Kevin R. Middel

Bounding the Southern Hudson Bay polar bear subpopulation

Abstract Polar bears (Ursus maritimus) are managed by the 5 nations where they occur (Canada, Greenland/Denmark, Norway, Russia, United States) using discrete subpopulations. In Canada, polar bears are harvested throughout their range, and several subpopulations are managed by more than one jurisdiction; therefore, recent management focused on ensuring sustainable polar bear harvests. Consequently, the subpopulation from which harvested bears are removed and the geographic boundaries of that subpopulation must be correctly identified. However, boundaries of the Southern Hudson Bay (SH) subpopulation have not been verified using satellite radio-telemetry data. Sea ice duration has already declined in Hudson Bay and James Bay, and both the duration and distribution of sea ice are predicted to decline greatly in the next century; therefore, it is important to document current habitat use patterns to assess the potential impacts of climate change. We used a probabilistic approach to describe the utilization distribution for the SH subpopulation based on data from 1997–2003 from 26 adult female bears fitted with satellite collars and assessed whether the currently accepted boundaries represent the population utilization distribution. We conclude that the SH boundaries do reflect the current spatial distribution of adult female bears in this subpopulation. Our analysis provides a benchmark to compare to the future distribution and habitat use of this subpopulation in response to effects of climate change and identifies future research needs to investigate polar bear distribution in James Bay and in the area near the boundary between the SH and Western Hudson Bay management zones.

Does Predation Influence the Seasonal and Diel Timing of Moose Calving in Central Ontario, Canada?

Birth synchrony is well documented among ungulates and is hypothesised to maximize neonate survival, either by minimizing the risk of predation through predator swamping or by synchronising birthing with increased seasonal food availability. We used encapsulated vaginal implant transmitters to locate and capture neonatal moose calves and document the seasonal and diel timing of parturition in two adjacent study areas with different predation pressure in central Ontario, Canada. We tested the hypothesis that predation promotes earlier and more synchronous birth of moose calves. Across both areas, proportionately more births occurred during the afternoon and fewer than expected occurred overnight. Mean date of calving averaged 1.5 days earlier and calving was also more synchronous in the study area with heavier predation pressure, despite average green-up date and peak Normalized Difference Vegetation Index date occurring 2 days later in this study area than in the area receiving lighter predation pressure. We encourage analysis of data on timing of parturition from additional study areas experiencing varying degrees of predation pressure to better clarify the influence of predation in driving seasonal and diel timing of parturition in temperate ungulates.

Re-assessing abundance of Southern Hudson Bay polar bears by aerial survey: effects of climate change at the southern edge of the range

The Southern Hudson Bay polar bear (Ursus maritimus Phipps, 1774) subpopulation is considered stable, but conflicting evidence lends uncertainty to that designation. Capture–recapture studies condu...