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Changing spring snow cover dynamics and early season forage availability affect the behavior of a large carnivore

Abstract

Changing climates are altering wildlife habitats and wildlife behavior in complex
ways. Here, we examine how changing spring snow cover dynamics and early season forage availability are altering grizzly bear (Ursus arctos) behavior postden emergence.

Telemetry data were used to identify spring activity dates for 48 individuals in
the Yellowhead region of Alberta, Canada. Spring activity date was related to snow
cover dynamics using a daily percent snow cover dataset. Snow melt end date, melt
rate, and melt consistency explained 45% of the variation in spring activity date. We
applied this activity date model across the entire Yellowhead region from 2000 to
2016 using simulated grizzly bear home ranges. Predicted spring activity date was
then compared with a daily spring forage availability date dataset, resulting in “wait
time” estimates for four key early season forage species. Temporal changes in both
spring activity date and early season forage “wait times” were assessed using nonparametric regression.

Grizzly bear activity date was found to have either remained constant (95%) or become earlier (5%) across the study area; virtually no areas withsignificantly later spring activity dates were detected. Similarly, the majority of “wait times” did not change (85%); however, the majority of significant changes in “wait times” for the four early season forage species indicated that “wait times” were lessening where changes were detected. Our results show that spring activity date is
largely dictated by snow melt characteristics and that changing snow melt conditions
may result in earlier spring activity. However, early season food stress conditions are
likely to remain unchanged or improve as vegetation phenology also becomes earlier.

Our findings extend the recent work examining animal movement in response to
changing phenology from migratory birds and ungulates to an apex predator, further
demonstrating the potential effects of changing climates on wildlife species.

Read the full paper here.

Citation

Rickbeil, GJM, Coops, NC, Berman, EE, McClelland, CJR, Bolton, DK, Stenhouse, GB. Changing spring snow cover dynamics and early season forage availability affect the behavior of a large carnivore. Glob Change Biol. 2020; 26: 62666275. https://doi.org/10.1111/gcb.15295

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