The unwitting subject of many a myth, bats occur throughout a wide variety of North American habitats. Idaho's 14 bat species include the silver-haired bat, hoary bat, fringed myotis, big brown bat, Yuma myotis, western pipistrelle, long-legged myotis, California myotis, long-eared myotis, pallid bat, western small-footed myotis, spotted bat, little brown myotis and Townsend's big-eared bat.

With the exception of the big brown bat, all of Idaho's species are considered to be state-sensitive species or species of special concern by Idaho's Department of Fish and Game. Townsend's big-eared bats have been petitioned for TES listing throughout the United States.

All Idaho bat species are insectivorous and provide valuable, natural pest control for agricultural crops, rangelands, forests and our own backyards. A little brown myotis can consume up to 1,200 insects per hour. A nursing mother bat will consume more than her body weight in a single night -- up to 4,500 insects such as mosquitoes.

A population of 150 big brown bats can consume enough cucumber beetles in a summer to protect farmer's crops from more than 33 million of the beetle's larvae. Loss of bats destabilizes ecosystems and economies, and increases man's reliance on chemical alternatives -- an additional threat to ecosystems as well as human health.

A spotted bat, one of Idaho's rarest species, was documented at WWP's Greenfire Ranch on May 11 by the author. Spotted bats typically roost alone, but may hibernate in small clusters. Spotted bats are believed to maintain exclusive foraging areas ranging from three to six miles from their day roost site from approximately an hour after sunset to an hour before sunrise. Spotted bats prey primarily on noctuid moths. Females produce a single pup early to mid-summer.

Overall distribution of bats is based on the availability of quality foraging and roosting habitat. A loss of natural roost sites has occurred throughout the U.S. due to harvest of large-diameter and cavity-containing trees, commercial and recreational use of natural caves, surface mining and the flooding of natural cave sites by large water impoundments. Foraging habitats have been severely threatened by wildfire, prescribed fire, human development, domestic livestock grazing and the overall conversion of native plant communities to exotic species and noxious weeds. A loss of native plant communities results in losses of the native insect prey base not only for bats but also for many birds and other wildlife species. More than half of North Americas 54 bat species are now threatened or in severe decline.

Bats have few behavioral defenses against predation or disturbances. Natural predation of bats is mostly limited to owls, snakes and occasionally other bats. The most devastating predation or loss of bats is directly due to humans and their activities, including the introduction of house cats and rats into native habitats.

Species such as the Townsend's big-eared bat often form large groups in caves or mines during either the maternity or the winter hibernation season. Entire populations can be killed by thoughtless vandals or entombed through improper closure of abandoned mines or other facilities. Disturbance during hibernation can also lead to starvation (due to energy loss), while disturbances during the maternity season can lead to the abandonment of flightless young. Bats tend to have very low reproductive rates; in most species, females do not reproduce until two years of age and in many instances only one pup is born per year to a reproducing female. Once bats are subjected to disturbances of the reproductive cycle, populations can take many years to recover.

Miriam Austin is a WWP field monitor and resource specialist.