36 research outputs found
Polar Bear Distribution and Habitat Association Reflect Long-term Changes in Fall Sea Ice Conditions in the Alaskan Beaufort Sea
The polar bear (Ursus maritimus) is considered an indicator species of ecosystem health because of its longevity, life-history requirements, reliance on sea ice (i.e., sea ice obligate), and position in the Arctic food web. Polar bear distribution and habitat association should both be reliable signals for environmental perturbation, as the bears respond behaviorally to changes in sea ice extent, the timing and duration of ice formation, and ablation. Polar bears and sea ice conditions were monitored as part of the annual fall bowhead whale (Balaena mysticetus) aerial survey in the Alaskan Beaufort Sea between 1979 and 2005. Habitats associated with polar bear sightings changed during the study, with fewer bears associated with ice (irrespective of ice type and percent) and more bears associated with land and open water. Large-scale differences were documented for both ice type and percent ice cover, particularly in September. In general, the pattern in September (and to a lesser extent in October) included a reduction in old ice and a concomitant increase in open water. In addition, there was an eastward and landward shift in polar bear sightings. From 1979 to 1987, polar bears were observed primarily on ice along the shelf break near Barrow, whereas from 1997 to 2005, polar bears were observed on barrier islands or along the mainland coast near Kaktovik. The changes in polar bear distribution and habitat association appear to reflect a behavioral response by polar bears to changes in ice (type and percent cover) and in the timing of ice formation and ablation.Lâours polaire (Ursus maritimus) est considĂ©rĂ© comme une espĂšce indicatrice de la santĂ© de lâĂ©cosystĂšme en raison de sa longĂ©vitĂ©, des besoins de son cycle biologique, de sa dĂ©pendance de la glace de mer (câest-Ă -dire la glace de mer obligatoire) et de la position quâil occupe dans le rĂ©seau alimentaire de lâArctique. La rĂ©partition de lâours polaire et son association Ă un habitat devraient tous deux constituer des signaux fiables en matiĂšre de perturbation de lâenvironnement car le comportement des ours varie en fonction des changements caractĂ©risant lâĂ©tendue de glace de mer, la synchronisation et la durĂ©e de la formation de la glace, de mĂȘme que lâablation. Les ours polaires et les conditions de la glace de mer ont fait lâobjet dâune surveillance dans le cadre du levĂ© aĂ©rien annuel de la baleine borĂ©ale (Balaena mysticetus) effectuĂ© Ă lâautomne dans la mer de Beaufort alaskienne entre 1979 et 2005. Au cours de lâĂ©tude, les habitats liĂ©s aux observations dâours polaires ont Ă©voluĂ©, un moins grand nombre dâours Ă©tant associĂ©s Ă la glace (sans Ă©gard au type et au pourcentage de glace) et un plus grand nombre dâours Ă©tant associĂ©s Ă la terre et Ă lâeau libre. Les diffĂ©rences Ă grande Ă©chelle ont Ă©tĂ© rĂ©pertoriĂ©es tant pour le type de glace que pour le pourcentage de couche de glace, particuliĂšrement en septembre. En gĂ©nĂ©ral, la tendance en septembre (et en octobre, dans une moindre mesure) comprenait une rĂ©duction de lâancienne glace de mĂȘme quâune augmentation concomitante dans lâeau libre. De plus, on a enregistrĂ© un dĂ©calage vers lâest et vers lâintĂ©rieur des terres en ce qui a trait aux observations dâours polaires. De 1979 Ă 1987, les ours polaires ont surtout Ă©tĂ© observĂ©s sur la glace le long du rebord continental prĂšs de Barrow, tandis que de 1997 Ă 2005, les ours polaires ont Ă©tĂ© observĂ©s sur les Ăźles-barriĂšres ou le long de la cĂŽte continentale prĂšs de Kaktovik. Les changements caractĂ©risant la rĂ©partition des ours polaires et lâassociation Ă un habitat semblent reflĂ©ter une rĂ©action comportementale des ours polaires vis-Ă -vis des changements relatifs Ă la glace (le type et le pourcentage de la couche) ainsi que de la synchronisation de la formation et de lâablation de la glace
Traditional Knowledge about Polar Bears (Ursus maritimus) in Northwestern Alaska
Polar bears (Ursus maritimus) are an iconic Arctic species, but residents of Arctic coastal communities are among the few who have opportunities to observe their behavior for extended periods of time. Documenting traditional knowledge about polar bears is thus an important research approach, especially in light of recent rapid changes to summer sea ice extent. We interviewed polar bear hunters in seven Alaska Native communities along the coast of the northern Bering Sea and Chukchi Sea. Our study confirmed findings from similar research conducted in the mid-1990s and added information about the responses of polar bears to more recent environmental change. The distribution and local abundance of polar bears have changed over time, though different communities report different patterns. Polar bears arrive from the north later in fall than previously. Despite substantial changes in sea ice and other aspects of polar bear habitat, the animals generally appear to be in good body condition, and cubs continue to be observed regularly. While polar bears continue to feed primarily on seals, they have been observed eating a diverse range of foods, including eggs, greens, fish, berries, and other foods as available. Reduction in harvest levels due to environmental, economic, and social factors is the overriding trend; however, in years when bears are particularly abundant around villages, this pattern is temporarily reversed. Polar bears remain important spiritually and culturally for the indigenous communities of northern and western Alaska.Les ours polaires (Ursus maritimus) constituent une espĂšce iconique de lâArctique, mais les rĂ©sidents des collectivitĂ©s cĂŽtiĂšres de lâArctique figurent parmi les quelques personnes qui ont lâoccasion dâobserver leur comportement pendant des pĂ©riodes prolongĂ©es. Câest pourquoi la consignation des connaissances traditionnelles sur les ours polaires reprĂ©sente un aspect important de la recherche, surtout Ă la lumiĂšre des changements rapides caractĂ©risant lâĂ©tendue de la glace de mer en Ă©tĂ©. Nous avons interviewĂ© des chasseurs dâours polaires de sept collectivitĂ©s autochtones de lâAlaska situĂ©es le long de la cĂŽte nord de la mer de BĂ©ring et de la mer des Tchouktches. Notre Ă©tude a permis de confirmer les observations Ă©manant de travaux de recherche similaires rĂ©alisĂ©s dans le milieu des annĂ©es 1990 ainsi que dâenrichir lâinformation sur la rĂ©action des ours polaires vis-Ă -vis des changements environnementaux plus rĂ©cents. La rĂ©partition et lâabondance locale dâours polaires ont changĂ© au fil du temps, bien que les tendances diffĂšrent dâune collectivitĂ© Ă lâautre. Ă lâautomne, les ours polaires arrivent du Nord plus tard quâavant. MalgrĂ© les importants changements qui caractĂ©risent les glaces de mer et dâautres aspects de lâhabitat de lâours polaire, les animaux semblent gĂ©nĂ©ralement en bon Ă©tat corporel, et lâon continue dâobserver des oursons rĂ©guliĂšrement. MĂȘme si les ours polaires continuent de sâalimenter principalement de phoques, on les a vus en train de manger divers aliments, dont des oeufs, des plantes vertes, du poisson, des petits fruits et dâautre nourriture, selon les disponibilitĂ©s. Les taux de rĂ©colte Ă la baisse en raison de facteurs environnementaux, Ă©conomiques et sociaux constituent la tendance prĂ©pondĂ©rante. Cependant, au cours des annĂ©es pendant lesquelles les ours sont nombreux autour des villages, cette tendance est renversĂ©e temporairement. Par ailleurs, les ours polaires continuent de revĂȘtir une importance spirituelle et culturelle pour les collectivitĂ©s indigĂšnes du nord et de lâouest de lâAlaska
Iñupiaq Knowledge of Polar Bears (Ursus maritimus) in the Southern Beaufort Sea, Alaska
Successful wildlife management depends upon coordination and consultation with local communities. However, much of the research used to inform management is often derived solely from data collected directly from wildlife. Indigenous people living in the Arctic have a close connection to their environment, which provides unique opportunities to observe their environment and the ecology of Arctic species. Further, most northern Arctic communities occur within the range of polar bears (nanuq, Ursus maritimus) and have experienced significant climatic changes. Here, we used semi-structured interviews from 2017 to 2019 to document Iñupiaq knowledge of polar bears observed over four decades in four Alaskan communities in the range of the Southern Beaufort Sea polar bear subpopulation: Wainwright, UtqiaÄĄvik, Nuiqsut, and Kaktovik. All but one of 47 participants described directional and notable changes in sea ice, including earlier ice breakup, later ice return, thinner ice, and less multiyear pack ice. These changes corresponded with observations of bears spending more time on land during the late summer and early fall in recent decadesâobservations consistent with scientific and Indigenous knowledge studies in Alaska, Canada, and Greenland. Participants noted that polar bear and seal body condition and local abundance either varied geographically or exhibited no patterns. However, participants described a recent phenomenon of bears being exhausted and lethargic when arriving on shore in the summer and fall after extensive swims from the pack ice. Further, several participants suggested that maternal denning is occurring more often on land than sea ice. Participants indicated that village and regional governments are increasingly challenged to obtain resources needed to keep their communities safe as polar bears spend more time on land, an issue that is likely to be exacerbated both in this region and elsewhere as sea ice loss continues. La gestion rĂ©ussie de la faune dĂ©pend des efforts de coordination et de consultation avec les collectivitĂ©s locales. Toutefois, il arrive souvent quâune grande partie de la recherche utilisĂ©e pour Ă©clairer la gestion dĂ©rive uniquement des donnĂ©es recueillies directement de la faune. Les peuples autochtones qui vivent dans lâArctique entretiennent des liens Ă©troits avec leur environnement, ce qui crĂ©e des occasions uniques dâobserver lâenvironnement et lâĂ©cologie des espĂšces de lâArctique. Il y a Ă©galement lieu de remarquer que la plupart des collectivitĂ©s du nord de lâArctique se trouvent dans lâaire de rĂ©partition des ours polaires (nanuq, Ursus) et connaissent dâimportants changements climatiques. Dans le cadre de cette Ă©tude, nous nous sommes appuyĂ©s sur des entrevues semi-structurĂ©es rĂ©alisĂ©es entre 2017 et 2019 pour documenter les connaissances des Iñupiaq au sujet des ours polaires dĂ©coulant dâobservations Ă©chelonnĂ©es sur quatre dĂ©cennies dans quatre collectivitĂ©s de lâAlaska situĂ©es dans lâaire de rĂ©partition de la sous-population dâours polaires du sud de la mer de Beaufort : Wainwright, UtqiaÄĄvik, Nuiqsut et Kaktovik. Les 47 participants, sauf un, ont dĂ©crit des changements directionnels et remarquables en ce qui a trait Ă la glace de mer, dont des dĂ©bĂącles plus hĂątives, le retour plus tardif de la glace, de la glace plus mince et moins de banquises pluriannuelles. Ces changements correspondent aux observations dâours qui passent plus de temps sur la terre ferme en fin dâĂ©tĂ© et en dĂ©but dâautomne au cours des derniĂšres dĂ©cennies. Ces observations coĂŻncident avec les Ă©tudes sur les connaissances scientifiques et autochtones rĂ©alisĂ©es en Alaska, au Canada et au Groenland. Les participants ont fait remarquer que la condition corporelle des ours polaires et des phoques ainsi que leur abondance Ă lâĂ©chelle locale variaient dâune rĂ©gion Ă lâautre ou nâaffichaient aucune tendance. Cependant, les participants ont dĂ©crit un phĂ©nomĂšne rĂ©cent selon lequel les ours sont Ă©puisĂ©s et lĂ©thargiques lorsquâils arrivent sur la rive Ă lâĂ©tĂ© et Ă lâautomne, aprĂšs avoir parcouru de longues distances Ă la nage depuis les banquises. Aussi, plusieurs participants ont laissĂ© entendre que les aires de mise bas se retrouvent plus souvent sur la terre ferme que sur la glace de mer. Les participants ont indiquĂ© que le gouvernement des villages et les gouvernements rĂ©gionaux ont de plus en plus de difficultĂ© Ă obtenir les ressources nĂ©cessaires pour assurer la sĂ©curitĂ© de leurs collectivitĂ©s, car les ours polaires passent plus de temps sur la terre ferme, un enjeu qui risque de sâaggraver, tant dans cette rĂ©gion quâailleurs, Ă mesure que la glace de mer continuera de perdre de lâampleur.
Identifying indicators of polar bear population status
Monitoring trends in large mammal populations is a fundamental component of wildlife management and conservation. However, direct estimates of population size and vital rates of large mammals can be logistically challenging and expensive. Indicators that reflect trends in abundance, therefore, can be valuable tools for supporting population monitoring. Polar bears have a relatively simple life history such that a few key variables may be effective indicators for tracking changes in body condition and recruitment that affect abundance. Direct estimates of polar bear abundance are difficult to obtain due to their large home ranges in remote Arctic habitats. Changes in abundance associated with environmental conditions appear to affect polar bears largely via effects on female body condition which influence reproduction and cub survival (i.e., recruitment). Loss of sea ice habitat is further limiting researcher access for population monitoring creating a need for alternative approaches. Here we used relationships established from eight years (2008â2017) of data collected on 439 polar bears in the Chukchi Sea, to transform previously published individual-based relationships with annually available sea ice, atmospheric circulation, and prey body condition variables to predict annual mean body condition and recruitment during 2018â2022. Although annual sample sizes were limited for verifying predicted body condition and recruitment via techniques such as cross-validation, in most cases predicted annual means were closely correlated with observed means for 2008â2017. Summer sea ice and prey body condition remained within or increased relative to levels observed during 2008â2017 and predicted polar bear body condition and recruitment during 2018â2022 were largely within or above observed annual means during 2008â2017. A lack of trend in environmental and ecological variables or polar bear body condition and recruitment metrics during 2008â2022 is suggestive that the Chukchi Sea polar bear population was likely stable during this time. Our results provide support for developing models that predict important population parameters of large mammals based on environmental and ecological indicators. Given that trend information is lacking for 10 of the 19 recognized polar bear populations and is outdated for others, the use of environmental and ecological indicators may be particularly useful for augmenting direct estimates of polar bear vital rates in between periods of data collection. Although demographic assessments for polar bears have primarily focused on correlations with sea ice availability, our study and others highlight that prey health is also an important indicator of polar bear population status
Observed and forecasted changes in land use by polar bears in the Beaufort and Chukchi Seas, 1985â2040
Monitoring changes in the distribution of large carnivores is important for managing human safety and supporting conservation. Throughout much of their range, polar bears (Ursus maritimus) are increasingly using terrestrial habitats in response to Arctic sea ice decline. Their increased presence in coastal areas has implications for bear-human conflict, inter-species interactions, and polar bear health and survival. We examined observed trends in land use over three decades by polar bears in the southern Beaufort Sea (SB) and Chukchi Sea (CS) where bears have traditionally spent most of the year on the sea ice. Using data from 408 adult females fitted with satellite radio-collars, we examined trends in the annual proportion of bears coming onshore (hereafter referred to as âpercent of bearsâ) during the summer for â„ 21 days, arrival and departure dates, duration spent onshore and relationships with sea ice metrics. We then estimated future land use through 2040 by extrapolating trends and by combining observed relationships between land use and sea ice with projections of future sea ice from an ensemble of earth system models. The observed percent of bears summering onshore and their duration onshore was correlated with the percent of open water that occurred within their populationâs range between July and October. As sea ice declined, the percent of bears summering onshore increased from âŒ5â30% in the SB and âŒ10â50% in the CS and duration onshore increased by > 30 days to 60â70 days in both populations. Using a range of greenhouse gas emission scenarios and adjustments for faster than forecasted sea ice loss we estimated that 50â62% of SB and 79â88% of CS bears will spend 90â108 and 110â126 days onshore during summer in the SB and CS, respectively, by 2040. Sea ice projections varied little between greenhouse gas emission scenarios prior to 2040 but diverged thereafter. Observed and forecasted increases in polar bear land occupancy puts more bears in proximity to human activities and settlements for longer durations while extending the lack of access to their primary prey. Because human conflict is one of the primary factors affecting the conservation of large carnivores worldwide, mitigation of bear-human interactions on land will be an increasingly important component of polar bear conservation
Appendix A. Model results examining relationships between the availability of sea ice habitat and measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea.
Model results examining relationships between the availability of sea ice habitat and measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea
Nutritional ecology of elephants in Kibale National Park, Uganda, and its relationship with crop-raiding behaviour
Appendix B. Model results examining trends in measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea between 1983 and 2006.
Model results examining trends in measures of skull width, body length, mass, and condition of polar bears in the southern Beaufort Sea between 1983 and 2006
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