Spatial and Temporal Habitat Use of an Asian Elephant in Sumatra

Increasingly, habitat fragmentation caused by agricultural and human development has forced Sumatran elephants into relatively small areas, but there is little information on how elephants use these areas and thus, how habitats can be managed to sustain elephants in the future. Using a Global Positioning System (GPS) collar and a land cover map developed from TM imagery, we identified the habitats used by a wild adult female elephant (Elephas maximus sumatranus) in the Seblat Elephant Conservation Center, Bengkulu Province, Sumatra during 2007–2008. The marked elephant (and presumably her 40–60 herd mates) used a home range that contained more than expected medium canopy and open canopy land cover. Further, within the home range, closed canopy forests were used more during the day than at night. When elephants were in closed canopy forests they were most often near the forest edge vs. in the forest interior. Effective elephant conservation strategies in Sumatra need to focus on forest restoration of cleared areas and providing a forest matrix that includes various canopy types

Spatial Ecology of Black Bears (Ursus americanus) in Newfoundland, Canada

Although black bears (Ursus americanus) are among the most studied mammals in the world, little is known about their ecology in Newfoundland, Canada. I investigated the spatial ecology of black bears on the island, focusing on unusual movements during the denning period and their role as caribou (Rangifer tarandus) calf predators. I investigated the influence of climatic conditions (rainfall) and anthropogenic disturbance on the rate of den abandonment for black bears in Newfoundland, a population with an unusually high rate of abandonment given its northern latitude. I found no evidence that rainfall or anthropogenic disturbance played a role in den abandonment. My results may provide preliminary background rates of den abandonment for a northern and relatively remote ecosystem, with which to assess future change. I examined black bear predation of caribou neonates using long-term mortality and location data from 21 bears and 308 caribou. I investigated the influence of landscape features on calf vulnerability, evaluated if bears actively hunted calves, and assessed the impact of changes in the abundance and vulnerability of calves on the foraging strategy of bears. I found that landscape heterogeneity influenced calf vulnerability, and that bears selected areas where they were most likely to kill or encounter calves. Initially, daily kill rates varied with calf abundance in a type-I functional response, but, as calf vulnerability declined, kill rates dissociated from abundance. Bears adjusted their foraging strategy based upon the efficiency with which they could catch calves, highlighting the influence of predation phenology on predator space use. Most bear predation of calves occurs when caribou are aggregated on calving grounds. Some bears visit calving grounds (visitors), and thus have opportunities to prey on calves, whereas others do not (non-visitors). I evaluated differences in resource selection patterns between 4 visitor and 2 non-visitor populations (56 bears). Visitors showed stronger selection than non-visitors for local-scale landscape features associated with increased mortality risk for calves, but selection patterns were not entirely consistent among visitors and non-visitors. At the landscape-scale, most visitors displaying stronger selection than non-visitors for open landscape features associated with an increased probability of encountering caribou calves

Black Bear Movements and Caribou Calf Predation in Newfoundland

The population trajectory of woodland caribou (Rangifer tarandus caribou) in Newfoundland is currently determined by low calf survival due to high predation rates during the first 6-8 weeks after parturition. Most caribou in Newfoundland congregate and give birth in open calving grounds; consequently, in order to investigate predator-prey interactions, design research, and develop mitigation strategies, the geographic extent of the caribou calving grounds must be properly identified. We used VHF telemetry locations of caribou calves, collected from 2003-2010, to determine the spatial and temporal extent of caribou calving grounds in three study areas in Newfoundland. We put GPS collars on 47 black bears (Ursus americanus) in 3 caribou ranges where bears are having a significant impact on caribou recruitment by preying on calves during the calving season. Bear movements were greatest during the calving season, potentially increasing encounters with calves. Some bears migrated to the calving grounds just prior to caribou parturition, indicating deliberate broad-scale selection of areas of high calf density. Bears displayed interannual fidelity to calving ground usage patterns during the calving season, with some bears using the calving grounds every year, while others did not. We estimated the probability of a bear spending time in the calving grounds during the calving season as a function of the bear’s sex and mean distance to the calving grounds with logistic regression. We found that as distance increased, the odds of a bear spending time in the calving grounds decreased, and that at any given distance the odds were greater for male bears than for female bears. Our results indicate that some bears in Newfoundland are likely caribou calf predators, while others are not, and that the sex and broad-scale distribution of bears influenced the probability of a bear participating in calf predation during the calving season. The probability distribution of calf-visiting bears could be used to develop management practices to mitigate the impact of bear predation on declining caribou herds in Newfoundland

Temporal variation in habitat use, co-occurrence, and risk among generalist predators and a shared prey

Generalist predators typically have broad diets, but their diets may become constrained when one species of prey becomes disproportionately available. Yet there is poor understanding regarding whether generalist predators exhibit stereotypic relationships with pulsed prey resources. We used telemetry data from 959 woodland caribou (146 adult females, 813 calves; Rangifer tarandus (L. 1758)), 61 coyotes (Canis latrans Say, 1823), and 55 black bears (Ursus americanus Pallas, 1780), to investigate how two generalist predators interacted with caribou neonates on the island of Newfoundland. We examined the similarity of patterns of habitat use between caribou and their predators across time and related this similarity to interspecific spatiotemporal co-occurrence and mortality risk for caribou neonates. The similarity in habitat use between coyotes and caribou mirrored variation in juvenile hazard risk, but had weak association with actual co-occurrence with caribou. Bears and caribou exhibited less similarity in habitat use during the calving season than coyotes and caribou. The relationship between habitat use of bear and caribou did not correspond with either co-occurrence patterns or overall risk for caribou neonates. Our work illustrates how risk for a prey species can be shaped differently based upon differences between the behavioural-strategies of generalist predator species.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Data from: Spatiotemporal heterogeneity in prey abundance and vulnerability shapes the foraging tactics of an omnivore

1. Prey abundance and prey vulnerability vary across space and time, but we know little about how they mediate predator-prey interactions and predator foraging tactics. To evaluate the interplay between prey abundance, prey vulnerability, and predator space use, we examined patterns of black bear (Ursus americanus) predation of caribou (Rangifer tarandus) neonates in Newfoundland, Canada using data from 317 collared individuals (9 bears, 34 adult female caribou, 274 caribou calves). 2. During the caribou calving season, we predicted that landscape features would influence calf vulnerability to bear predation, and that bears would actively hunt calves by selecting areas associated with increased calf vulnerability. Further, we hypothesized that bears would dynamically adjust their foraging tactics in response to spatiotemporal changes in calf abundance and vulnerability (collectively, calf availability). Accordingly, we expected bears to actively hunt calves when they were most abundant and vulnerable, but switch to foraging on other resources as calf availability declined. 3. As predicted, landscape heterogeneity influenced risk of mortality, and bears displayed the strongest selection for areas where they were most likely to kill calves, which suggested they were actively hunting caribou. Initially, the per-capita rate at which bears killed calves followed a type-I functional response, but as the calving season progressed and calf vulnerability declined, kill rates dissociated from calf abundance. In support of our hypothesis, bears adjusted their foraging tactics when they were less efficient at catching calves, highlighting the influence that predation phenology may have on predator space use. Contrary to our expectations, however, bears appeared to continue to hunt caribou as calf availability declined, but switched from a tactic of selecting areas of increased calf vulnerability to a tactic that maximized encounter rates with calves. 4. Our results reveal that generalist predators can dynamically adjust their foraging tactics over short time scales in response to changing prey abundance and vulnerability. Further, they demonstrate the utility of integrating temporal dynamics of prey availability into investigations of predator-prey interactions, and move towards a mechanistic understanding of the dynamic foraging tactics of a large omnivore

Survival data

Raw survival dat