Many different types of wildlife use abandoned mines for either permanent or temporary habitat.

Bats
Abandoned mines provide very good bat habitat. Contrary to their much-maligned image, bats are ecologically and economically critical to the well being of the nation. The Mexican free-tailed bat weighs approximately one ounce and will consume one-half its body weight in insects each night. The mathematical result is that one large (20-million) colony of bats consumes over 150 tons of insects each night. A much smaller colony may consume almost 2 tons of insects each night. Seed production from an agave plant (the source for tequila) drops to a fraction of the normal without bats as pollinators. And yet, over half of the 43 species living in the U.S. are endangered or on the candidate list for endangered species. As their traditional habitats such as caves and tree hollows are being disturbed by human intrusion, bats are becoming more and more dependent on abandoned mine sites for suitable habitat. Many of the 43 species, including endangered species, have been observed using abandoned mines either as permanent roosts or temporary stops during migration. Abandoned mines provide microclimates similar to caves, suitable for rearing young, hibernation, and rest stops during migration in the spring and fall. Closure of mine openings without a biological survey can trap and destroy an entire colony of bats.

Bat Conservation International (BCI) is a non-profit organization formed to promote the conservation of bats and bat habitat. The Office of Surface Mining signed a Memorandum of Understanding with BCI in 1998 to address the significance of protecting bat habitat while closing abandoned mines.

New Mexico is home to 27 species of bats; 19 are listed as a Species of Concern, three species are considered threatened and one species is considered endangered. The various species found in New Mexico include:

Owls
Barn owls (Tyto alba) are commonly found in abandoned mines in the southern part of New Mexico. A mine shaft provides a relatively safe nesting location difficult for predators to access. The AML Program preserves existing barn owl habitat when feasible.

Snakes
Rattlesnakes are a danger commonly associated with abandoned mines in New Mexico.. Rattlesnakes can sometimes be found near the entrance to a mine adit, going in and out of the mine depending on their temperature preference.

Other
Some other species that find temporary homes in abandoned mines include ringtails (Bassariscus astutus) and javelina (Tayassu tajacu).