Evaluating prey switching in wolf-ungulate systems

Area of Science:

• Ecology
• Conservation Biology
• Wildlife Management

Background:

• Wolf restoration is a key conservation practice in North America and Europe.
• Understanding the ecosystem effects of returning apex predators like wolves is complex and debated.
• Existing models often simplify wolf-ungulate interactions, neglecting prey switching in multi-prey systems.

Purpose of the Study:

• To develop a mathematical model predicting predator diet composition in a wolf-elk-bison system.
• To incorporate factors like prey vulnerability, predator preference, and prey biomass into the model.
• To analyze the dynamics of wolf dietary shifts and the occurrence of prey switching.

Main Methods:

• Constructed a predator diet model using insights from small taxa experiments and field data.
• Incorporated differential vulnerability of elk and bison to wolf predation.
• Included parameters for wolf preference, prey biomass, and the possibility of prey switching.

Main Results:

• The model demonstrates that wolf diets shift with changes in the relative abundance of elk and bison.
• Dietary shift dynamics are influenced by prey preference, vulnerability, abundance, and prey switching.
• An abrupt dietary shift occurs only when elk are scarce relative to bison; prey switching leads to a more gradual shift.

Conclusions:

• The model provides a framework for empirically evaluating prey switching in restored wolf-two-prey systems.
• Model coefficients have biological interpretations and can be estimated from field data.
• Research into prey switching is vital for understanding predator-prey dynamics in wolf-ungulate systems.