Apex predators exploit advantageous snow conditions across hunting modes.

Area of Science:

• Ecology and wildlife biology
• Climate change impacts on ecosystems
• Predator-prey dynamics

Background:

• Apex predators rely on functional traits and habitat features for hunting efficiency.
• Climate change alters snow cover, potentially affecting predator-prey interactions and ecosystem-wide impacts.
• Hunting mode is a key functional trait influencing predator effectiveness in different environments.

Purpose of the Study:

• To investigate the effects of snow depth and density on the movement and kill site selection of cougars (stalking predators) and wolves (coursing predators).
• To understand how different hunting strategies interact with snow conditions.
• To predict potential impacts of climate change on large carnivore hunting success and predator-prey dynamics.

Main Methods:

• Coupled a physically based snow model with telemetry data and kill site investigations.
• Utilized data from 50 cougars, 14 wolves, 142 mule deer, and 90 white-tailed deer in Washington state (2017-2021).
• Generated step selection functions incorporating deer distribution, snow properties, and landscape characteristics.

Main Results:

• Snow depth and density strongly influenced cougar movements and kill site selection, with a preference for dense, moderate-depth snow.
• Wolves showed a weaker selection for shallow, low-density snow, avoiding deeper snow unless very dense.
• Snow properties were a critical driver of movement for both predator types, regardless of hunting strategy.

Conclusions:

• Snow is a crucial element for large carnivore movement and hunting success, irrespective of their hunting mode.
• Diminishing snowpack due to climate warming may reduce hunting success for multiple large carnivore species.
• Altered predator-prey dynamics resulting from reduced snowpack could lead to cascading ecosystem-wide effects.