Time-averaging voles match density with long-term habitat quality

Area of Science:

• Ecology
• Behavioral Ecology
• Evolutionary Biology

Background:

• Organisms ideally select habitats offering the greatest fitness.
• Habitat selection strategies become complex when environmental quality fluctuates over time.
• Theory predicts individuals' long-term distribution matches mean habitat quality, but current quality is undermatched.

Purpose of the Study:

• To test the prediction that organisms match long-term mean habitat quality rather than current quality.
• To investigate dispersal strategies in response to temporally varying habitat quality.
• To understand how environmental fluctuations influence habitat selection and population distribution.

Main Methods:

• Controlled experiments using meadow vole populations in field enclosures.
• Manipulation of resource abundance (supplemental feeding) to create varying habitat quality.
• Measurement of vole response using giving-up densities (GUDs) in artificial foraging patches and live-trapping.

Main Results:

• Vole GUDs declined with increased resource supply, independent of short-term population density.
• Population densities were proportional to the long-term mean habitat quality, not current conditions.
• Sex ratios and juvenile habitat occupation patterns supported the time-averaged habitat matching interpretation.

Conclusions:

• Meadow vole dispersal strategies align with predictions of time-averaged habitat matching.
• Organisms' space-use strategies converge towards behavioral and evolutionary optima, even with fluctuating resources.
• This study provides empirical support for theoretical models of habitat selection under environmental variability.