Barry Keller, Curator of the Mammal Collection at the Idaho Museum of Natural History, has been conducting research on the bats of Idaho since 1986. In the last several years, he has been completing an inventory of bats using abandoned or inactive mines as potential habitat in northern Idaho. The core of his work has emphasized: 1) assessment of mine sites containing open adits that could serve as summer roosting or winter hibernal sites for bats, 2) assessment of the species using these mines, and 3) characterization of the thermal envelop inside selected mines and natural lava tube caves such as those found in northern Idaho and at Craters of the Moon National Monument.
In the northern portion of our state, the Idaho Panhandle National Forests have developed an aggressive model program of bat-friendly mine closures, especially at sites adjacent to Lake Pend Oreille. Such closures are known to stabilize what appears to be a general decline of the number of bats found in all the states that surround Idaho. Both the Idaho Panhandle National Forests and the Bureau of Land Management have also issued written closure regulations that permit prosecution of individuals entering old workings without a special permit and appropriate training.
Federal Lands in Northern Idaho contain an estimated 2000 inactive or abandoned mine sites, many with open portals. Human intrusion into these mines, whether motivated by curiosity or historical interest, subjects individuals to a variety of hazards that can prove life threatening. Hazards may include rotted support structures, unmarked or hidden vertical openings to lower levels of the mine, deadly gases, lack of oxygen, old explosives, and toxic chemicals. Consequently, inventory and closure of inactive and abandoned mines has received increased emphasis. Bats, many of which traditionally use caves and old-growth forests to roost and hibernate, may have become dependent on these old mines. Recent colonization of mines during the past century could be the result of an expansion of bat habitat through population processes enhancing dispersal, or bats may have been displaced from their native habitat into mines as alternative roosting sites. Additionally, some species likely enter mines to feed on insects or drink water accumulating near the portal. Irrespective of the factors that have caused mine use, the loss of mine habitat through closures may threaten a number of bat species that now appear to be mine obligates. One of these species, Townsend's big-eared bat (Corynorhinus townsendii), is generally considered the most sensitive species occupying mines in Idaho. Keller believes that this species may be using other habitats in forested areas, so a few individuals have been fitted with a miniature transmitter to permit relocation during a recent study. As a conservation measure, mines known to support this species have also been gated at the portal to permit bat entrance but prevent human disturbance of roosting or hibernating individuals. Additionally, mine shafts have been made accessible to bats only. Unfortunately, some individuals refuse to respect the importance of harmless, biologically important species of bats and attempt to violate closure systems, often to gain access to mines for recreational activities.
Studying bats is a time-intensive and expensive task as a result of equipment and travel costs. Individual bats may be captured using a special device called a harp trap or a net. The species shown in the net in this picture is a spotted bat (Euderma maculatum), a very rare, extraordinarily beautiful species that occurs in southwestern Idaho. Individuals of a species can be identified by attaching a band to the forearm as shown on this western small-footed Myotis (Myotis cilliolabrum). However, most biologists studying bats do not mark bats with bands unless required to do so to collect special information.
Scientific research is conducted to develop information needed to help conserve species that hold important professions in the economy of nature. If you would like to help fund bat research, the Idaho Museum of Natural History has an endowment fund that specifically supports research on mammals. Contributions to this fund are tax deductible. More information can be obtained by writing Dr. Keller, Director of the Carron Memorial Endowment, Box 8096, Pocatello, ID 83209, or by e-mail at Idobats@AOL.com .
