Data from: Interactive effects of wildfires, season, and predator activity shape mule deer movements

Wildfires are increasing in size, frequency, and severity due to climate
change and fire suppression, but the direct and indirect effects on
wildlife remain largely unresolved. Fire removes forest canopy, which can
improve forage for ungulates but also reduce snow interception, leading to
a deeper snowpack and potentially increased vulnerability to predation in
winter. If ungulates exhibit predator-mediated foraging, burns should
generally be selected for in summer to access high-quality forage and
avoided in winter to reduce predation risk in deep snow. Fires also
typically increase the amount of deadfall and initiate growth of dense
understory vegetation, creating obstacles that may confer a hunting
advantage to stalking predators and a disadvantage to coursing predators.
To minimize risk, ungulates may therefore avoid burns when and where
stalking predators are most active, and use burns when and where coursing
predators are most active. We used telemetry data from GPS-collared mule
deer (Odocoileus hemionus), cougars (Puma concolor), and wolves (Canis
lupus) to develop step selection functions to examine how mule deer
navigated species-specific predation risk across a landscape in northern
Washington, USA that has experienced substantial wildfire activity during
the past several decades. We considered a diverse array of wildfire
impacts, accounting for both the severity of the fire and time since the
burn (1 to 35 years) in our analyses. We observed support for the predator
mediating foraging hypothesis: mule deer generally selected for burned
areas in summer and avoided burns in winter. In addition, deer increased
use of burned areas when and where wolf activity was high and avoided
burns when and where cougar use was high in winter, suggesting the hunting
mode of resident predators mediated the seasonal response of deer to
burns. Deer were not more likely to die by predation in burned than in
unburned areas, indicating that they adequately manage fire-induced
changes to predation risk. As fire activity increases with climate change,
our findings indicate the impact on ungulates will depend on tradeoffs
between enhanced summer forage and functionally reduced winter range,
mediated by characteristics of the predator community.