| Chapter 2—Area Description and Resources19 |
LPP-7 show migratory bird concentrations for wetland birds, grassland birds, riparian birds, and raptors (Pocewicz et al. 2013). Pocewicz et al. (2013) used current migration literature and expert conservationists to get a clearer picture of where important bird migration habitat is throughout the region.
Mammals
Many species of small mammals live in the region, including the white-tailed prairie dog, muskrat, and American beaver, as well as multiple species of ground squirrel, mouse, vole, and shrew. The white-tailed prairie dog is considered a keystone species because species including black-footed ferret, swift fox, American badger, ferruginous hawk, and several other large raptors depend on prairie dogs as prey; species including black-footed ferret, burrowing owl, and swift fox depend on prairie dogs to provide burrows as cover and den substrate; and species including mountain plover and McCown’s longspur depend on prairie dogs for shortgrass and semibarren habitats. Black-footed ferrets, in particular, depend so strongly on prairie dogs that ferret recovery and management is, in effect, prairie dog management.
Four of Wyoming’s seven big game species, mule deer, white-tailed deer, elk, and pronghorn, are known to reside in or migrate through the project area.
Fish and Aquatic Invertebrates
Fish and aquatic invertebrate populations that were present before Euro-American settlement are not well known in much of the west, and the North Platte River basin, which contains the Laramie Plains, is no exception. The list of aquatic species in appendix E is short and likely incomplete, especially in regards to aquatic invertebrates. It is well accepted that there were no sport fish in the Laramie Plains, or elsewhere in the entire North Platte River basin, before Euro-American settlement (WGFD 2010). Small fish such as hornyhead chub and Iowa darter probably dominated fish assemblages, but these species were greatly affected by the deliberate introduction of various trout species and other exotic taxa, including carp, beginning during early Euro-American settlement and continuing until the present. It is believed that hornyhead chub is found only in the North Laramie River and the Lower Laramie River, and it is believed to be extinct in Montana, Colorado, North Dakota, South Dakota, Nebraska, and Kansas (WGFD 2010). Populations of native aquatic invertebrates were probably also dramatically changed by the introduction of nonnative fish.
Species of Special Concern
Several federally listed species live in, or have home ranges that overlap, the conservation area.
Wyoming Toad
The project area now supports one endangered species, the Wyoming toad (Anaxyrus (Bufo) baxteri). First described in 1946 by Dr. George T. Baxter, it is thought to be a glacial relict. The toad once flourished in the Laramie Plains, but in the 1970s the population dramatically declined, and by the 1980s, individuals were extremely rare (Baxter and Stromberg 1980, Stromberg 1981, Vankirk 1980, Baxter and Meyer 1982, Baxter and Stone 1985, Lewis et al. 1985). The species was federally listed as endangered in 1984 under the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.). In 1993, under the authority of the Endangered Species Act, Mortenson Lake Refuge was established for the protection of the last known Wyoming toad population. It is considered the most endangered amphibian in North America (IUCN 2012).
The historical distribution of the Wyoming toad, based on scientific records from Dr. George Baxter and Ronald Beiswenger’s research, includes the floodplain ponds and small seepage lakes associated with the Big and Little Laramie Rivers as well as other wetlands within the shortgrass communities of the Laramie Plains in Albany County, Wyoming (figure LPP-8). Current distribution is limited to Mortenson Lake Refuge and one nearby Safe Harbor Act site. There are very few Wyoming toads thought to be in the wild and approximately 500 in captivity. The small number of individuals is considered one of the severe threats to the toad. Another major threat to the Wyoming toad is infectious disease, including the amphibian fungus Batrachochytrium dendrobatidis (Bd) which has been linked to amphibian declines worldwide (Berger et al. 1998). Bd was documented in wild Wyoming toads from Mortenson Lake in 2000 and in 2001 (USFWS 2013). The other severe threat to the Wyoming toad that is discussed in the recovery plan is the lack of perpetually protected habitat. The proposed action directly addresses this severe threat to the Wyoming toad by protecting habitat that is needed for the next step of recovery and which is important for the future of Wyoming toad conservation.
Little is known about the habitat requirements for the Wyoming toad but the current thought is that the toad historically occurred in rivers and associated floodplains (lotic habitats) of the Big and Little Laramie Rivers and ponds and lakes (lentic habitats). Ongoing research, supported by the Service and a
