Searching for One of Our Most Endangered Amphibians

Biologists take to the field in search of the Wyoming toad, a species that many are working hard to bring back from the brink.

It took 21 minutes of slow zig-zagging to cover a mere couple hundred meters of shoreline. I went at a snail’s pace, walking through wet soils thickly covered in grasses and sedges, all the time staring at the ground, hoping to catch a glimpse of movement. Each time, I had to hope that movement was not a spider, a vole or the wind playing tricks on my eyes. The goal, after all, was to find a Wyoming toad, one of the most endangered amphibians in North America.

Teamwork in the Search for Endangered Toads

The Wyoming toad is only found in one place in the entire world: the Laramie Basin of southern Wyoming. It used to occupy most floodplains, ponds, and seepage lakes in the region. In the mid-1970s changes in hydrology, spraying of insecticides, disease, and changes in climate combined to make it difficult for this species survive.

Populations crashed in the mid-1970s, and the toad was listed as endangered in 1984. By 1989, it was clear that experts needed to take drastic measures. They captured the last 10 surviving wild toads to start a captive breeding program – a last resort to stave off extinction. While the captive breeding program was coming online, the U.S. Fish and Wildlife Service acquired land where the last surviving population had been captured. In 1993 this land became The Mortenson Lake National Wildlife Refuge, and would act as an initial reintroduction site for the captive breeding program.

The breeding program now involves eight zoos, one fish hatchery, and the University of Wyoming Red Buttes Environmental Laboratory. Reintroductions started in 1995, with the captive breeding program making more releases possible each year. Until 2008, about 50 wild Wyoming toads were surviving and reproducing at Mortenson. But then, the population crashed. In 2011 and 2012, only a single wild adult toad was found during the annual surveys. Starting in 2012, researchers at the University of Wyoming began a new method of “soft” releases, where tadpoles and juveniles are placed at Mortenson inside a cage to protect them while they adjust to their new wild habitat. So far, this strategy appears to be helping, and more toads are surviving.

All this is how, earlier this summer, I found myself combing that marshy shoreline as part of the annual population surveys. Along with other volunteers and with employees of the U.S. Fish and Wildlife Service, we spent two days searching the Mortenson Lake National Wildlife Refuge for the endangered Wyoming toad.

Spot, Catch, and Check

It was an interesting and exciting couple of days. Once we spotted an individual toad, we had to catch it gently but quickly, before it could hop back into the grass and disappear. Holding on to the small toads, we took measurements of their weight, length, and general health. We swabbed them to test for the fungal infection Batrachochytrium dendrobatidis (otherwise known as Bd or chytrid), which is decimating amphibians around the world, and is a known problem for the Mortenson population of Wyoming toads. We also checked for any identification marks, such as PIT tags under their skin (similar to a microchip that your pet dog would have) or neon markers in their feet that would have been placed on them in captivity. The different color combinations near their feet can inform the Fish and Wildlife Service if the toad was captive bred, when the toad was released, and if it was a soft release. No colors might mean that the toad was a “hard release” as a tadpole or juvenile/adult, or might even have hatched naturally in the wild.

Don’t count these toads out!

Most people will never see a Wyoming toad in their lives. Odds are that before you read this, you probably didn’t even know that they existed. And why would you, especially if you don’t live nearby? Wyoming toads were never widespread. They aren’t conspicuous, like brightly colored birds, or traditionally charismatic, like wolves or bears. But they’re still important. Like all life, they have a role to play in maintaining a healthy ecosystem. They represent the unique biodiversity of the Laramie Basin of southern Wyoming. And they have a right to continue to exist – not be driven extinct and forgotten.