An assessment of the limiting factors for boreal toads in the La Barge Creek watershed
July 2022 - June 2025
- Wyoming Game & Fish Department
Boreal toads (Anaxyrus boreas boreas) were once widespread and common but have suffered substantial population declines in the Rocky Mountain region. In Wyoming, boreal toads are a Species of Greatest Conservation Need (NSS1, Tier 1) and are designated by the Forest Service as a Sensitive Species. Declines have been attributed to climate change, habitat loss and alteration, and morbidity and mortality from the fungal pathogen Batrachochytrium dendrobatidis (Bd). Southern boreal toad populations in Colorado have shown substantial declines, whereas populations in the northern Wyoming Range appear to have remained relatively stable in the recent past.
Mechanisms underlying the decline remain unstudied but may include the introduction of Bd (~2003-2006) and/or habitat loss associated with a reclamation treatment that removed beaver dams (~2000-2006). Previous surveys, however, were not conducted nocturnally at potential breeding sites, when detectability of toads is highest. Given the on-going and range-wide population declines of boreal toads, including in parts of Wyoming, understanding of boreal toad population status and drivers of population dynamics in the La Barge watershed is timely and important.
The project is a collaboration of researchers between the USGS Wyoming Cooperative Fish & Wildlife Research Unit and state partners at the Wyoming Game & Fish Department.
Movement patterns will be used to assess home range size and habitat selection. We will assess habitat selection at both large (e.g., terrestrial vs. aquatic) and fine (microhabitat) scales. In addition, we will specifically evaluate individual movement patterns, habitat selection, and extent of mortality from individuals in relation to roads. Lastly, we will note any mortalities and their cause (e.g., disease, predation, trampling).