Amphibians
Wyoming Toad
Anaxyrus baxteri · also called Baxter's toad
Within living memory, people in the Laramie Basin of Wyoming swept toads off their porches on summer nights. Within about thirty years, those toads were gone from the wild, and the species survived only because a handful of them were carried into zoos. The Wyoming toad is one of the sharpest amphibian declines ever recorded in North America.
Overview
Anaxyrus baxteri is a small, warty toad, usually 5 to 6 cm long, brown to grey-green with a pale mid-back stripe. It is adapted to a harsh setting — a cold, high, short-grass plain at around 2,200 m elevation — where it feeds on ants and beetles at pond edges and breeds in shallow, sun-warmed water. Its entire natural range is a single Wyoming valley, which left it with no backup population anywhere else.
The collapse
The toad was considered common into the 1950s. By the mid-1980s it had all but disappeared. The decline lines up with the arrival of amphibian chytrid fungus, a skin disease that has driven crashes in frogs and toads worldwide, and it was likely compounded by pesticide spraying, changes to basin irrigation, and the species’ naturally tiny range. By 1991 a single breeding site remained at Mortenson Lake, and when that failed the Wyoming toad was declared extinct in the wild.
A species on life support
Every Wyoming toad alive today descends from the small group taken into captivity. A network of zoos and federal hatcheries keeps assurance colonies, breeds the toad each year, and releases tens of thousands of tadpoles and young toads into protected Laramie Basin wetlands. Since the 2010s, biologists have found wild-laid eggs and locally raised adults in some years — the first sign that released toads can complete their life cycle on their own.
Status
The Wyoming toad remains Extinct in the Wild on the IUCN Red List. Chytrid fungus is still present in the basin, winters are severe, and drought shrinks the ponds, so the reintroduced population is not yet self-sustaining. Its future depends on continued captive breeding, disease management, and wetland protection.
Wyoming Toad: common questions
Why did the Wyoming toad nearly go extinct?
There is no single agreed cause, but the timing points to disease. The collapse in the 1970s and 1980s coincided with the spread of the amphibian chytrid fungus, which attacks the skin toads use to breathe and balance their salts, and the fungus is still present in the Laramie Basin today. Aerial spraying of pesticides for mosquitoes and crop pests across the basin, changes to irrigation and wetland flooding, predation, and a naturally tiny range that left no reservoir population elsewhere are all thought to have added to the pressure. The small gene pool of the survivors makes recovery harder.
What does extinct in the wild mean here?
It is a formal conservation category for a species that survives only in captivity or as a reintroduced population that cannot yet sustain itself. For the Wyoming toad it means that after the last natural breeding site failed in the early 1990s, every living toad descended from a small group taken into zoos. Animals released since then have bred in some years, but the population still needs regular restocking to persist, so it does not yet qualify as truly wild again. Moving it back to a lower-risk category depends on several consecutive years of natural recruitment.
Which zoos breed the Wyoming toad?
A coordinated program run under the Association of Zoos and Aquariums involves institutions including the Saratoga National Fish Hatchery in Wyoming, the Cheyenne Mountain Zoo, the Toledo Zoo, the Detroit Zoo, and several others, working alongside the US Fish and Wildlife Service and the Wyoming Game and Fish Department. Each facility keeps an assurance colony, produces egg strings under controlled conditions, and ships tadpoles and young toads back to Wyoming for release. Spreading the population across many sites protects it against a disease outbreak or accident wiping out the species in one stroke.
Is the Wyoming toad recovering?
Slowly and unevenly. The releases have re-established toads at several Laramie Basin wetlands, and in some years since the mid-2010s biologists have documented wild-laid eggs and young toads that grew up on site rather than in a zoo, which is real progress. But numbers swing sharply with winter severity, drought, and chytrid outbreaks, and no site yet holds a population that would survive without continued stocking. The recovery is best described as ongoing and fragile rather than secure.