Behavioral “bycatch” from camera trap surveys yields insights on prey
responses to human-mediated predation risk
Abstract
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.