| Endangered Gray Bat - A Unique Mammal By Vicki Hatfield President; Grand Lake Audubon Society "Vickibird’s Voice"; Grand Lake Audubon Newsletter; June 2007 A recent speaker at our Audubon meeting mentioned bats as one of the mammals which lives in Oklahoma. He specifically talked about the gray bat, Myotis grisescens, which can be found in our part of Oklahoma, the northeast corner. Since gray bats are known to forage over large streams and reservoirs that fits with our streams converging and being dammed to create large lakes in Ottawa, Delaware and Adair Counties. Since those bats live within 1.2 miles of these bodies of water (summering caves), we who live here on Grand Lake O’ the Cherokees could have gray bats in our backyards and never know it. They appear only at dusk to feed during the night when we are rarely out and about. This bat is a small, insect-eating mammal which lives in cave colonies numbering in many thousands at times. The insects are trapped with wing or tail membranes whereupon the bat reaches down to take it into its mouth. Small teeth but weak jaws allow the insects to be ground up into suitable consistency for swallowing. The summering and wintering ranges are generally 10 miles apart, the summering caves as I said, being close to water. The wintering caves are entered early fall when insemination of the female occurs. Throughout the winter into the summer months she carries her unborn pup. He pops into the world in June—in the summer caves to be fed the aquatic insects adults gather. (notably mayflies). It is interesting how population numbers are computed. One cannot stand within a cave and count bats. What if there were 300,000 in there? The same situation exists for groups flying overhead. Impossible! But knowing about digestive process for one bat allows measurement of accumulation of bat guano on cave floors and the number of bats is then computed from that measurement. Another determination of whether caves are inhabited by maternal-only colonies, or males and non-reproductive females is made by the number of dead bats found on the floor near the entrances of the caves. Then humans need not go in and disturb the colonies to make that determination. Human disturbance is the primary reason for this particular bats’ endangered designation. A good example of how that happens is in the Hambrick Cave in Alabama-which sheltered a colony of 250,000 gray bats. In 1973 they all vanished!!! Visitors had built fires in the cave entrance, suffocating many of the bats. Fourth of July celebrators exploded fireworks inside, killing those remaining. Now a large organization owns the cave. The entrance is covered, leaving a small bat entrance and numbers of bats since that time have been counted at 300,000. In our Oklahoma corner there are approximately 22 entrances to bat caves which are gated with horizontal angle iron bars. Five of these contain gray bats. These iron gates are placed in the ‘dark zones’ of a cave passage, not at an immediate outside entrance to the cave. Bats don’t need to ‘see’ the spaces between the bars to enter. They use their “echolocation system”, which also finds the insects they eat. Gates can affect temperature of the cave and general climate which must be just-so for bats. They also induce increased swarming activity which risks unwanted predation by enemies. But in the grand scheme of things, human disturbance is so much more endangering that the gates which exclude humans and allow bats entry are a great idea. Extinction cannot be what we wish for one of the mammals of Oklahoma. Rather conservation of such a resource is our responsibility. We must have reverence for life, all life down to the tiniest ant. |
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| Endangered Gray Bats - A Unique Mammal |
| "As long as I live, I'll hear waterfalls and birds and winds sing. I'll interpret the rocks, learn the language of flood, storm, and the avalanche. I'll acquaint myself with the glaciers and wild gardens, and get as near the heart of the world as I can." John Muir |
| Endangered Gray Bat Habitat Range The range of the endangered gray bat is concentrated in the cave regions of Arkansas, Missouri, Kentucky, Tennessee, and Alabama, with occasional colonies and individuals found in adjacent states. The species' present total population is estimated to number over 1,500,000; however, about 95 percent hibernate in only eight caves - two in Tennessee, three in Missouri, and one each in Kentucky, Alabama, and Arkansas. Although gray bat numbers are still relatively high, their total population has decreased significantly during recent years. (Range map by USFWS) |
| Gray Bat (Photo by Merlin Tuttle) Bat Conservation International |
| Ament Cave Cookeville, TN Home of a Gray Bat colony (Photo by USFWS) |
| Indian Nations Audubon Society Eastern Oklahoma Muskogee, Tahlequah, Wagoner Fort Gibson & Tenkiller Lakes |
