Discerning the Environmental Drivers of Annual Migrations in an Endangered Amphibian
2019
Brooks, George C. | Smith, Jennifer A. | Gorman, Thomas A. | Haas, Carola A.
The prevalence of studies that discern the drivers of animal migrations is increasing exponentially, in line with raised concerns over climate-driven shifts in phenological patterns. Amphibians that breed in ephemeral wetlands are particularly vulnerable owing to the stochastic nature of their breeding habitat and high survival and reproductive costs associated with untimely migrations. Knowledge of the effects of climatic cues on the timing of amphibian migration and breeding phenologies is required to understand the potential consequences of climate change and to inform conservation plans for at-risk species. Here we use six years of count data from Eglin Air Force Base, Florida, U.S., collected between 2010 and 2016, to model the phenology of migrations of Ambystoma bishopi. Models were fit with a negative binomial error distribution, with daily values of temperature and precipitation as covariates. Models were compared in an AIC framework. We found that salamander movement was strongly tied to environmental cues. A proclivity to move over a medial range of temperatures and precipitation resulted in a ‘Goldilocks’ set of conditions that facilitate migration. We also discovered a role for endogenous drivers of movement, with day of year predicting above-ground activity regardless of environmental conditions. These results contribute to our basic knowledge of the behavior of A. bishopi and provide managers with useful metrics to maximize the efficacy of conservation actions. More broadly, the methods employed within have utility to amphibian researchers to help predict the effects of climate change and tailor management strategies accordingly.
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