Habitat selection reveals state-dependent foraging trade-offs in a temporally autocorrelated environment

Abstract

We use theories of risk allocation to inform trade-offs between foraging in a rich and risky habitat versus using a poor but safe alternative. Recent advances in the theory predict that the length of exposure to good or bad conditions governs risk allocation, and thus habitat choice, when patterns of environmental risk are autocorrelated in time. We investigate the effects of these factors with controlled experiments on a small soil arthropod (Folsomia candida). We subjected animals to nine temporally autocorrelated 16-day feeding treatments varying in both the proportion (0.25, 0.50, and 0.75) and duration (short, medium and long intervals) of time when food was present and absent. We assessed foraging trade-offs by the animals' choice of occupying a risky dry habitat with food (rich) versus a safe moist habitat with no food (poor). Irrespective of autocorrelation in conditions, the proportion of time spent with no food primarily determined habitat selection by these collembolans. Our results imply an energetic threshold below which F. candida are forced to forage in rich and risky habitat despite the possibility of mortality through desiccation. The link to energetic thresholds suggests the possibility of employing state-dependent habitat selection as a leading indicator of habitat change.

Keywords:

• adaptive behaviour
• energetic state
• Folsomia candida
• habitat selection
• optimal foraging
• risk allocation

Acknowledgements

We thank B. Kotler for kindly inviting us to contribute to this special edition celebrating the science and life of Karen Embar. We remember Karen's short visit to our laboratory and research group, and her spirited discussions on evolutionary ecology with great fondness. Our collective science is poorer through her untimely passing. We thank Dr G. Boiteau for generously providing our lab with stock populations of F. candida, as well as D. Durston, D. Start, and our Evolutionary Ecology Research Team for contributing their time and effort to pilot studies assessing the potential of habitat selection by F. candida. The manuscript was improved by candid suggestions from B. Kotler and anonymous reviewers. We gratefully acknowledge support provided to A. Bannister by Lakehead University and the Northern Lake Superior Research Award.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Additional information

Funding

This research was supported by Canada's Natural Sciences and Engineering Research Council [grant number 116430-2013].