Linking habitat selection and predation risk to spatial variation in survival

Area of Science:

• Ecology
• Wildlife Biology
• Conservation Science

Background:

• Habitat selection theory assumes chosen environments enhance fitness, but this is often untested.
• Predation risk gradients can be stronger drivers of vital rates than habitat selection patterns.
• Woodland caribou (Rangifer tarandus caribou Gmelin) survival is crucial for this threatened ungulate's conservation.

Purpose of the Study:

• To test the assumption that selected habitats confer enhanced fitness in woodland caribou.
• To investigate the independent and combined effects of resource selection and predation risk on adult female survival.
• To evaluate the temporal dynamics of habitat quality effects on survival.

Main Methods:

• Utilized Cox proportional hazards spatial survival modeling to analyze woodland caribou adult female survival.
• Separately measured spatial patterns of resource selection and predation risk.
• Developed and compared models defining habitat quality based on selection, risk, and their interactions.

Main Results:

• Resource selection function (RSF) values positively correlated with survival, but this relationship was non-ideal.
• Incorporating predation risk significantly improved survival models, revealing it as an additive source of mortality.
• Predation risk had instantaneous effects, while RSF-predicted habitat suitability had both instantaneous and seasonal effects on survival.

Conclusions:

• Woodland caribou exhibit non-ideal habitat selection, where resource availability does not fully mitigate predation threats.
• Predation risk is a critical, additive factor influencing survival beyond habitat selection alone.
• Spatially explicit predictions of population growth were generated by integrating survival and recruitment data.