Gosling body mass can affect first year survival, recruitment, adult body size, and future fecundity of geese, and can serve as an indicator of forage availability and quality on brood-rearing areas. From 2012-2014 we measured body mass of 76 black brant (Branta bernicla nigricans) and 268 lesser snow goose (Chen caerulescens caerulescens) goslings of known age on the Colville River Delta (CRD) of northern Alaska to determine if there was evidence of density-dependent declines in gosling growth following recent population increases of those species and sympatric greater white-fronted geese (Anser albifrons frontalis). We contrasted contemporary body mass of brant goslings and forage biomass in brood-rearing habitats that were shared by all species, with measures obtained on, and near the CRD in the 1990s, prior to the establishment of snow goose nesting colonies in the area. Body mass of brant goslings recaptured between 25 and 32 days of age had not changed over the past 2 decades, despite an influx of snow geese, and increases in populations of brant and white-fronted geese. At 30 days of age, body mass of brant goslings on the CRD was 100-400 g heavier than for brant goslings of the same age on the Yukon-Kuskokwim Delta (YKD), Alaska. Contemporary biomass of grazed Carex subspathacea on CRD brood-rearing areas was comparable to the 1990s and was 2-4 times greater than for the same plant community on the YKD. Historical data on growth of snow goose goslings were not available for the CRD. However, average body mass of 34-day-old snow goose goslings was >230 g heavier than for conspecifics of the same age in the Hudson Bay region. We conclude that the establishment of nesting snow geese on the CRD has not negatively affected brant gosling growth, and that recent population increases of all species have likely not been constrained by forage availability on brood-rearing areas. Barring demographic changes elsewhere in their annual cycles, we predict that goose populations will continue to increase in northern Alaska. However, snow geese are increasing more rapidly than brant in the region. Because the black brant population has periodically been below conservation objectives, the effects of the increasing number of snow geese on forage biomass and growth of brant goslings in northern Alaska should be monitored. Ó 2017 The Wildlife Society.

ABSTRACT. The breeding biology of Steller's eiders (Polysticta stelleri) near Barrow, Alaska, was studied from 1991 to 1999. The number of nests found per year ranged from 0 to 78. Mean clutch size was 5.4 (SD = 1.6, n = 51), incubation period was 24 days, and Mayfield nest success ranged from 0 to 35%. Egg survival was 24% overall (n = 451). Most nests were found on the rims of low-centered polygons near ponds with emergent vegetation. Marked broods remained within 700 m of their nest sites, and duckling survival was low. Steller's eiders nested in five of the nine years studied, corresponding with years of high lemming density and nesting pomarine jaegers (Stercorarius pomarinus) and snowy owls (Bubo scandiacus). Steller's eiders may choose to nest only in years with abundant lemmings for two reasons: first, abundant lemmings provide an alternative prey source for foxes and other predators of eiders; second, jaegers and owls defending their own nests may inadvertently provide protection to eiders nesting nearby.Key words: Alaska, Steller's eider, Polysticta stelleri, nesting success, habitat selection, nesting associations, periodic nonbreeding RÉSUMÉ. De 1991 à 1999, on a étudié la biologie de reproduction de l'eider de Steller (Polysticta stelleri) près de Barrow, en Alaska. Le nombre de nids trouvés annuellement allait de 0 à 78. La taille moyenne de la couvée était de 5,4 (écart type = 1,6, n = 51), la période d'incubation était de 24 jours et le succès de la couvée calculé selon la méthode de Mayfield allait de 0 à 35 %. La survie des oeufs était dans l'ensemble de 24 % (n = 451). La plupart des nids étaient situés sur le bord de polygones concaves près d'étangs avec une végétation émergente. La progéniture marquée restait dans les 700 m du site du nid, et la survie des canetons était faible. L'eider de Steller a niché cinq ans sur les neuf de l'étude, soit ceux correspondant aux années où il y avait une forte densité de lemmings, ainsi que de nids de labbes pomarins (Stercorarius pomarinus) et de harfangs des neiges (Bubo scandiacus). Il se pourrait que l'eider de Steller choisisse de ne se reproduire que durant les années d'abondance de lemmings pour deux raisons: la première, c'est qu'une abondance de lemmings offre une source alternative de proies pour les renards et d'autres prédateurs de l'eider; la deuxième, c'est que les labbes pomarins et les harfangs qui défendent leurs propres nids pourraient, involontairement, offrir une protection aux eiders qui nichent à proximité.Mots clés: Alaska, eider de Steller, Polysticta stelleri, réussite de la couvée, sélection de l'habitat, association de nidification, nonreproduction périodique Traduit pour la revue

ABSTRACT. Although shifts in the distribution of red foxes into areas previously dominated by Arctic foxes have been documented over wide areas of the circumpolar North, no such documentation exists yet for the Alaskan Arctic. Fox research in the greater Prudhoe Bay area from the 1970s through the early 1990s focused primarily on Arctic foxes in relation to oil development because red foxes were uncommon. A monitoring program in 2005 -12 included annual surveys of 31 -48 fox dens within 2 km of the road system. In 2005, 2006, and 2008, Arctic fox dens outnumbered those of red foxes, but from 2010 onward, the reverse was true. There is greater distance between natal dens of Arctic foxes and those of red foxes than between natal dens within each species, suggesting that Arctic foxes avoid red fox denning territories. Of dens in our study that were used by Arctic foxes prior to 2005, 50% have since been occupied by red foxes. Red foxes displaced Arctic foxes from dens closest to oil field camps, pads, and other facilities, and preyed on their pups. Access to anthropogenic food sources probably supports red foxes in the area. Predictions from climate change studies indicate the displacement of Arctic foxes by red foxes will continue in the Alaskan Arctic, although the change may be slower away from areas of human occupation and anthropogenic foods.Key words: Arctic fox, red fox, den occupancy, interference competition, anthropogenic food sources, climate change RÉSUMÉ. Malgré que des changements sur le plan de la répartition du renard roux dans des régions qui étaient auparavant dominées par le renard arctique aient été répertoriés dans une grande partie du Nord circumpolaire, ce n'est pas encore le cas de l'Arctique alaskien. L'étude des renards de la grande région de la baie Prudhoe, des années 1970 jusqu'au début des années 1990, portait principalement sur le renard arctique dans le cadre de la mise en valeur du pétrole, car le renard roux n'était pas courant à ce moment-là. Un programme de surveillance mené à bien de 2005 à 2012 a notamment pris la forme de dénombrements annuels de 31 à 48 tanières de renards dans un rayon de deux kilomètres du réseau routier. En 2005, en 2006 et en 2008, le nombre de tanières de renards arctiques dépassait le nombre de tanières de renards roux, mais à partir de 2010, c'était l'inverse. La distance qui sépare les tanières de mise bas des renards arctiques de celles des renards roux est plus grande que la distance qui sépare les tanières de mise bas au sein de chacune des espèces, ce qui laisse entendre que le renard arctique évite les territoires de mise bas du renard roux. Parmi les tanières visées par notre étude qui étaient utilisées par les renards arctiques avant 2005, 50 % d'entre elles sont depuis occupées par des renards roux. Les renards roux ont supplanté les renards arctiques qui occupaient les tanières situées plus près des campements de champs pétrolifères, des zones tampons et d'autres installations, et ils ont attaqué leurs petits. L'accès aux sources alimentaires...

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Abstract. Annual spring aerial surveys were initiated in 1992, and repeated in 1993, 1994, 1997, 1998, 2000, 2001, 2002, 2003, 2004 and 2005 to monitor the population status of and habitat use by Steller's eiders (Polysticta stelleri) migrating northward in southwestern Alaska. Since the timing of migration varies, two to three replicate shoreline surveys were conducted each spring through 1997, to increase the probability of encountering the entire population of eiders as they transited the survey area en route to their arctic breeding grounds. Fiscal constraints and inclement weather in subsequent years resulted in successful completion of only one survey per year, the timing of which was carefully scheduled using satellite sea ice imagery and other available data. The 2005 survey was conducted 4/2 to 4/8. We made visual estimates of Steller's eiders and all other identifiable water birds and marine mammals. The design consisted of a census of shorelines, embayments and shoals where Steller's eiders and other seaducks were known to congregate during migration. To enhance consistency, most flock estimates of Steller's eiders were made by the pilot/port side observer (Larned), who has fulfilled that function for each survey since the project's inception. In each year where multiple surveys were completed, the highest Steller's eider count was used as that year's population estimate. Annual Steller's eider raw counts are