Inside the Denver Zoo’s Effort to Save Colorado’s Rare Boreal Toad

On a misty day in June, a small group of biologists, conservationists, and filmmakers trek along a narrow, muddy path in a high alpine wetland in Pitkin County, Colorado. Light rain falls as the scientists haul large, translucent bags toward an unassuming pond surrounded by a band of mountain peaks.

“I took that rain as a really good omen,” Erica Elvove, senior vice president for conservation, engagement, and impact at the Denver Zoo, says later. “It signifies renewal and replenishment, and it felt like that’s exactly what we were doing up there.”

For nearly seven months, the Denver Zoo and Colorado Parks and Wildlife (CPW) have worked together to breed boreal toads, a high-elevation species native to Colorado, and to release their offspring into the wild. On June 28, that group of toad experts completed the months-long project by gently pushing 570 tadpoles from fish bags into their natural habitat to audible cheers. “All of our dreams and all of our hard work came to fruition in that moment,” Elvove says.

Boreal toads, which have historically been abundant across the West, are now critically endangered in Colorado. Biologists estimate there are only 800 adult toads left in the state, and the zoo’s conservation effort is the first time the amphibians have been bred to restore their depleted population in Colorado.

“Boreal toads are so important because they’re an indicator species for what’s happening in ecosystems and wetlands,” says Stefan Ekernas, director of conservation in Colorado at the Denver Zoo. “If there’s something that’s not healthy with the ecosystem, amphibians are the first ones where we will see that.”

The lumpy, speckled, grayish green toads face two major threats: chytrid fungus, a pathogen that’s invaded wetlands across the Western Hemisphere, causing the extinction of more than 90 species of amphibians, and increasing temperatures caused by climate change.

The Colorado-native toads are not yet considered endangered by the federal government, which bars researchers from accessing critical federal funding. So it’s up to institutions, like the zoo and CPW, to invest in efforts to save the amphibian.

“This first year has been an experimental year where we learn what we’re doing at this scale,” says Tom Weaver, assistant curator of ectotherms at the Denver Zoo. “I would like to see us releasing thousands.”

The Denver Zoo has been conserving endangered amphibian species for more than 15 years. In 2019, the zoo was the first in the nation to breed boreal toads and release them in southwest Utah.

Biologists say it will take several years to bring the boreal toad population back to healthy numbers, but in partnership with CPW, the zoo and its amphibian experts hope to do just that. The community is invited to help. Starting this summer, the Denver Zoo will collaborate with local volunteers, dubbed “community scientists,” to monitor the toads’ habitat, identify future sites for reintroduction, and locate unknown populations of these squishy toads. Those who are interested can sign up to be a part of the Boreal Toad Conservation Team here.

“The way forward for conservation is making sure everyone is aware of the need to save wildlife,” Elvove says. “And we’re giving people a very tangible way to participate in protecting it with us.”

(Read More: Inside the Denver Zoo’s New Animal Hospital)