I just spent the weekend studying bats in the field with Dr. Michael Baker. Dr. Baker is investigating the preferred habitat of the long-legged bat (Myotis volans). These bats roost in dead trees and rock crevices during the summer, and if we understand what kinds of trees the bats use, foresters can minimize the negative impact logging might have on the bats. Besides being weird and wonderful creatures with incredible adaptations for flight and echolocation, bats are important to conserve because of all the insects they eat. I joined Dr. Baker in the southern Cascades, near Bly (in the state of Oregon?).
The ecosystem was dry, rocky, and rugged, like much of the American West, with sparsely spaced ponderosa pine at higher elevations and cattle grazing amongst the sagebrush in the valleys. In the evening, we set up mist nets around a small pond. When bats come to the water to drink, they can’t detect the fine mesh and get caught in it. We waited nearby, so no bat had to struggle in the net for more than a few minutes. Although we were primarily interested in M. volans, we trapped, weighed, and measured several other bat species, including the Western long-eared bat (Myotis evotis) and the little brown bat (Myotis lucifugus). I wore gloves, since I haven’t had my rabies shots (although the chance of finding a rabid bat was extremely small), and the frightened bats chomped into the leather with their tiny teeth. They had soft, fluffy fur, beady black eyes, enormous ears for their size, and miniscule pink mouths that emitted anxious chirps. We kept the bats in little cloth bags while they waited to be processed, and then every bat was released after only a few minutes of handling. Well, every bat except one. One lucky female got a miniature radio transmitter, complete with an antenna, glued to her back. That procedure took a little longer, but then she, too, was set free.
The next day, we tried to track her down. Dr. Baker wanted to find where she slept, which would probably be a roost with several bats. We drove around on forest roads for a couple of hours, listening on our receivers for the signal she was transmitting. My arm was beginning to ache from holding the antenna out the window of the truck (later, I would notice a mild sunburn on only my right arm). Finally, we heard the machine beep. Moving the antenna could tell us the general direction the signal was coming from, and we set off into the woods on foot. Unfortunately, the terrain was rough and we weren’t able to locate the roost before the batteries on the receiver died. The transmitter batteries should last a few weeks, though, so Dr. Baker will have many days to identify the bat’s roost(s).
We know so many fascinating things about these bats, and yet there is so much we don’t know. Presumably they hibernate somewhere in the winter, maybe a cave, but no one knows where. When a roost accumulates too many parasites, a large group of bats will abandon it one evening and all meet up in a different tree the next morning. How do they communicate this to each other? Furthermore, small active mammals usually burn themselves out metabolically in a short time, yet somehow these bats can live for decades. How? Why? There is much more to learn.