The Wyoming Toad SSP

Article excerpt

The origin of the Wyoming toad can be traced to about 10,000 years ago when it became isolated from its ancestral stock, the Manitoba or Canadian toad (Bufo hemiophrys), around the end of the Pleistocene Epoch. The ranges of the two species are separated by approximately 500 miles (800 kilometers). The Wyoming toad currently is found only in the State's Laramie Basin. This burrowing animal inhabits floodplains, ponds, and ditches in the short grass regions of the basin.

Wyoming toads (Bufo hemiophrys baxteri) were once abundant in the wetlands and irrigated meadows of Wyoming's southeastern plains. However, by the 1970's the population had declined drastically and was confined to privately owned lands surrounding Mortenson Lake. In 1984, the Fish and Wildlife Service (FWS) recognized the species' precarious status by listing the Wyoming toad as endangered. To protect the last population, The Nature Conservancy (TNC) stepped in and purchased the lake and surrounding lands, totaling approximately 1,800 acres (730 hectares). But populations continued to decline, and by 1994 the species was extinct in the wild. Only captive populations remained.

In December of 1996, the American Zoo and Aquarium Association (AZA) approved a Species Survival Plan (SSP) that formalized a cooperative program of the AZA, FWS, and Wyoming Game and Fish Department (WGF). This program was designed to restore the Wyoming toad, one of the most endangered amphibians in the United States, to a secure status in the wild.

The reintroduction story began in 1988, when a small number of toads were taken from Mortenson Lake to WGF facilities for captive breeding. In 1992, the FWS purchased some of the Wyoming toad's last habitat from TNC and established the Mortenson National Wildlife Refuge (NWR). That same year, tadpoles and toadlets were released at Lake George and Rush Lake on Hutton NWR in an effort to establish a second wild population. By 1994, it was apparent that emergency measures were needed. In an effort to prevent the animal from becoming extinct, the last remaining toads were captured and a more intensive captive breeding program was initiated. The captive population greatly increased by 1995, with the help of several AZA affiliated zoos and the WGF facilities.

Wyoming toads are now housed at eight AZA affiliated zoos: Central Park (NY), Cincinnati (OH), Detroit (MI), Henry Doorly (NE), Houston (TX), Sedgwick County (KS), St. Louis (MO), and Toledo (OH). Two government facilities, the Saratoga National Fish Hatchery (WY) and Sybille Wildlife Research Center (WY), also have captive populations. Diane Callaway of the Henry Doorly Zoo maintains a species studbook to manage the genetics of the entire captive breeding population. …