Polar bear (Ursus maritimus) Migration from Maternal Dens in Western Hudson Bay

Migration is a common life history strategy among Arctic vertebrates, yet some of its aspects remain poorly described for some species. In February-March, post-parturient polar bears (Ursus maritimus) in western Hudson Bay, Canada, migrate from maternity den sites on land to the sea ice with three- to four-month-old cubs. We investigated this migration using data from 10 adult females fitted with satellite-linked global positioning system collars tracked in 2011 – 16. Directed movement towards the coast began on average on 1 March (range: 31 January to 23 March) and took a mean of 7.8 days to reach the coast. Bears traveled 18 to 100 km from their dens to the coast (mean = 63 km) at a mean rate of 6.7 km/d. Movements were highly directed, with an approximate northeast orientation, but did not follow the shortest path to the coast. Observed migration patterns were broadly similar to those previously documented, although mean departure date from dens was about four days earlier and mean movement rate was only 40% of that from the late 1990s. Given the sensitivity of polar bears to climate change, the phenology of denning may be a meaningful parameter for long-term monitoring.Parmi les vertébrés de l’Arctique, la migration constitue une stratégie de cycle biologique courante et pourtant, pour certaines espèces, certains des aspects de la migration sont toujours mal décrits. En février et en mars, les ours polaires (Ursus maritimus) de post-parturition de l’ouest de la baie d’Hudson, au Canada, migrent depuis leurs aires terrestres de mise bas vers la glace de mer avec leurs oursons de trois à quatre mois. Nous avons étudié cette migration en nous servant des données relatives à dix femelles adultes dotées de colliers satellitaires avec système de localisation GPS, données recueillies de 2011 à 2016. En moyenne, les déplacements dirigés vers la côte commençaient le 1er mars (étendue : du 31 janvier au23 mars) et pour se rendre jusqu’à la côte, il fallait en moyenne 7,8 jours. De leur aire de mise bas jusqu’à la côte, les ours parcouraient de 18 à 100 km (moyenne = 63 km) au taux moyen de 6,7 km/j. Les déplacements étaient fortement dirigés, avec une orientation approximative du nord-est, sans toutefois emprunter le chemin le plus court menant à la côte. Les modèles de migration observés ressemblaient beaucoup aux modèles déjà documentés, quoique la date de départ moyenne des aires de mise bas s’établissait à environ quatre jours plus tôt et que le taux de déplacement moyen ne correspondait qu’à 40 % du taux de la fin des années 1990. Compte tenu de la sensibilité des ours polaires au changement climatique, la phénologie de l’aire de mise bas pourrait constituer un paramètre significatif pour la surveillance à long terme

Abundance and species diversity hotspots of tracked marine predators across the North American Arctic

Aim: Climate change is altering marine ecosystems worldwide and is most pronounced in the Arctic. Economic development is increasing leading to more disturbances and pressures on Arctic wildlife. Identifying areas that support higher levels of predator abundance and biodiversity is important for the implementation of targeted conservation measures across the Arctic. Location: Primarily Canadian Arctic marine waters but also parts of the United States, Greenland and Russia. Methods: We compiled the largest data set of existing telemetry data for marine predators in the North American Arctic consisting of 1,283 individuals from 21 species. Data were arranged into four species groups: (a) cetaceans and pinnipeds, (b) polar bears Ursus maritimus (c) seabirds, and (d) fishes to address the following objectives: (a) to identify abundance hotspots for each species group in the summer–autumn and winter–spring; (b) to identify species diversity hotspots across all species groups and extent of overlap with exclusive economic zones; and (c) to perform a gap analysis that assesses amount of overlap between species diversity hotspots with existing protected areas. Results: Abundance and species diversity hotpots during summer–autumn and winter–spring were identified in Baffin Bay, Davis Strait, Hudson Bay, Hudson Strait, Amundsen Gulf, and the Beaufort, Chukchi and Bering seas both within and across species groups. Abundance and species diversity hotpots occurred within the continental slope in summer–autumn and offshore in areas of moving pack ice in winter–spring. Gap analysis revealed that the current level of conservation protection that overlaps species diversity hotspots is low covering only 5% (77,498 km 2 ) in summer–autumn and 7% (83,202 km 2 ) in winter–spring. Main conclusions: We identified several areas of potential importance for Arctic marine predators that could provide policymakers with a starting point for conservation measures given the multitude of threats facing the Arctic. These results are relevant to multilevel and multinational governance to protect this vulnerable ecosystem in our rapidly changing world

Behavioural ecology of a vulnerable Arctic predator in a dynamic and changing environment

Animal behaviour may represent an early response to variation in habitat suitability. Identifying factors that promote behaviours may be particularly important in areas undergoing environmental change. Recent advances in remote tracking, satellite imagery, and associated methodologies have enabled behavioural research in animals occupying remote environments where direct observation is impractical. Moving habitats (e.g., drifting sea ice) elicit complex behaviours, affect the apparent movement of animals, and are associated with high observation error. In this thesis, I investigated the foraging ecology of polar bears (Ursus maritimus) during the winter. First, I investigated the accuracy of a commonly used model for sea ice motion using dropped GPS collars. I showed that these satellite-based models underestimate the drift speed and have large errors estimating its direction at low speeds. Second, I developed models for remote-tracking data to study behaviours with orientation bias (e.g., relative to wind). Using a popular class of statistical models, hidden Markov models, I developed movement models that allow for error-prone environmental data. I showed that my method effectively recovered behaviour and outperformed other methods when faced with coarse environmental data. Last, I developed a model to correct for sea ice drift and investigated the effect of diurnal, seasonal, and environmental covariates on polar bear behaviour. I identified a peak in diurnal activity later in the day compared to other populations, as well as an increase in activity as the season progressed, which may be indicative of an increase in active foraging. I also identified spatial patterns of distribution with respect to season, ice concentration, and bear age that may reflect high habitat quality in western Hudson Bay and the potential presence of competitive exclusion. My thesis provides a novel assessment of the error present in remotely-sensed sea ice drift models and data that can be used to improve them in the future. In addition, my thesis presents models that can be applied to investigate important, and previously difficult to model, behaviours with orientation bias across taxa. Finally, my thesis expands on our understanding of polar bear foraging ecology with novel insights on its association with the environment.Science, Faculty ofZoology, Department ofGraduat

Characterising menotactic behaviours in movement data using hidden Markov models

Abstract Movement is the primary means by which animals obtain resources and avoid hazards. Most movement exhibits directional bias that is related to environmental features (defined as taxis when biased orientation is voluntary), such as the location of food patches, predators, ocean currents or wind. Numerous behaviours with directional bias can be characterised by maintaining orientation at an angle relative to the environmental stimuli (menotaxis), including navigation relative to sunlight or magnetic fields and energy‐conserving flight across wind. However, new methods are needed to flexibly classify and characterise such directional bias. We propose a biased correlated random walk model that can identify menotactic behaviours by predicting turning angle as a trade‐off between directional persistence and directional bias relative to environmental stimuli without making a priori assumptions about the angle of bias. We apply the model within the framework of a multi‐state hidden Markov model (HMM) and describe methods to remedy information loss associated with coarse environmental data to improve the classification and parameterisation of directional bias. Using simulation studies, we illustrate how our method more accurately classifies behavioural states compared to conventional correlated random walk HMMs that do not incorporate directional bias. We illustrate the application of these methods by identifying cross wind olfactory foraging and drifting behaviour mediated by wind‐driven sea ice drift in polar bears (Ursus maritimus) from movement data collected by satellite telemetry. The extensions we propose can be readily applied to movement data to identify and characterise behaviours with directional bias towards any angle, and open up new avenues to investigate more mechanistic relationships between animal movement and the environment