Cooperative Fish and Wildlife Research Units Program: Wyoming
Education, Research and Technical Assistance for Managing Our Natural Resources

Barrile, G.M., A.W. Walters, M. Webster, and A.D. Chalfoun. 2021. Informed breeding dispersal following stochastic changes to patch quality in a pond-breeding amphibian. Journal of Animal Ecology 10.1111/1365-2656.13503


1. The unidirectional movement of animals between breeding locations (i.e., breeding dispersal) has profound implications for the ecological and evolutionary dynamics of spatially structured populations. In spatiotemporally variable environments, individuals are expected to adjust their dispersal decisions in accordance with fitness prospects in a given breeding patch.
2. A paucity of empirical work limits our understanding of the ability of animals to depart from low quality breeding patches and settle in high quality breeding patches (i.e., adaptive breeding dispersal). We examined the capacity of individuals to respond to stochastic changes in habitat quality via adaptive breeding dispersal in a pond-breeding amphibian.
3. We conducted a five-year (2015–2019) capture-recapture study of boreal toads Anaxyrus boreas boreas (n = 1100) that breed in beaver ponds in western Wyoming, USA. During early spring of 2017, an extreme flooding event destroyed several beaver dams and resulted in the loss of breeding habitat. We used multi-state models to investigate how temporal changes in pond characteristics influenced breeding dispersal and determined whether movement decisions were adaptive with respect to prospects for reproductive fitness.
4. Boreal toads exhibited adaptive breeding dispersal; individuals more often departed from low quality breeding ponds (without successful metamorphosis) and settled in high quality breeding ponds (with successful metamorphosis). Movement decisions were associated with pond characteristics altered as a result of beaver dam destruction, including decreases in pond depth and increased emergent vegetation. Individuals were more likely to depart from shallow ponds with high vegetation cover and settle in deep ponds with low vegetation cover. Similarly, the probability of metamorphosis was greater in deep ponds with low vegetation cover, suggesting boreal toads may use pond depth and vegetation cover as cues to assess the fitness prospects of a breeding patch and adjust movement decisions accordingly.
5. We demonstrate that stochastic variability in environmental conditions and habitat quality can underpin dispersal behavior in amphibians. Our study highlights the mechanistic linkages between habitat change, movement behavior, and reproductive success, which is critical to our understanding of how wild animals respond to rapid environmental change.