Molt Migration in Relation to Breeding Success in Greater Snow Geese

Abstract

ABSTRACT. We describe summer migratory movements by female greater snow geese (Chen caerulescens atlantica) breeding on Bylot Island, Nunavut. We followed 121 radio-collared females between 1997 and 2001 to determine the frequency and timing of their departure from the colony in relation to breeding status, nesting success, and molting chronology. We found that 90% (n = 51) of non-breeders (no nest found) and 97% (n = 29) of failed nesters (nest destroyed or abandoned before hatch) departed the island before molting. The few non-breeders that remained on Bylot Island all summer molted earlier than adults with young, and they appeared to initiate the fall migration before breeding geese. In contrast, only 2% of successful nesters (n = 41) left Bylot Island to molt, and those that did presumably had lost their offspring in the early stages of brood rearing. Thus, the occurrence of a molt migration in greater snow geese appears to be strongly dependent on reproductive status and nesting success. The area used by molt migrants and their habitat requirements during molt remain unknown. We suggest that the paucity of predator-safe areas (such as large water bodies) on Bylot Island may be an important factor that drives the geese to molt elsewhere.Key words: breeding effort, greater snow goose, Chen caerulescens atlantica, migration, molt, nesting success, Nunavut, telemetry RÉSUMÉ. Nous décrivons les mouvements migratoires estivaux de la grande oie des neiges (Chen caerulescens atlantica) nichant à l'île Bylot (Nunavut). De 1997 à 2001, 121 femelles munies de radio-émetteurs ont été suivies afin de déterminer la fréquence et le moment de leur départ de la colonie relativement à leur statut reproducteur, leur succès de nidification et la chronologie de la mue. Nous avons trouvé que 90 p. cent (n = 51) des non-reproducteurs (pas de nid trouvé) et 97 p. cent (n = 29) des femelles dont le nid a été détruit ou abandonné avant l'éclosion ont entrepris leur migration avant la mue. Les quelques non-reproducteurs ayant demeuré à l'île Bylot tout l'été ont mué et apparemment entrepris la migration automnale plus tôt que les adultes accompagnés de jeunes. Par contraste, seulement 2 p. cent (n = 41) de femelles ayant niché avec succès ont quitté l'île Bylot pour la mue, après avoir probablement perdu leurs jeunes au début de l'élevage. La migration de mue chez la grande oie des neiges semble donc fortement dépendante du statut reproducteur et du succès de nidification. Nous ne connaissons pas les sites utilisés ni les conditions d'habitat requises pour la mue de ces individus. Nous suggérons que la rareté de refuges contre les prédateurs à l'île Bylot, tels que de grandes étendues d'eau, pourrait être un facteur important qui incite les oies à muer ailleurs.

Movement patterns of Bar-headed Geese Anser indicus during breeding and post-breeding periods at Qinghai Lake, China

“…Previous research on moulting migration showed that the breeding performance of geese species had a strong influence on moulting migration patterns: the majority of successful breeders moulted on or near the breeding grounds, whereas most non-breeders and failed breeders left the breeding grounds to moult elsewhere (Bollinger and Derksen 1996;Reed et al 2003;Luukkonen et al 2008). In our study, it appeared that successful breeders moulted on the breeding grounds.…”

Breeding dispersal in a heterogeneous landscape: the influence of habitat and nesting success in greater snow geese

“…With the help of a helicopter, groups of moulting geese and their young were herded into corral traps by people on foot (see Menu et al 2001 for details). Most of the captured birds were successful nesters with their young of the year, as most nonbreeders and failed-nesters had left the island to moult elsewhere or had regained flight capacity at the time of banding (Reed et al 2003). All birds captured for the first time were fitted with a metal US Fish and Wildlife Service leg band.…”

Canada Geese at the Hanford Site ? Trends in Reproductive Success, Migration Patterns, and Contaminant Concentrations

“…This northward migration was thought to be a molt migration. When geese molt, they lose both flight and tail feathers and are rendered flightless (Reed et al 2003). Birds taking part in a molt migration are generally the nonbreeders or failed breeders.…”