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A near-total decline in caribou on Prince of Wales, Somerset, and Russell Islands, Canadian Arctic   /   Gunn, A.   Miller, F.L.   Barry, S.J.   Buchan, A.
Arctic, v. 59, no. 1, Mar. 2006, p. 1-13, ill., 1 map
ASTIS record 58542
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The number of caribou (Rangifer tarandus) on Prince of Wales, Somerset, and Russell islands in the south-central Canadian Arctic declined by 98% in 15 years, from an estimated 6048 (16% calves) in 1980 to an estimated 100 (0% calves) in 1995. Those estimates were obtained by systematic aerial surveys that used the same design and methods and comparable survey coverage. We do not have the data needed to determine the rate of decrease between 1980 and 1995 or its possible causes. There is no evidence for large-scale winter mortality in any one year or few consecutive years. A probable explanation for the decline is consequential reductions in long-term survival rates, both of breeding females and of calves in their first year of life, associated with continued caribou harvesting and markedly increased wolf (Canis lupus) predation on the dwindling number of caribou through the 1980s and early 1990s. The delay in detecting the decline and the lack of understanding of its causes will handicap the development of an ecologically sound recovery plan. As previous caribou declines have been followed by recovery, some comfort may be drawn from the likelihood of unaided recovery. However, the number of caribou has declined to the point where recovery will be tenuous and lengthy, at best. Unaided recovery could easily fail to occur, so we should not be complacent, especially as extirpation of these few remaining caribou would remove a distinct genetic group and reduce the biodiversity of caribou on Canada's Arctic Islands.

Le nombre de caribous (Rangifer tarandus) se trouvant sur les îles Prince of Wales, Somerset et Russell, dans le centre-sud de l'Arctique canadien, a chuté de 98 % en 15 ans, passant d'un nombre estimé à 6 048 (dont 16 % étaient des veaux) en 1980 à un nombre estimé à 100 (dont aucun veau) en 1995. Ces estimations ont été obtenues au moyen de relevés aériens systématiques recourant aux mêmes définitions, aux mêmes méthodes et à des aires de relevés comparables. On ne possède pas les données nécessaires pour déterminer le taux de diminution entre 1980 et 1995 ou les causes possibles de cette diminution. Par ailleurs, rien n'indique qu'un taux de mortalité hivernal élevé a été enregistré pendant une année quelconque ou pendant quelques années de suite. Il se peut que le déclin du nombre de caribous enregistré dans les années 1980 et au début des années 1990 soit attribuable aux réductions correspondantes des taux de survie à long terme chez les femelles de reproduction et les veaux pendant leur première année de vie, le tout jumelé au prélèvement continuel des caribous ainsi qu'à la prédation grandement accrue des caribous par les loups (Canis lupus). Le retard à détecter ce déclin et le manque de compréhension de ses causes pourront nuire à l'élaboration d'un plan de récupération solide du point de vue écologique. Puisque les déclins précédents de caribous ont été suivis de récupération, on peut se consoler en se disant qu'il est possible que la récupération se fasse spontanément. Cependant, le nombre de caribous a chuté au point où la récupération sera longue et difficile, même dans le meilleur des cas. Il se peut qu'il n'y ait pas de récupération spontanée et par conséquent, on ne devrait pas se contenter de cette situation, surtout puisque l'extirpation des quelques caribous qui restent pourrait éliminer un groupe génétique distinct et réduire la biodiversité du caribou dans l'archipel Arctique canadien.


Tree-ring dates for the maximum Little Ice Age advance of Kaskawulsh Glacier, St. Elias Mountains, Canada   /   Reyes, A.V.   Luckman, B.H.   Smith, D.J.   Clague, J.J.   Van Dorp, R.D.
Arctic, v. 59, no. 1, Mar. 2006, p. 14-20, ill., 2 maps
ASTIS record 58543
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A dendroglaciological study at Kaskawulsh Glacier provides the first calendar dating of a Little Ice Age glacier advance in the northeast St. Elias Mountains of Yukon Territory. Ring series from white spruce trees, Picea glauca (Moench) Voss, that had been sheared, tilted, and killed by deposition of till at the glacier's terminal moraine were cross-dated with a millennium-length ring-width chronology developed at a site near the south end of Kluane Lake, about 25 km north of the glacier forefield. Six cross-dated samples from two sites at Kaskawulsh Glacier suggest that the north lobe of the glacier reached its greatest Holocene extent in the mid-1750s. Additional limited data suggest that the east lobe may have reached its maximum extent somewhat earlier (ca. 1717). This chronology of Little Ice Age activity of Kaskawulsh Glacier is consistent with well-dated glacier chronologies from adjacent mountain ranges in coastal and interior Alaska. The results also demonstrate the potential to derive calendar dates from subfossil wood in the St. Elias Mountains that hitherto had been dated only with much lower precision, using radiocarbon techniques.

L'étude dendroglaciologique du glacier Kaskawulsh fournit la première datation de calendrier de l'avancée glaciaire du petit âge glaciaire, dans le nord-est des montagnes St. Elias, territoire du Yukon. Les séries de cernes d'épinettes blanches, Picea glauca (Moench) Voss, qui avaient été abattues, inclinées et tuées par le dépôt de till à la moraine terminale du glacier, ont été contre-datées à l'aide d'une chronologie millénaire de largeur des cernes mise au point à un emplacement situé près du côté sud du lac Kluane, à environ 25 km au nord du front du glacier. Six échantillons contre-datés provenant de deux emplacements du glacier Kaskawulsh suggèrent que le lobe nord du glacier a atteint sa plus grande étendue holocène dans le milieu des années 1750. Par ailleurs, certaines données supplémentaires suggèrent que le lobe est pourrait avoir atteint son étendue maximale un peu plus tôt (vers 1717). Cette chronologie de l'activité du petit âge glaciaire du glacier Kaskawulsh coïncide avec les chronologies bien datées des chaînes de montagnes adjacentes, sur la côte et à l'intérieur de l'Alaska. Les résultats démontrent aussi la possibilité d'établir les dates de calendrier à partir de bois subfossile dans les montagnes St. Elias qui avait été daté avec beaucoup moins de précision jusqu'ici à l'aide de techniques de datation au carbone 14.


The nature and significance of polar bear conservation hunting in the Canadian Arctic   /   Freeman, M.M.R.   Wenzel, G.W.
Arctic, v. 59, no. 1, Mar. 2006, p. 21-30
ASTIS record 58544
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The history and current status of polar bear (Ursus maritimus) conservation hunting in the Canadian Arctic, where trophy hunts by non-local hunters have steadily increased in number over the past three decades, have been influenced by local and international factors. Although polar bear hides taken in the subsistence hunt have commercial value, revenues from non-resident trophy hunting provide a much greater economic return to the Inuit. Research suggests that these greater cash returns and the increased local interest by Native hunters in outfitting and guiding do not threaten community cultural values, which continue to emphasize subsistence and the conservation of local wildlife resources. These outcomes suggest that community-based polar bear trophy hunts provide an example of a successful conservation-hunting program that contributes to wildlife management and sustainable economic and community development in the Canadian Arctic.

L'histoire et l'état actuel de la chasse de conservation de l'ours polaire (Ursus maritimus) dans l'Arctique canadien, là où la chasse aux trophées par les chasseurs n'étant pas de la région a augmenté régulièrement au cours des trente dernières années, ont été influencés par des facteurs locaux et internationaux. Bien que les peaux d'ours polaires provenant de la chasse de subsistance aient une valeur commerciale, les revenus puisés de la chasse aux trophées par des personnes étrangères à la région procurent un rendement économique beaucoup plus grand aux Inuits. Des recherches suggèrent que ces rendements monétaires plus élevés et l'intérêt accru à l'échelle locale que portent les chasseurs autochtones aux activités de pourvoirie et de guide ne menacent pas les valeurs culturelles de la collectivité, qui continue à mettre l'accent sur la subsistance et sur la conservation des ressources fauniques locales. Ces résultats suggèrent que les chasses aux trophées d'ours polaires dans la région représentent un exemple de programme de chasse de conservation réussi qui favorise la gestion de la faune de même qu'un développement économique et communautaire durable dans l'Arctique canadien.


Polar bear maternal den habitat in the Arctic National Wildlife Refuge, Alaska   /   Durner, G.M.   Amstrup, S.C.   Ambrosius, K.J.
Arctic, v. 59, no. 1, Mar. 2006, p. 31-36, 2 maps
ASTIS record 58545
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Polar bears (Ursus maritimus) give birth during mid-winter in dens of ice and snow. Denning polar bears subjected to human disturbances may abandon dens before their altricial young can survive the rigors of the Arctic winter. Because the Arctic coastal plain of Alaska is an area of high petroleum potential and contains existing and planned oil field developments, the distribution of polar bear dens on the plain is of interest to land managers. Therefore, as part of a study of denning habitats along the entire Arctic coast of Alaska, we examined high-resolution aerial photographs (n = 1655) of the 7994 km² coastal plain included in the Arctic National Wildlife Refuge (ANWR) and mapped 3621 km of bank habitat suitable for denning by polar bears. Such habitats were distributed uniformly and comprised 0.29% (23.2 km²) of the coastal plain between the Canning River and the Canadian border. Ground-truth sampling suggested that we had correctly identified 91.5% of bank denning habitats on the ANWR coastal plain. Knowledge of the distribution of these habitats will help facilitate informed management of human activities and minimize disruption of polar bears in maternal dens.

Les ours polaires (Ursus maritimus) mettent bas au beau milieu de l'hiver dans des tanières de glace et de neige. Les ours polaires des tanières qui sont la cible de dérangements occasionnés par l'être humain peuvent abandonner leur tanière avant que leurs petits ne soient prêts à survivre les rigueurs de l'hiver de l'Arctique. Puisque la plaine côtière arctique de l'Alaska renferme de grandes possibilités sur le plan pétrolier et comprend des champs pétrolifères mis en valeur ou dont la mise en valeur est planifiée, la répartition des tanières d'ours polaires sur la plaine revêt de l'intérêt chez les gestionnaires des terres. Par conséquent, dans le cadre d'une étude portant sur les habitats des tanières tout le long de la côte arctique de l'Alaska, on a examiné des photographies aériennes de haute résolution (n = 1655) portant sur une superficie de 7994 km2 de la plaine côtière faisant partie de la Réserve faunique nationale de l'Arctique (la Réserve), puis on a cartographié 3621 km d'habitats de berges propices à l'établissement de tanières. Ces habitats étaient répartis de manière uniforme et représentaient 0,29 % (23,2 km2) de la plaine côtière entre la rivière Canning et la frontière canadienne. L'échantillonnage des données de terrain suggérait qu'on avait correctement repéré 91,5 % des habitats de tanières de berges sur la plaine côtière de la Réserve. Le fait de connaître la répartition de ces habitats favorisera une bonne gestion de l'activité humaine et permettra de déranger les our polaires le moins possible dans leurs tanières maternelles.


A review of the occurrence of Pacific salmon (Oncorhynchus spp.) in the Canadian western Arctic   /   Stephenson, S.A.
Arctic, v. 59, no. 1, Mar. 2006, p. 37-46, maps
ASTIS record 58546
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This manuscript summarizes all known captures of Pacific salmon (Oncorhynchus spp.) in the Canadian western Arctic up to the end of 2003. Historic information on Pacific salmon distribution in the Canadian western Arctic is limited, and some older identifications are suspect. It is difficult to determine whether salmon numbers are actually increasing, or whether a recently established program to gather information on Pacific salmon abundance has only made them appear more abundant than historically. However, there is no evidence of newly established populations and overall not enough information to state definitively that salmon are increasing in frequency in the Canadian western Arctic as a direct result of climate change.

Ce manuscrit résume toutes les captures connues de saumon du Pacifique (Oncorhynchus spp.) dans l'ouest de l'Arctique canadien jusqu'à la fin de 2003. Les données historiques portant sur la répartition du saumon du Pacifique sont restreintes, et certaines identifications plus anciennes sont douteuses. Il est difficile de déterminer si le nombre de saumons augmente réellement ou si le programme récemment mis sur pied pour recueillir de l'information sur l'abondance du saumon du Pacifique les fait paraître plus abondants qu'ils ne l'étaient historiquement. Toutefois, il n'existe aucune preuve de populations nouvellement établies et dans l'ensemble, il n'y a pas assez d'information pour affirmer de manière définitive que la fréquence du saumon augmente dans l'ouest de l'Arctique canadien directement en raison du changement climatique.


Long-range transport of information : are Arctic residents getting the message about contaminants?   /   Myers, H.   Furgal, C.
Arctic, v. 59, no. 1, Mar. 2006, p. 47-60, ill.
ASTIS record 58547
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Since contaminants were discovered in Arctic human populations well over two decades ago, northern residents have been receiving information about the nature of such contaminants in the environment and their possible effects on human and wildlife health. The information offered has evolved with attempts to improve its sensitivity and appropriateness and to assure northern peoples that traditional foods are still a healthy choice. A survey conducted in four Nunavut and Labrador communities to evaluate the degree to which residents had been exposed to and comprehended information regarding contaminants in country food found that the information has not been as broadly received as expected. In particular, women of childbearing age-a key population group-do not appear to have understood or to be able to recall messages previously disseminated. We argue the enormous effort put into communication on contaminants is not achieving the desired result: the statements and actions of Arctic people do not reflect the importance of the information passed on through communication programs. Characteristics of risk communication, as well as those of Arctic communities, may be influencing how information is received and interpreted. Much recent dissemination of information about country foods in the Canadian Arctic has emphasized the nutritional value of such foods. Should it become necessary to “nuance” this message in the future, regarding certain species that are being consumed or certain population groups with higher risk of contaminant exposure, it appears that more effective communication modes and messages will need to be developed.

Depuis que des contaminants ont été découverts chez les populations humaines de l'Arctique il y a plus d'une vingtaine d'années de cela, les habitants du Nord ont reçu de l'information sur la nature de ces contaminants dans l'environnement et sur leurs effets possibles sur la santé de l'être humain et de la faune. Les renseignements publiés ont évolué, en ce sens qu'ils sont maintenant plus pertinents et adéquats. Ces renseignements visent aussi à assurer aux peuples du Nord que leur nourriture traditionnelle constitue toujours un choix sain. Grâce à un sondage réalisé dans quatre collectivités du Nunavut et du Labrador dans le but d'évaluer la mesure dans laquelle les habitants ont été en contact avec de l'information concernant les contaminants se trouvant dans la nourriture du terroir et la mesure dans laquelle ils avaient compris cette information, on a pu déterminer que l'information n'avait pas été reçue à aussi grande échelle qu'escompté. En particulier, les femmes en âge de procréer - un segment clé de la population - ne semblent pas avoir compris les messages diffusés ou ne se rappellent pas les avoir vus. On soutient que les efforts énormes qui sont consacrés à la communication sur les contaminants ne donnent pas les résultats voulus : les déclarations et les gestes des gens de l'Arctique ne reflètent pas l'importance de l'information transmise grâce aux programmes de communication. Les caractéristiques de la communication des risques de même que des collectivités de l'Arctique peuvent exercer une influence sur la manière dont l'information est reçue et interprétée. La dissémination plus récente d'information sur la nourriture du terroir de l'Arctique canadien a mis l'accent sur la valeur nutritive de cette nourriture. Advenant qu'il s'avère nécessaire de « nuancer » ce message à l'avenir, en ce qui a trait à certaines espèces qui sont consommées ou à certains segments de la population qui présentent plus de risques d'entrer en contact avec les contaminants, il semblerait que des modes de communication et des messages plus efficaces devront être mis en œuvre.


Co-feeding between Svalbard Rock Ptarmigan (Lagopus muta hyperborea) and Svalbard reindeer (Rangifer tarandus platyrhynchus)   /   Pedersen, Å.Ø   Lier, M.   Routti, H.   Christiansen, H.H.   Fuglei, E.
Arctic, v. 59, no. 1, Mar. 2006, p. 61-64, 2 maps
ASTIS record 58548
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Co-feeding between Svalbard rock ptarmigan (Lagopus muta hyperborea) and Svalbard reindeer (Rangifer tarandus platyrhynchus) on Svalbard, Norway, was observed during our annual point transect survey of territorial Svalbard ptarmigan cocks in two side valleys of Adventdalen and Sassendalen. Both pairs and single hens or cocks used the feeding craters excavated by reindeer in search of food. We suggest that the use of reindeer feeding craters may be important to the Svalbard rock ptarmigan during snow-rich events in winter or after terrestrial ice-crust formation resulting from mild spells and rain-on-snow events. We expect that such co-feeding may be particularly important for saving energy in periods when territorial defence and preparation for the breeding season make high energy demands on ptarmigan of both sexes.

La co-alimentation entre le lagopède alpin de Svalbard (Lagopus mutus hyperboreus) et le renne de Svalbard (Rangifer tarandus platyrhynchus) à Svalbard, en Norvège, a été observée dans le cadre de notre enquête transect annuelle des coqs lagopèdes territoriaux de Svalbard dans deux vallées latérales d'Adventdalen et de Sassendalen. Les poules et les coqs en couples ou célibataires se servaient des fosses de broutage creusées par les rennes à la recherche de nourriture. On suggère que l'utilisation des fosses de broutage des rennes peut revêtir de l'importance pour le lagopède alpin de Svalbard pendant les périodes hivernales riches en neige ou après la formation de glace sur la couche terrestre résultant du temps doux ou de pluie sur la neige. On s'attend à ce que la co-alimentation de ce genre soit particulièrement importante lorsque vient le temps de conserver l'énergie pendant les périodes où la défense du territoire et la préparation pour la saison de reproduction occasionnent de fortes demandes d'énergie chez les lagopèdes des deux sexes.


Oilfield development and Glaucous Gull (Larus hyperboreus) distribution and abundance in central Alaskan Beaufort Sea lagoons, 1970-2001   /   Noel, L.E.   Johnson, S.R.   Gazey, W.J.
Arctic, v. 59, no. 1, Mar. 2006, p. 65-78, ill., maps
ASTIS record 58549
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We evaluated aerial survey data for glaucous gulls (Larus hyperboreus) in central Alaskan Beaufort Sea lagoons near the Prudhoe Bay oilfields during June to September 1978-2001 for trends in numbers of glaucous gulls, associations with human activity, and confounding relationships with environmental variables. Most glaucous gulls were in barrier island and mainland shoreline habitats, and the total number of gulls per survey ranged from 50 to 1600. Seasonal variation in abundance was apparent, with the largest numbers of gulls consistently recorded during September surveys. Ice cover and wave height had a significant negative correlation with the linear density of glaucous gulls (gulls/km). There was no clear trend in abundance of gulls in the lagoons at Prudhoe Bay or obvious interaction with human activity (such as air traffic, boat traffic, or humans on land or water) in the survey area during the period of oilfield development (1978-2001). We compiled glaucous gull nest counts from 1970 to 2001 across barrier islands to evaluate trends in the number of nests and associations with other colonial nesting species. The mean number of active glaucous gull nests increased from 1970-74 (77.6 nests per year) to 1975-85 (154.4 nests per year), but there was no evidence of a difference from 1970-74 to 1987-2001 (153.0 nests per year). However, the change in 1976 from aerial to ground-based nest surveys confounds comparison of the survey periods before this date (1970-74) with those after it (1975-85 and 1987-2001). A strong positive relationship between the number of glaucous gull nests and both common eider and snow goose nests suggests that common environmental variables may be regulating nesting for these species.

On a évalué les données de relevés aériens pour les goélands bourgmestres (Larus hyperboreus) des lagunes de la mer de Beaufort dans le centre de l'Alaska, près des champs pétrolifères de la baie Prudhoe des mois de juin à septembre des années 1978 à 2001 afin de déterminer les tendances caractérisant le nombre de goélands bourgmestres, leurs associations avec l'activité humaine et les relations confondues avec les variables environnementales. La plupart des goélands bourgmestres évoluaient dans des habitats faisant partie de cordons d'îles et de rivages continentaux. Le nombre total de goélands faisant l'objet de chaque relevé variait de 50 à 1600. Du point de vue de l'abondance, les variations saisonnières étaient évidentes, le nombre le plus élevé de goélands étant constamment enregistré en septembre. La couverture de glace et la hauteur des vagues avaient une importante corrélation négative sur la densité linéaire des goélands bourgmestres (goélands/km). Il n'y avait pas de tendance claire en ce qui a trait à l'abondance des goélands sur les lagunes de la baie Prudhoe ou d'interaction évidente avec l'activité humaine (comme la circulation aérienne, la circulation maritime ou les êtres humains évoluant sur la terre ou sur l'eau) dans la zone visée par les relevés pendant la période de mise en valeur des champs pétrolifères (soit de 1978 à 2001). On a compilé le nombre de nids de goélands bourgmestres de 1970 à 2001 à l'échelle du cordon d'îles pour évaluer les tendances caractérisant le nombre de nids et d'associations avec d'autres espèces à nidification qui vivent en colonies. Le nombre moyen de nids de goélands bourgmestres actifs a augmenté de 1970-74 (77.6 nids par année) à 1975-85 (154,4 nids par année). Cependant, il ne semblait pas y avoir de différence entre 1975-85 et 1987-2001 (153,0 nids par année). Cela dit, l'écart enregistré en 1976 entre les relevés aériens et les relevés terrestres à l'égard des nids confond la comparaison des périodes de relevés avant cette date (1970-74) avec celles qui suivent (1975-85 et 1987-2001). Une forte relation positive entre le nombre de nids de goélands bourgmestres et le nombre de nids d'eiders à duvet et d'oies blanches suggère que des variables environnementales communes peuvent régulariser la nidification de ces espèces.


Late Cretaceous plesiosaur teeth from Axel Heiberg Island, Nunavut, Canada   /   Vandermark, D.   Tarduno, J.A.   Brinkman, D.B.
Arctic, v. 59, no. 1, Mar. 2006, p. 79-82, ill., 2 maps
ASTIS record 58550
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We report the discovery of Late Cretaceous plesiosaur teeth from non-marine strata on Axel Heiberg Island in the Canadian High Arctic. In comparison to other plesiosaur teeth, these specimens are most similar to the teeth of elasmosaurs: they have a smooth outer surface and crenulated inner surface, with crenulations that extend nearly to the tip of the tooth. Comparisons with elasmosaurid fossils elsewhere indicate that the Axel Heiberg teeth are from juveniles. The presence of a plesiosaur in non-marine strata on Axel Heiberg Island supports the suggestion that juvenile elasmosaurs frequently inhabited freshwater environments. The temporal distribution of the Axel Heiberg specimens and other occurrences from the High Arctic suggests that elasmosaurids may have expanded their range during a time of extreme climatic warmth.

On signale la découverte de dents de plésiosaure du Crétacé supérieur d'une strate non marine à l'île Axel Heiberg, dans l'Extrême-Arctique canadien. Comparativement aux autres dents de plésiosaures, ces spécimens ressemblent beaucoup aux dents d'elasmosaures : leur surface extérieure est lisse et leur surface intérieure est crénelée, les crénulations s'étendant presque jusqu'à la pointe de la dent. Après avoir comparé ces spécimens aux fossiles d'elasmosaures trouvés ailleurs, on a remarqué que les dents trouvées à Axel Heiberg sont les dents de juvéniles. La présence d'un plésiosaure dans une strate non marine de l'île Axel Heiberg vient étayer la suggestion selon laquelle des elasmosaures juvéniles évoluaient souvent dans les milieux dulçaquicoles. La répartition temporelle des spécimens d'Axel Heiberg et d'autres occurrences de l'Extrême-Arctique laissent suggérer que les elasmosaures auraient pu étendre leur parcours au cours d'une période d'extrême chaleur climatique.


Offshore distances of bowhead whales (Balaena mysticetus) observed during fall in the Beaufort Sea, 1982-2000 : an alternative interpretation   /   Treacy, S.D.   Gleason, J.S.   Cowles, C.J.
Arctic, v. 59, no. 1, Mar. 2006, p. 83-90, maps
ASTIS record 58551
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Nineteen years (1982-2000) of sighting data from fall aerial surveys of bowhead whales (Balaena mysticetus) in the Alaskan Beaufort Sea were analyzed to determine how patterns in the distribution of migrating bowhead whales relate to annual sea-ice conditions. Transect sighting rate (transect sightings/km) indicated (ANOVA; F2,980 = 143.84, p < 0.0001) that bowhead whales occurred farther offshore in years of heavy ice conditions (73.4 km, 95% CL: 67.2-79.6 km) than in years of moderate (49.3 km, 95% CL: 44.8-53.84 km), or light (31.2 km, 95% CL: 30.0-32.4 km) ice conditions. The most plausible explanation for the observed pattern in bowhead whale distribution is that in years of heavy ice conditions (annual pack ice; 1983, 1988, 1991), the developing landfast ice limits availability of shallow nearshore habitat, thus necessitating use of leads and ice openings in deeper water. We acknowledge that factors such as bathymetry, ocean currents, transport, and food availability may also interact to influence autumn distribution of bowhead whales. In heavy ice years, however, these factors likely exert less influence on bowhead whale distribution than in years with light to moderate ice conditions.

Les données automnales prélevées à partir de relevés aériens pendant 19 années chez les baleines boréales (1982-2000) (Balaena mysticetus) de la mer de Beaufort alaskienne ont été analysées dans le but de déterminer comment les tendances caractérisant la répartition des baleines boréales en migration se rapportent à l'état annuel des glaces et de la mer. Le taux de repérage transect (repérage transect/km) a indiqué (ANOVA; F2, 980 = 143.84, p < 0,0001) que les baleines boréales se trouvaient plus loin au large pendant les années où il y avait beaucoup de glace (73,4 km, 95 % CL: 67,2-79,6 km) que pendant les années où la glace était modérée (49,3 km, 95 % CL: 44,8-53.84 km) ou légère (31,2 km, 95 % CL: 30,0-32,4 km). L'explication la plus plausible à la source de la tendance qui a été observée en matière de répartition des baleines boréales, c'est que pendant les années où il y a beaucoup de glace (banquise; 1983, 1988, 1991), la glace de rive en formation limite la disponibilité d'habitats de faible profondeur à proximité du littoral, ce qui nécessite l'utilisation de chenaux et d'ouvertures dans la glace en eau plus profonde. On reconnaît que des facteurs comme la bathymétrie, les courants océaniques, le transport et la disponibilité de la nourriture peuvent également entrer en interaction au point d'exercer une influence sur la répartition automnale des baleines boréales. Cependant, pendant les années où il y a beaucoup de glace, ces facteurs sont susceptibles d'exercer moins d'influence sur la répartition des baleines boréales que pendant les années où la couverture de glace varie de légère à moyenne.


Frank A. Pitelka (1916-2003)   /   Batzli, G.O.
Arctic, v. 59, no. 1, Mar. 2006, p. 91-93, ill.
ASTIS record 58552
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Although the biological lore of Arctic Alaska had many early contributors, our biological knowledge of the North Slope grew exponentially after 1947, when the U.S. Naval Arctic Research Laboratory (NARL) was established at a navy base just north of Barrow, Alaska. Among the many distinguished scientists who have since studied the biota of the North Slope of Alaska, none has contributed more to our understanding of the distribution, abundance, and behavior of terrestrial mammals and birds than Frank A. Pitelka. During the 1950s, 60s, and 70s, he not only led major research projects of his own but also recruited a substantial coterie of graduate students and post-doctoral fellows to work in Arctic tundra. Born on 27 March 1916 and raised in Berwyn, Illinois, a suburb of Chicago, Pitelka came from a family of Czech immigrants and spoke Czech at every opportunity throughout his life. His development as a biologist began in elementary school, when he began to take bird walks with his teacher. As his interests in birds gathered momentum during high school, he found a mentor in Mrs. Nellie J. Baroody, who was active in the Illinois Audubon Society. Upon graduation he wanted to go to university to begin his formal training as a biologist, but the Great Depression and the need to earn money stood in his way. While employed at General Electric, he managed to take courses at a local two-year college (Morton Junior College in Cicero, Illinois) and finally entered the University of Illinois at Urbana-Champaign in 1937, at age 21. Because he was an older, dedicated student who had already begun publishing his observations on birds, he soon caught the attention of two eminent ecologists then at Illinois, Victor E. Shelford and S. Charles Kendeigh. He became Kendeigh's research assistant and continued to publish papers. As a result of these activities, he shared an office with graduate students, one of whom was no less than Eugene Odum, a PhD student of Kendeigh at that time. After graduation in 1939 (summa cum laude with a double major in zoology and chemistry), Pitelka arranged to start a doctoral program at the University of California at Berkeley with another prominent ecologist, Joseph Grinnell, the founding director of the Museum of Vertebrate Zoology (MVZ). Unfortunately, Grinnell unexpectedly died of a heart attack, so Pitelka needed to find another sponsor, and he became the student of Alden Miller, a prominent ornithologist and the new director of MVZ. Under Miller's guidance, Pitelka's interests took a turn toward evolution and systematics. ... In 1951, at the invitation of Ira Wiggins, the director of NARL, Pitelka went to Barrow to begin research on the myriads of breeding birds on the nearby coastal tundra, and he continued that research for about 30 years. As luck would have it, brown lemmings were also fairly abundant in 1952 and built to peak densities in 1953, so he could observe firsthand the dramatic events at snowmelt during a lemming high. Lemmings scurried everywhere, the vegetation appeared devastated, and predatory birds and mammals feasted on the lemmings (for a detailed description of these events, see Thompson, 1955). This experience convinced Pitelka that lemmings played a crucial role in the dynamics of the tundra ecosystem as a whole, and he began to envision an expanded research program. ... Pitelka followed up his interest in the interactions of components of tundra ecosystems in two ways. First, he and his students (W.J. Maher and S.F. MacLean, Jr.) documented the dramatic responses of avian and mammalian predators to fluctuating lemming populations and studied the potential impact of predation on those populations. Second, he recruited Arnold Schultz, a plant ecologist and colleague from Berkeley, to begin a study of lemming-plant-soil interactions. That collaboration resulted in the well-known Nutrient Recovery Hypothesis (Pitelka, 1964; Schultz, 1964), which explained how the high lemming populations reduced plant cover and the insulation provided by dead vegetation, thereby increasing the depth of thaw and diluting the soil nutrient pool. The resultant delay in recovery of plant quality and production could account for the cyclic population dynamics of lemmings and their predators in the coastal tundra on the North Slope. Although not all aspects of this hypothesis have been confirmed, it has stimulated research on the role of changes in food quality and quantity in the population dynamics of arvicoline rodents. ... During the 1950s-70s, Pitelka, his graduate students, and his post-doctoral associates ... also produced a spate of important publications on Arctic birds. These included studies on the ecology of predatory birds (jaegers and owls); on the distribution, taxonomy, social behavior, and ecology of shorebirds; and on the demography and food requirements of the Lapland longspur, a fringillid common near Barrow. Many observations also were made on the avifauna in general (Pitelka, 1974). Finally, because of his interests in food availability and the impact of weather, Pitelka even supported studies of soil arthropods (the main food of many breeding shorebirds) and variability in summer temperature. ... In addition to his activities in research and teaching, Pitelka served in a variety of administrative positions at the University of California at Berkeley, as an editor of several professional journals, and on advisory panels to national and international agencies. Most relevant for this profile, he also served as the first director of the Tundra Biome, a large ecosystem research program in the early 1970s that was supported by the National Science Foundation as a U.S. contribution to the International Biological Program. As a result of all this activity and as a tribute to his achievements, Pitelka received numerous professional awards, including the William Brewster Award from the American Ornithologists Union (1980), the Mercer Award (1953 - mentioned ab ove) and the Eminent Ecologist Award (1992) from the Ecological Society of America, the Distinguished Teaching Award from the University of California at Berkeley (1984), the LAS Alumni Achievement Award from the University of Illinois (1993), and an honorary doctoral degree from Masaryk University in Brno, Czech Republic (1997). Finally, he was an elected fellow of the Arctic Institute of North America, the American Ornithologist's Union, the American Association for the Advancement of Science, the Animal Behavior Society, and the California Academy of Sciences, and an honorary member of the Cooper Ornithological Society. Surely these honors confirm the importance of Pitelka's contributions to biology in general and to Arctic biology in particular.


Foraging ecology and population dynamics of collared pikas in southwestern Yukon   /   Morrison, S.F.
Arctic, v. 59, no. 1, Mar. 2006, p. 104-106, ill.
ASTIS record 58553
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The foraging decisions made by herbivores influence population dynamics through their effects on energy gain, energy expenditure, and ultimately, survival (McNamara and Houston, 1997). In turn, foraging by herbivores may influence the amount of vegetation available for the future. Therefore, herbivores and vegetation often are coupled in a strong reciprocal relationship: the abundance of one affects the abundance of the other through time (e.g., Caughley, 1976). This interaction is particularly important for herbivores living in seasonal environments where food abundance and quality vary dramatically between growing and winter seasons. Herbivores must adapt their foraging behaviour to contend with these changes and survive until the following growing season (Owen-Smith, 2002). In addition to seasonal effects, daily foraging decisions are constrained by a number of other factors, which may be classified as either internal (such as energetic or nutritional needs), or external (such as predation risk or interspecific interactions). These constraints limit the availability of food items to the herbivore and explain why most species exhibit some degree of diet selectivity. Most species, therefore, must balance trade-offs associated with these constraints such as obtaining enough food while minimizing predation risk (Lima and Dill, 1990), or decisions about selecting species with differing degrees of nutritional value (Stephens and Krebs, 1986). I am using a combination of descriptive and experimental methodologies, combined with modelling techniques, to increase our understanding of plant-herbivore interactions and their influence on herbivore population dynamics, using the collared pika (Ochotona collaris) as a model species. Pikas are small (~160 g) lagomorphs that live in alpine talus slopes. Pikas are asocial and each individual collects vegetation for two distinct diets: a summer diet that is consumed immediately, and a winter diet that is stored in haypiles under boulders (Millar and Zwickel, 1972; Conner, 1983). Because of predation risk, pikas rarely venture more than 10 m from talus into meadows to collect vegetation (Holmes, 1991), and this behaviour creates a strong gradient of grazing pressure, with most foraging activity occurring within 3 m of talus (Huntly, 1987; McIntire and Hik, 2005). Insatiable hoarders of vegetation (McKechnie et al., 1994), pikas provide an opportunity to test experimentally hypotheses regarding diet selection as a function of various constraints. Since 1995, most individuals (> 95%) within the study area have been captured, weighed, sexed, and marked with uniquely coloured ear tags. This detailed, long-term demographic dataset will provide context for this study and a means of validating population models. The objectives for this project are 1) to determine how collared pikas make foraging decisions with respect to predation risk and forage quality, 2) to incorporate these constraints into a plant-herbivore modelling approach to determine their effects on population dynamics, and 3) to compare the plant-herbivore model to spatial demographic models of population dynamics. The project is being conducted in a 4 km² alpine valley near Kluane Lake in the southwestern Yukon. The valley is an alpine meadow interspersed with talus slopes. Collared pikas, hoary marmots (Marmota caligata), and arctic ground squirrels (Spermophilus parryii) are the dominant herbivores in the valley and have been studied there since 1995 (Hik et al., 2001). Predation on pikas within the valley is relatively low (Franken, 2002), suggesting that pika populations are more influenced by food resources and environmental conditions than by predation, a relationship similar to that observed for marmots in this study area (Karels and Hik, 2003). ...


Potential sources of monomethyl mercury in Arctic and Subarctic seawater   /   Kirk, J.L.
Arctic, v. 59, no. 1, Mar. 2006, p. 108-111, ill.
ASTIS record 58554
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Mercury (Hg) is a heavy metal that exists in many different forms in the environment. One of these forms, monomethyl mercury (MMHg), is a strong vertebrate neurotoxin that bioaccumulates through food webs. In some Canadian Arctic marine mammals, MMHg has increased to levels that may be toxic to northern peoples who consume these species as traditional foods (INAC, 2003). Unfortunately, it is difficult to determine the sources of Hg contamination in northern food webs because the cycling of Hg is complex and not well characterized in Arctic marine ecosystems. Mercury may enter the Arctic via a number of pathways (see general schematic). For example, gaseous Hg(0) released by industrial processes such as coal combustion and waste incineration is relatively stable in the atmosphere and can be transported to the Arctic on air currents (Shroeder and Munthe, 1998). Gaseous Hg(0) can flux into or out of waterbodies, such as lakes and oceans, depending on where concentrations of Hg(0) are higher. Inorganic Hg(II) and MMHg may also enter Arctic marine ecosystems in precipitation, river inflow, and glacial melt, as well as via ocean currents. ... We studied atmospheric Hg depletion events over western Hudson Bay in spring 2004 by continuously monitoring atmospheric concentrations of gaseous Hg(0), RGM, and pHg while simultaneously measuring the deposition of Hg(II) into snowpacks. The results of this study, which are currently being prepared for publication, indicated that although a large amount of Hg was deposited into snowpacks during Hg depletion events, most of it was photo-reduced to gaseous Hg(0) and remitted to the atmosphere soon after depletion events ceased, and well before snowmelt entered the marine ecosystem at ice-out. We therefore hypothesize that the Hg transmitted to Arctic marine food webs must have other sources, and we have started to examine Hg cycling in polar oceans themselves. ... Methylated Hg species, including MMHg and dimethyl Hg(DMHg), have been found in sub-thermocline North Atlantic waters, where they are probably produced by marine bacteria (Mason et al., 1998). In regions of deepwater upwelling or winter thermocline mixing, DMHg can be brought to the surface and subsequently lost to the atmosphere by gas exchange. It is likely that atmospheric DMHg is rapidly photolyzed to MMHg (Cl + CH3HgCH3 leads to CH3HgCl + CH3) (Niki et al., 1983), making the ocean a potential source of atmospheric MMHg. We hypothesize that MMHg found in Arctic snowpacks originates from DMHg fluxing through polynyas and leads in the sea ice during the winter. Furthermore, we hypothesize that active methylation of Hg(II) in polar oceans produces not only DMHg, but also large quantities of MMHg. I began testing these hypotheses from August to October 2005, while on board the icebreaker CCGS Amundsen as part of ArcticNet, a Network of Centres of Excellence of Canada developed to study the impact of climate change on Canadian Arctic coastal areas. Seawater was sampled at many sites in the High Arctic and Hudson Bay for concentrations of DMHg and MMHg, as well as for total Hg (THg; or all forms of Hg in a sample), and dissolved gaseous Hg(0). To delineate regions of production or loss (or both) of different Hg species within the water column, seawater was sampled from different ocean depths (surface, middle, and bottom). ... This sampling design allows us to examine the spatial distribution of the four species of Hg in Arctic and Subarctic seawaters and to gain an understanding of the biogeochemical cycling of Hg at these sites. ... At present, I have only preliminary DMHg results from the CCGS Amundsen icebreaker cruise, as the other samples are currently being analyzed. Seawater samples collected at numerous sites in the North Water polynya, Northwest Passage, and Hudson Bay had very high concentrations of DMHg. Concentrations were the highest (often 100-200 pg/L) in samples collected at bottom depths (below ~ 100 m), indicating that DMHg is being produced in deep Arctic seawaters. These results suggest that active methylation of Hg(II) occurs in polar waters, and we therefore expect to see high concentrations of MMHg in many of the samples collected on the cruise. In surface water samples at all sites, concentrations of DMHg were low (often just above detection limits), likely because DMHg is photodegraded to MMHg by solar radiation. Using our measured concentrations of DMHg and piston velocities supplied by others on the CCGS Amundsen cruise, we will calculate surface fluxes of DMHg to determine how much atmospheric MMHg is potentially produced in oceans. We will then be able to determine the relative importance of MMHg originating from DMHg and MMHg directly produced in the water column or sediments of polar oceans. We will also calculate gaseous Hg(0) fluxes to determine whether polar oceans are sinks or sources of atmospheric gaseous Hg(0). We hope that the research described here, in addition to providing new information about the biogeochemical cycling of Hg in the Arctic, will help us to understand the sources of MMHg found in marine mammals that northern people use for food.


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