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Article Excerpt
ABSTRACT. We used aerial survey estimates, photographic censuses, and plot counts to examine trends in the size of five black-legged kittiwake (Rissa tridactyla) colonies around Barrow Strait, eastern Nunavut, Canada, between 1972 and 2007. During these three decades, one small colony disappeared, two medium-sized colonies showed no overall trend, and one moderate and one large colony appeared to increase in size. Collectively, the number of kittiwakes breeding in this region may have increased by over 40%. Counts of kittiwakes at some colonies were markedly low in 2003, following two consecutive years of late, extensive sea ice, although overall there was no significant relationship between numbers of kittiwakes attending colonies and sea-ice extent in Barrow Strait and Lancaster Sound. It is not known why kittiwake colonies in High Arctic Canada have apparently increased while those in West Greenland and elsewhere have declined, or what factors influenced these changes.
Key words: black-legged kittiwake, Rissa tridactyla, Arctic, population trend
RESUME. Entre 1972 et 2007, a 1'aide d'estimations effectuees a partir de leves aeriens, de recensements photographiques et de denombrements, nous avons examine les tendances caracterisant la taille de cinq colonies de mouettes tridactyles (Rissa tridactyla) dans les environs du detroit de Barrow, dans Test du Nunavut, au Canada. Pendant ces trois decennies. une petite colonie a disparu, deux colonies de taille moyenne n'ont affiche aucune tendance generate, tandis que la taille d'une colonie de taille moderee ainsi que celle d'une colonie de grande taille ont semble augmenter. Collectivement, le nombre de mouettes tridactyles se reproduisant dans cette region pourrait s'etre accru de plus de 40 pour cent. En 2003, le nombre de mouettes tridactyles de certaines colonies etait nettement bas, ce qui suivait deux annees consecutives de glace de mer tardive et etendue bien que dans l'ensemble, il n'existait pas de relation importante entre le nombre de mouettes tridactyles faisant partie des colonies et l'etendue de la glace de mer dans le detroit de Barrow et le bras de mer de Lancaster. On ne sait pas pourquoi les colonies de mouettes tridactyles de l' Extreme-Arctique sembleraient avoir pris de I'ampleur, tandis que les colonies de 1'ouest du Groenland et d'ailleurs se sont amincies. De plus, on ne connait pas les facteurs qui ont influence ces changements.
Mots cles: mouette tridactyle, Rissa tridactyla, Arctique, tendance caracterisant la population
Traduit pour la revue Arctic par Nicole Giguere.
INTRODUCTION
Seabirds are a ubiquitous feature of the Canadian Arctic marine environment, with millions of birds migrating to this region to breed and feed during the brief Arctic summer (Brown et al., 1975; Mallory and Fontaine, 2004). As seabirds are strong indicators of the health of the marine ecosystem (Cairns, 1987; Montevecchi, 1993), long-term monitoring of seabird populations provides an index of overall changes in the marine food web (e.g., Frederiksen et al., 2004). Indeed, seabird monitoring in Arctic Canada has detected progressive shifts in the relative abundance of small forage fish in response to changing climate, as well as the effects of late, extensive sea ice on marine productivity (Gaston and Hipfner, 1998; Gaston et al., 2003, 2005a).
The black-legged kittiwake (Rissa tridactyla) is a small marine gull with a circumpolar distribution (Baird, 1994) that includes colonies situated in the eastern Canadian Arctic (Brown et al., 1975). Recently concerns have been raised over declining numbers of kittiwakes at colonies around the North Atlantic Ocean, from the United Kingdom (Frederiksen et al., 2004) west to Greenland (Nyeland. 2004). Population reductions have been attributed principally to changes in marine food supplies linked to climate change and effects of commercial fisheries.
Although the kittiwake has been studied elsewhere in its breeding range (Baird, 1994), little research has been conducted on the species in Arctic Canada, despite the fact...
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