Observations of Marine Birds and Mammals Wintering at Polynyas and Ice Edges in the Belcher Islands, Nunavut, Canada H

ARCTIC VOL. 53, N0. 1 (MARCH 2000) P. 61–68 Observations of Marine Birds and Mammals Wintering at Polynyas and Ice Edges in the Belcher Islands, Nunavut, Canada H. GRANT GILCHRIST1 and GREGORY J. ROBERTSON2 (Received 3 February 1999; accepted in revised form 13 October 1999) ABSTRACT. In the Belcher Islands, southeast Hudson Bay, Canada, two types of open water exist during winter: 1) large, wind- driven expanses of water along landfast ice edges and 2) recurring polynyas located between small islands (most < 10 ha and < 15 m deep). In severe winters, only polynyas persist. In March 1998 and 1999, we recorded the species and numbers of birds and marine mammals present at ten polynyas and along four landfast ice edges around the Belcher Islands. To help interpret our observations, we also collected traditional ecological knowledge from local Inuit. Large flocks of common eiders Somateria mollissima (200–12500 birds) were seen along floe edges, and small groups occurred in some polynyas. King eiders S. spectabilis were also observed at several locations, always associated with common eiders. Oldsquaw ducks Clangula hyemalis were common (flocks of 100–500 birds) and occurred primarily at polynyas. Our observations of king eiders represent a significant northern range expansion for this species in Canada during winter. Ravens Corvus corax and snowy owls Nyctea scandiaca were observed along landfast ice edges. Ravens were feeding on the remains of seals killed by Inuit hunters and polar bears Ursus maritimus, and owls apparently hunted sea ducks that were loitering on ice edges at night. We regularly observed bearded seals Erignathus barbatus and ringed seals Phoca hispida at polynyas and floe edges. One beluga whale Delphinapterus leucas was observed by our Inuit guides along a western landfast ice edge, and three walrus Odobenus rosmarus were observed at a floe edge along the southern margin of the Belcher Islands. Clearly, the small recurring polynyas and ice floe edges around the Belcher Islands are important wintering habitat for oldsquaw and common and king eider ducks. Key words: Belcher Islands, eiders, Somateria, oldsquaw, Clangula hyemalis, ice floe edge, polynyas RÉSUMÉ. L’hiver, dans les îles Belcher, au sud-est de la baie d’Hudson (Canada), l’eau libre est présente sous deux formes: 1) de vastes étendues d’eau créées par le vent, longeant la lisière de la glace de rive et 2), des polynies récurrentes situées entre de petites îles (dont la plupart ont une superficie < 10 ha et une profondeur < 15 m). Durant les hivers très rigoureux, seules persistent les polynies. En mars 1998 et 1999, nous avons relevé les espèces et le nombre d’oiseaux et de mammifères marins présents à dix polynies et le long de quatre lisières de glace de rive autour des îles Belcher. Afin de nous aider à interpréter nos observations, nous avons aussi procédé à la collecte de savoir écologique traditionnel auprès des Inuit de la région. On a observé de grandes volées d’eider à duvet Somateria mollissima (200 à 12 500 oiseaux) le long de floes, et on en a trouvé de petits groupes dans quelques polynies. On a également observé à plusieurs endroits la présence de l’eider à tête grise S. spectabilis, toujours en association avec l’eider à duvet. On a souvent retrouvé le harelde kakawi Clangula hyemalis (en volées de 100 à 500 oiseaux), et ce, surtout dans les polynies. Nos relevés de l’eider à tête grise révèlent, pour cette espèce, une expansion notable de son territoire septentrional au Canada durant l’hiver. On a observé le grand corbeau Corvus corax et le harfang des neiges Nyctea scandiaca sur la lisière de la glace de rive. Les corbeaux se nourrissaient des restes de phoques tués par les chasseurs inuit et les ours polaires Ursus maritimus, et il semble que les harfangs chassaient le canard de mer qui s’aventurait la nuit sur la lisière de glace. On a vu de façon régulière des phoques barbus Erignathus barbatus et des phoques annelés Phoca hispida dans les polynies et au bord des floes. Un bélouga Delphinapterus leucas a été aperçu par nos guides inuit le long d’une lisière occidentale de glace de rive, et trois morses Odobenus rosmarus ont été observés au bord d’un floe longeant la rive méridionale des îles Belcher. Il est évident que les petites polynies récurrentes et les bords des floes de glace autour des îles Belcher représentent un habitat d’hivernage majeur pour le harelde kakawi ainsi que l’eider à duvet et l’eider à tête grise. Mots clés: îles Belcher, eiders, Somateria, harelde kakawi, Clangula hyemalis, bord de floe de glace, polynies Traduit pour la revue Arctic par Nésida Loyer. 1 Canadian Wildlife Service, Environment Canada, Suite 301, 5204-50th Avenue, Yellowknife, Northwest Territories X1A 1E2, Canada; [email protected] 2 Canadian Wildlife Service, Environment Canada, 6 Bruce Street, Mount Pearl, Newfoundland A1N 4T3, Canada; [email protected] © The Arctic Institute of North America 62 • H.G. GILCHRIST and G.J. ROBERTSON INTRODUCTION floe edges around the Belcher Islands and quantify for the first time the bird and marine mammal species wintering in Polynyas are areas of open water that occur in polar oceans them. We discuss the dynamic relationship between open- that are otherwise frozen during winter. In effect, they are water areas and the distribution and movements of birds in oases of open water in a sea of ice that enable marine birds relation to changing ice conditions. Finally, we augment and mammals to gain access to food and air. Polynyas that our observations and interpretations by incorporating tra- recur each year are very important ecologically because ditional ecological knowledge of local Inuit residents. many marine wildlife species rely on them as wintering areas (Stirling and Cleator, 1981; Stirling, 1997). Winters during which open-water areas do not occur or METHODS are much reduced may have important effects on the population levels of polar marine birds. For example, in We conducted field work in the Belcher Islands from 2 the Beaufort Sea in April 1964 and 1990, ice movements to 25 March in 1998, and for two periods (3– 12 February and low temperatures caused open-water leads to close. and 16– 30 March) in 1999 (Fig. 1). The timing of trips to These conditions left king eider ducks unable to feed polynyas and ice edges depended on the availability of our during critical periods of low temperature and resulted in Inuit guides and weather conditions. We were able to mass starvation of over 100000 birds (Barry, 1968; Fournier obtain daily assessments of ice conditions and locations of and Hines, 1994). Despite this example, the ecology of sea birds from Inuit hunters. Destinations were chosen on the ducks that use polynyas and recurring leads is poorly basis of this information and prevailing weather. In 1998, known. Indeed, use of open-water areas in the Bering Sea 11 day trips were taken by snowmobile to 11 different and the Sireniki Polynya by wintering spectacled eiders areas of open water. In 1999, field work was expanded to Somateria fischeri has only recently been discovered include snowmobile trips of several days to the southern (Konyukhov et al., 1998; Petersen et al., 1999). region of the Belcher Islands. In 1999, 17 trips were taken Small recurring polynyas form among the Belcher Is- to 12 different areas of open water (8 of these were lands in south Hudson Bay, Canada, because strong tidal polynyas). The areas covered represent 89% (8 of 9) of the currents prevent the formation of ice (Stirling and Cleator, polynyas present in 1998 and 1999. 1981; Nakashima and Murray, 1988). As well, the shifting Upon arriving at a water body, we estimated the num- pack ice driven by wind and the currents of Hudson Bay bers and species of birds. Flocks of sea ducks were counted provide temporary open leads around the Belcher Islands. repeatedly by all members of the crew until we arrived at The polynyas and floe edges of the Belcher Islands and a number within 10% of everyone’s estimate. Occasion- western Quebec are the only permanent areas of open ally, a persistent, low-level ice fog occurred at polynyas, water in southeast Hudson Bay during winter (Smith and and under these conditions, observations were limited. In Rigby, 1981). These areas represent some of the most both years, a description and estimated surface area of the important marine habitats in Hudson Bay during winter. water body were recorded. In 1999, we also recorded water Marine mammals and birds that winter in the region (e.g., depth during each visit, using a depth sounder. The sounder walrus, seals, and common eiders; McDonald et al., 1997; was placed in the water at several locations around the Stirling, 1997) are restricted to these open-water areas and margins of polynyas. Water depth is presented as the mean are apparently vulnerable to mass winterkills because they and standard deviation of these repeated measurements. cannot escape to alternative habitats should the polynyas freeze (Nakashima and Murray, 1988). Traditional Ecological Knowledge Most of the population of the Hudson Bay subspecies of the common eider Somateria mollissima sedentaria win- Studies in the North are logistically challenging and ters in the open-water areas around the Belcher Islands expensive, especially those conducted during winter. To (Snyder, 1941; Todd, 1963; Freeman, 1970a; Nakashima maximize the amount of information we were able to and Murray, 1988). The population of Hudson Bay com- gather, we incorporated traditional ecological knowledge mon eider breeding in the Belcher Islands has declined by (TEK) into our data collection.

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