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Behavioral “bycatch” from camera trap surveys yields insights on prey responses to human-mediated predation risk
Burton, Cole; Beirne, Christopher; Sun, Catherine; Granados, Alys; Procko, Michael; Chen, Cheng; Fennell, Mitchell; Constantinou, Alexia; Colton, Christopher; Tjaden-McClement, Katie; Fisher, Jason; Burgar, Joanna — 2022-06-27 <p>Human disturbance directly affects animal populations but indirect effects of disturbance on species behaviors are less well understood. Camera traps provide an opportunity to investigate variation in animal behaviors across gradients of disturbance. We used camera trap data to test predictions about predator-sensitive behavior in three ungulate species (caribou Rangifer tarandus; white-tailed deer, Odocoileus virginianus; moose, Alces alces) across two boreal forest landscapes varying in disturbance. We quantified behavior as the number of camera trap photos per detection event and tested its relationship to predation risk between a landscape with greater industrial disturbance and predator abundance (Algar) and a “control” landscape with lower human and predator activity (Richardson). We also assessed the influence of predation risk and habitat on behavior across camera sites within the disturbed Algar landscape. We predicted that animals in areas with greater predation risk (more wolf activity, less cover) would travel faster and generate fewer photos per event, while animals in areas with less predation risk would linger (rest, forage), generating more photos per event. Consistent with predictions, caribou and moose had more photos per event in the landscape where predation risk was reduced. Within the disturbed landscape, no prey species showed a significant behavioral response to wolf activity, but the number of photos per event decreased for white-tailed deer with increasing line of sight (m) along seismic lines (i.e. decreasing visual cover), consistent with a predator-sensitive response. The presence of juveniles was associated with shorter behavioral events for caribou and moose, suggesting greater predator sensitivity for females with calves. Only moose demonstrated a positive association with vegetation productivity (NDVI), suggesting that for other species influences of forage availability were generally weaker than those from predation risk. Behavioral insights can be gleaned from camera trap surveys and provide information about animal responses to predation risk and the indirect impacts of human disturbances.</p> https://creativecommons.org/publicdomain/zero/1.0/
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Data from: Density-dependent space use affects interpretation of camera trap detection rates
Broadley, Kate; Burton, Cole; Boutin, Stan; Avgar, Tal — 2020-11-20 <p>Camera-traps (CTs) are an increasingly popular tool for wildlife survey and monitoring. Estimating relative abundance in unmarked species is often done using detection rate as an index of relative abundance, which assumes a positive linear relationship with true abundance. This assumption may be violated if movement behavior varies with density, but the degree to which movement is density-dependent across taxa is unclear. The potential confounding of population-level relative abundance indices by movement depends on how regularly, and by what magnitude, movement rate and home-range size vary with density. We conducted a systematic review and meta-analysis to quantify relationships between movement rate, home range size, and density, across terrestrial mammalian taxa. We then simulated animal movements and CT sampling to test the effect of contrasting movement scenarios on CT detection rates. Overall, movement rate and home range size were negatively correlated with density and positively correlated with one another. The strength of the relationships varied significantly between taxa and populations.  In simulations, detection rates were related to true abundance but underestimated change, particularly for slower moving species with small home ranges. In situations where animal space use changes markedly with density, we estimate that up to thirty percent of a true change in abundance may be missed due to the confounding effect of movement, making trend estimation more difficult. The common assumption that movement remains constant across densities is therefore violated across a wide range of mammal species. When studying unmarked species using CT detection rates, researchers and managers should consider that such indices of relative abundance reflect both density and movement. Practitioners interpreting changes in detection rates should be aware that observed differences may be biased low relative to true changes in abundance, and that further information on animal movement may be required to make robust inferences on population trends.</p>
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Global camera trap synthesis highlights the importance of protected areas in maintaining mammal diversity
Chen, Cheng; Burton, Cole — 2022-01-04 <p>The establishment of protected areas (PAs) is a central strategy for global biodiversity conservation. While the role of PAs in protecting habitat has been highlighted, their effectiveness at protecting mammal communities remains unclear. We analyzed a global dataset from over 8,671 camera traps in 23 countries on four continents that detected 321 medium- to large-bodied mammal species. We found a strong positive correlation between mammal taxonomic diversity and the proportion of a surveyed area covered by PAs at a global scale (b = 0.39, 95% CI = 0.19, 0.60) and in Indomalaya (b = 0.69, 95% CI = 0.19,1.2), as well as between functional diversity and PA coverage in the Nearctic (b = 0.47, 95% CI = 0.09, 0.85), after controlling for human disturbances and environmental variation. Functional diversity was only weakly (and insignificantly) correlated with PA coverage at the global scale (b =0.22, 95% CI = -0.02, 0.46), pointing to a need to better understand the functional response of mammal communities to protection. Our study provides important evidence of the global effectiveness of PAs in conserving terrestrial mammals and emphasizes the critical role of area-based conservation in a post-2020 biodiversity framework.</p>
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Data and R Code from Granados et al. 2023, Mammalian predator and prey responses to recreation and land use across multiple scales provide limited support for the human shield hypothesis, Ecology and Evolution.
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Granados, Alys; Sun, Catherine; Fisher, Jason T.; Ladle, Andrew; Dawe, Kimberly; Beirne, Christopher; Boyce, Mark; Chow, Emily; Heim, Nicole; Fennell, Mitchell; Klees van Bommel, Joana; Naidoo, Robin; Procko, Michael; Stewart, Frances; Burton, Cole — 2023 Data from Granados et al. 2023 Mammalian predator and prey responses to recreation and land use across multiple scales provide limited support for the human shield hypothesis, Ecology and Evolution https://creativecommons.org/licenses/by/4.0/legalcode

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