Effects of snowpack, temperature, and disease on the demography of a wild population of amphibians

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Understanding the demographic consequences of interactions among pathogens, hosts, and weather conditions is critical in determining how amphibian populations respond to disease and in identifying site-specific conservation actions that can be developed to bolster persistence of amphibian populations. We investigated population dynamics in Boreal Toads (Anaxyrus boreas) relative to abiotic (fall temperatures and snowpack) and biotic (the abundance of another anuran host and disease) characteristics of the local environment in Wyoming, USA. We used capture–recapture data and a multistate model where state was treated as a hidden Markov process to incorporate disease state uncertainty and assess our a priori hypotheses. Our results indicated that snowpack during the coldest week of winter is more influential to toad survival, disease transition probabilities, and the population-level prevalence of the amphibian chytrid fungus (Batrachochytrium dendrobatidis) in the spring, than temperatures in the fall or the presence of another host. As hypothesized, apparent survival at low (i.e., <25 cm) snowpack (0.22; confidence interval [CI] = 0.15–0.31) was lower than apparent survival at high snowpack (90.65; CI = 0.50–0.78). Our findings highlight the potential for local environmental factors, like snowpack, to influence disease and host persistence, and demonstrate the ecological complexity of disease effects on population demography in natural environments. This work further emphasizes the need for improved understanding of how climate change may influence the relationships among pathogens, hosts, and their environment for wild animal populations challenged by disease.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Effects of snowpack, temperature, and disease on the demography of a wild population of amphibians
Series title Herpetologica
DOI 10.1655/0018-0831-76.2.132
Volume 76
Issue 2
Year Published 2020
Language English
Publisher BioOne
Contributing office(s) Fort Collins Science Center
Description 12 p.
First page 132
Last page 143
Country United States
State Wyoming
Other Geospatial Bridger-Teton National Forest, Togwetee Pass
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