boreal toad

New research on boreal toads

Gabe Barrile’s research on toad habitat use has been accepted at American Naturalist

Infectious diseases pose a serious threat to the health of people, domestic animals, and wildlife alike. The chytrid fungus, for example, has already caused the extinction of over 100 amphibian species and continues to plague hundreds more across the globe. Boreal toads, once common in high-elevation habitats across the Rocky Mountain West, have suffered severe declines due to the chytrid fungus in recent decades. Boreal toads in western Wyoming, however, persist despite high infection rates with the fungus.

Gabe Barrile, a graduate researcher from the University of Wyoming, along with faculty advisors Anna Chalfoun and Annika Walters, study the lives of boreal toads in the mountains of western Wyoming. Toads usually take refuge under riparian willows or in small mammal burrows. Occasionally, however, the researchers observe toads in open environments, often basking in the exposed sunlight. They hypothesized that use of sheltered habitats, which are cool and moist, versus the use of open habitats, which are warm and dry, may be related to whether an individual toad is infected with the chytrid fungus. To test this idea, they obtained disease samples and recorded body temperatures of radio-tracked toads during the summer of 2016. They then matched disease and thermal data to the habitats that toads used through time.

The researchers found that wild boreal toads use moist, sheltered habitats when disease-free but move to warmer, more open habitats when infected. Switching habitats in response to infection appears to be advantageous, as increased warmth in open habitats is associated with the clearing of infection, likely via the elevation of body temperature. These findings suggest small-scale microhabitat manipulation to create warm patches may comprise an effective mitigation action against the chytrid fungus, and possibly other amphibian diseases. More broadly, a deeper understanding of disease dynamics better equips us to improve human and animal health in the face on infectious onslaughts.