August 29, 2023

Denver Zoo Debuts Boreal Toad Community Science Effort

How Coloradoans Are Helping the Effort to Conserve Boreal Toads

By: Sam Hengge, Boreal Toad Project Assistant 

How do modern zoos and aquariums meet the challenge of involving local communities in conservation efforts? One way Denver Zoo’s conservation team has sought to meet this challenge is through a brand-new community science program focused on Colorado’s endangered boreal toad (Anaxyrus boreas boreas). As a part of their participation with “Team Toad,” volunteers from throughout Colorado have been learning how to survey a variety of high-elevation wetlands in search of this rare amphibian. Within one summer of launching the program, community science efforts have already begun making an impact. 

Once widespread at elevations of 8,000-12,000ft in the southern Rocky Mountains, the boreal toad has largely disappeared from its historical range across the west. While boreal toad populations vary across surrounding states, in Colorado there are approximately 800 adult boreal toads remaining. Boreal toads are largely threatened by habitat loss and chytridiomycosis, a fungal pathogen leading to the decline of many amphibians worldwide. With over half of their breeding sites positive for chytrid, boreal toads have been largely susceptible to this disease. 

To help bring the boreal toad back from the brink of extinction in Colorado, Denver Zoo began assisting Colorado Parks and Wildlife in their conservation efforts by implementing a captive breeding program. Denver Zoo’s interest in boreal toads originally began in 2010 with a set of Utah boreal toads that were successfully bred and reintroduced in 2019. Following the success of these efforts, Denver Zoo shifted their focus towards Colorado boreal toads in 2022, leading to the successful breeding and reintroduction of their tadpoles/metamorphs back into the wild.  

To supplement captive breeding efforts, Denver Zoo also debuted a boreal toad community science project in the summer of 2022. After putting out the call for “Toad Trekkers,” Denver Zoo staff trained 76 interested community science volunteers from across the state to conduct amphibian surveys among target wetlands. Participants learned how to distinguish boreal toads from other amphibians and were taught how to swab specimens for chytrid. Additionally, volunteers conducted waterbody assessments for evaluating the quality of wetland habitats as potential reintroduction sites.  

In August 2022, a small group of Denver Zoo staff and volunteers found a boreal toad near Buena Vista, CO in a wetland where the species was believed to be absent after years without any sightings. As a result of this discovery, Colorado Parks and Wildlife altered how they were managing the wetland by halting a toad-stocking that had originally been planned in the area.  

This past summer, in addition to training a new round of “Toad Trekkers,” Denver Zoo surveyed a new set of wetlands with community science volunteers and made additional boreal toad discoveries. Following the success of the last two field seasons, Denver Zoo’s conservation team is hopeful that community science efforts will continue having a positive effect on boreal toad conservation in Colorado.  

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