David G. Mikesic and Carol Chambers
Once upon a time, a spotted bat poked its head into a crack in the wall of a limestone cave. He become hopelessly stuck and died there. Ten thousand years later, in 1994, two cavers in northern Arizona came upon the bat’s remains, still stuck in the crack. The cave’s still, dry air had mummified the body, which was easily identified by its unique coloration – large pink ears and striking black-and-white fur.
But, with only two exceptions, modern spotted bats were not known to roost in caves. They prefer cracks and crevices in vertical rock faces. The remarkable discovery of the Arizona mummy is changing that and other assumptions about spotted-bat behavior. More surprises are likely.
Scientists from the Arizona Game and Fish Department, Northern Arizona University and the Navajo Nation Department of Fish and Wildlife later accompanied the cavers back into the cave to search for any other mummified bats and to determine their ages.
We eventually found the mummified remains of seven spotted bats, along with a few individuals of other local species. All were on the cave floor and in various stages of decomposition. The original mummy was scientifically dated to about to 10,400 years ago. The others ranged from 2,100 to 300 years old. This range of ages strongly suggests a remarkable conclusion: Spotted bats have probably been using this cave more or less continuously for 10,000 years.
We also confirmed the surprising hints that modern spotted bats do indeed use caves. We set mist nets at the cave several times from 1995 to 1997 and documented the presence of six to nine spotted bats. They were roosting in the cave’s fissured and fragmented limestone ceiling.
Our research resumed in 2003, after a hiatus of several years, with a grant from Northern Arizona University. We netted and radio-tagged four male spotted bats as they emerged from the cave.
Our results are still being analyzed, but one intriguing discovery already has emerged. Spotted bats from the cave routinely covered about 50 miles to forage each night. These are small animals with a wingspan about the same as an American robin’s. Traveling such a distance at speeds of up to 30 miles per hour is quite a feat!
DAVID G. MIKESIC is a zoologist with the Navajo Nation Department of Fish and Wildlife’s Natural Heritage Program in Window Rock, Arizona. CAROL CHAMBERS is Associate Professor of Wildlife Ecology at the Northern Arizona University School of Forestry in Flagstaff.