The Detroit Zoological Society (DZS) is helping a species hop back from extinction!
The Wyoming toad was once found in abundance in the Laramie River Basin. However, catastrophic population declines were observed throughout the 1970s. By 1983, the Wyoming toad was thought to be extinct. Biologists could make no clear determination for the cause of the decline.
With a bit of luck, a small population of about 20 animals was rediscovered in 1987 at Mortenson Lake, bringing hope that the species could be saved. Rescuing the species by bringing it into captivity was the only option to avoid extinction.
Amphibian Chytrid Fungus and Preventing Amphibian Extinctions
Throughout the 1980s and 1990s, amphibian declines were common around the globe – something that puzzled biologists. At the time, there was no obvious answer as to why multiple amphibian species were rapidly disappearing in Australia, Central America and the United States. In 1998, the amphibian chytrid fungus – a microscopic primitive fungi – was discovered to be the cause of disease resulting in these declines. Biologists have attributed the amphibian chytrid fungus to be the primary cause of approximately 100 amphibian extinctions and to have impacted more than 700 amphibian species. No other wildlife disease has impacted biodiversity as much as this fungus.
The Wyoming toad is highly susceptible to the amphibian chytrid fungus. The National Amphibian Conservation Center at the Detroit Zoo was built in part as a response to the amphibian biodiversity crisis, which assisted in keeping some of the most imperiled species away from the edge of extinction. The Wyoming toads at Detroit Zoo live in a biosecure room, which keeps them safe from being potentially exposed to the disease!
Ex-situ rescue, which is when a species is brought out of the wild into captivity for conservation, is a last resort. Unfortunately, we are often left with no other options. Rescuing a species in captivity requires intensive management to maintain the population, and it’s a long-term commitment by a dedicated and passionate team.
Wyoming Toads at the DZS
The DZS was an early partner in rescuing Wyoming toads, welcoming our first toads in 1995. A Species Survival Program (SSP) was also formed in 1996 to organize efforts among zoo partners and the U.S. Fish and Wildlife Service. The amphibian team at the DZS has produced 10,730 Wyoming toad tadpoles, toadlets and adults for reintroduction since joining the program in 2001! These animals are bred at the DZS and later sent to Wyoming to be released into the wild. The Center for Zoo and Aquarium Animal Welfare and Ethics at the Detroit Zoo has also led studies that have helped improve the husbandry of Wyoming toads in captivity by comparing the preferences for substrate, which improves our care for this very important species.
Caring for Wyoming Toads at the Detroit Zoo
Mike Andrus is the primary colleague who takes care of the Wyoming toads at the DZS, and his years of experience in the amphibian department caring for these toads is one of the keys to Detroit Zoo’s success. Mike handles more than 30 toads at the Zoo
Mike Andrus is the primary colleague who takes care of the Wyoming toads at the DZS, and his years of experience in the amphibian department caring for these toads is one of the keys to Detroit Zoo’s success. Mike handles more than 30 toads at the Zoo, where he carefully cycles the temperature throughout the year, including when he places the toads in a refrigerator to hibernate. This process requires a lot of fine-tuning and experience – and prepares the toads, which are each equipped with their own individual ID to track genetics, for breeding.
Wyoming toad tadpole reintroductions
In June 2022, Mike traveled to Laramie, Wyoming to participate in the reintroduction of Wyoming toad tadpoles. Several thousand tadpoles were sent from SSP partners for reintroductions. It was a busy day, as tadpoles were placed in bags of about 100 animals and methodically distributed around reintroduction sites.
Tadpole reintroductions are very important to continue supporting the recruitment of new toads into the population. In the months following the tadpole reintroductions, hundreds of recently meta morphed toads are found — each one with the potential to make it to adulthood and breed in the wild.
Wyoming toad surveys
In August 2022, I participated in the Wyoming toad field surveys and an annual SSP meeting. The team was successful in finding many young toads, likely from tadpole reintroductions and some wild breeding. The most exciting part was finding more than 15 breeding-sized adults! Some of the toads had a small identification tag, demonstrating that reintroduced juveniles and adults from captivity are surviving in the wild.
Wyoming toads were found at all four field sites the team visited, a very good sign for a species that was once thought to be on the verge of extinction. Currently, there is no method to mitigate the amphibian chytrid fungus in the wild, but in recent years there are an increasing number of rediscoveries of species once thought to be extinct and vulnerable species persisting in the presence of chytrid.
We’re optimistic that the Wyoming toad will soon hop back from extinction!
Thank you to our SSP partners, who make saving this species possible:
• U.S. Fish and Wildlife Service
• Kansas City Zoo
• Cheyenne Mountain Zoo
• Omaha’s Henry Doorly Zoo and Aquarium
• Como Zoo
• Mississippi River Museum