Abstract
Species’ distributions are influenced by a combination of landscape variables and biotic interactions with other species, including people. Grizzly bears and black bears are sympatric, competing omnivores that also share habitats with human recreationists. By adapting models for multi-species occupancy analysis, we analyzed trail camera data from 192 trail camera locations in and around Jasper National Park, Canada to estimate grizzly bear and black bear occurrence and intensity of trail use. We documented (a) occurrence of grizzly bears and black bears relative to habitat variables (b) occurrence and intensity of use relative to competing bear species and motorised and non-motorised recreational activity, and (c) temporal overlap in activity patterns among the two bear species and recreationists. Grizzly bears were spatially separated from black bears, selecting higher elevations and locations farther from roads. Both species co-occurred with motorised and non-motorised recreation, however, grizzly bears reduced their intensity of use of sites with motorised recreation present. Black bears showed higher temporal activity overlap with recreational activity than grizzly bears, however differences in bear daily activity patterns between sites with and without motorised and non-motorised recreation were not significant. Reduced intensity of use by grizzly bears of sites where motorised recreation was present is a concern given off-road recreation is becoming increasingly popular in North America, and can negatively influence grizzly bear recovery by reducing foraging opportunities near or on trails. Camera traps and multi-species occurrence models offer non-invasive methods for identifying how habitat use by animals changes relative to sympatric species, including humans. These conclusions emphasise the need for integrated land-use planning, access management, and grizzly bear conservation efforts to consider the implications of continued access for motorised recreation in areas occupied by grizzly bears.
Highlights
Interspecific interactions play a fundamental role in shaping species’ distributions and behavior [1], incorporating such relationships into species distribution models can be logistically challenging and complex [2]
There is little evidence that grizzly bears are negatively affected by black bear occurrence directly, it is postulated that high black bear densities might result in reduced reproduction by grizzly bears through exploitation competition, despite grizzly bears being able to dominate high-quality foraging through resource defense competition and direct interference competition [12,16]
Of the 182 monitored sites included in the analysis, grizzly bears were photographed at 84 locations and black bears were photographed at 74 locations
Summary
Interspecific interactions play a fundamental role in shaping species’ distributions and behavior [1], incorporating such relationships into species distribution models can be logistically challenging and complex [2]. Interspecific competition can lead to resource partitioning that allows multiple species that are ecologically similar to coexist on the same landscape [3,4], resulting in sympatry with niche divergence [5]. These interactions can be altered by anthropogenic factors such as human activity [6], which has the potential to affect individual behavior and habitat use, both key considerations in management and conservation planning [7]. There is little evidence that grizzly bears are negatively affected by black bear occurrence directly, it is postulated that high black bear densities might result in reduced reproduction by grizzly bears through exploitation competition, despite grizzly bears being able to dominate high-quality foraging through resource defense competition and direct interference competition [12,16]
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