5E2, Canada; and 2 Prairie and Northern Wildlife Research Centre, Canadian Wildlife Service, 115 Perimeter Road, Saskatoon SK S7N 0X4, Canada Abstract.—Events during duckling growth can influence waterfowl population dynamics. To gain insight into King Eider (Somateria spectabilis) brood ecology , we monitored 111 and 46 individually marked ducklings from broods of 23 and 11 radiomarked King Eiders during 2000 and 2001, respectively . We used cap- ture–mark–resight data to model apparent survival of King Eider ducklings and broods, and multistratum analysis to estimate probabilities of (1) movement among habitats and (2) apparent survival of ducklings that used various habitats. In addi- tion, we recorded length of stay for 7 and 18 radiomarked females with failed nest- ing atempts during 2000 and 2001, respectively . Complete loss of individual broods accounted for 84% of all duckling mortality (106 of 126 mortalities), with most brood loss (74%; 17 of 23 broods lost) within the first two days afer hatch. Estimated appar- ent survival of ducklings to 24 days of age was 0.10 (95% CI: 0.05 to 0.15). Apparent survival of broods was estimated to be 0.31 (95% CI: 0.13 to 0.50). Our data suggested an interaction between female size and hatch date, whereby larger females whose ducklings also hatched earlier raised more ducklings than either small females or those with ducklings that hatched later . Overland brood movements ≥1 km occurred in both years, and survival was greatest for ducklings on smaller ponds away from the central nesting area at Karrak Lake, Nunavut. Females that experienced nest failure and total brood loss lef the study area earlier than females with surviving ducklings. Received 22 December 2004, accepted 4 June 2006. Key words: brood, duckling, habitat use, King Eider, Somateria spectabilis, survival. Écologie d’élevage des couvées de Somateria spectabilis : Corrélations avec la survie des canetons Résumé.—Les événements survenant au cours de la croissance des canetons peuvent influencer la dynamique des populations de sauvagine. Afin d’ en savoir plus sur l’écologie d’élevage des couvées chez l’Eider à tête grise (Somateria spectabilis), nous avons suivi 111 et 46 canetons marqués individuellement et appartenant à 23 et 11 femelles dotées d’émeteurs en 2000 et 2001, respectivement. Nous avons utilisé des données de capture–marquage-réobservation afin de modéliser la survie apparente des canetons et des couvées d’Eider à tête grise. Une analyse en multistrates a aussi été réalisée pour estimer les probabilités (1) de mouvement entre les habitats et (2) de survie apparente des canetons ayant utilisé différents habitats. De plus, nous avons enregistré la durée de séjour de 7 et 18 femelles dotées d’émeteurs et ayant échoué la nidification en 2000 et 2001, respectivement. La perte totale des couvées comptait pour 84% de toutes les mortalités de canetons (106 des 126 mortalités), la plupart survenant dans les deux premiers jours après l’éclosion (74%; 17 des 23 couvées disparues). La 3 Present address: Ducks Unlimited Canada, 6 Bruce Street, Mount Pearl, Newfoundland A1K 4T3, Canada. E-mail: kr_mehl@ducks.ca The Auk 124(2):606–618, 2007 © The American Ornithologists’ Union, 2007. Printed in USA. Downloaded from https://academic.oup.com/auk/article/124/2/606/5562608 by guest on 26 September 2022