Tuesday, September 28, 2010
A few weeks ago, I once again had the pleasure of spending time in a darkened forest with Merrill Tawse, along with a large group of other batters. Yes, batters, and not of the baseball variety. We were there to observe Merrill and crew mistnetting the little furry flyers, and if you ever get the chance to go on such an expedition, do it.
Note the band affixed to the bat's wing in the photo above. They aren't catching these things for the fun of it; Merrill has for years been banding bats, and the whole procedure works essentially as it does for birds, except it's done at night. In this case, they'd set up a series of large nets in - not by - the Clear Fork of the Mohican River near Mohican State Park. Bats love a good waterway - lots of flying insects to feed upon - and the number of bats patrolling this stream is astonishing.
We've spread the bat's wings, revealing the intricate handlike bone structure that supports the membranous tissue. It's amazing how small bats look up close and personal. Nonetheless, they've got sharp little needlelike teeth, and won't hesitate to use them on offending humanoids who pluck them from the skies, hence the handler's thick gloves.
Bats utilize echolocation to navigate, and it works quite well. Essentially, they emit a rapid series of clicks, which fire ahead of the animal and then bounce back off of whatever objects lie ahead. Sensitive receptors on the bat allow it to instantly triangulate on the object and determine other information about the structure, such as size, distance, and speed. So fine-tuned is bat echolocation that they easily pick up on small insects and effortless snap them from the blackened sky, in conditions where you or I would hardly see our hand in front of our face.
For the bander of bats, this mammalian sonar system means they're hard to catch. The bat may fly into the net once, but often not again. They detect the fine mesh screens and whoosh right over the top.
There are a dozen species of bats that occur in Ohio, and the Little Brown Bat in the first two photos is probably the most common. The one above is a Northern Long-eared Bat, Myotis septentrionalis. This Spocklike creature was caught by Merrill a few years back during an Ohio Ornithological Society field trip, and it turned out that Merrill had previously captured the beast - four years prior!
Bats live a long time. They're essentially furry Rip Van Winkles, and spend most of their time fast asleep. More than asleep, really; when a bat crashes, it enters a torpor and drops its bodily functions down to but a fraction of what their system would operate at when the animal is active. The upshot is that it takes bats a long time to use up their resources, and thus the little critters can live for decades - quite remarkable for such small animals.
Thanks go to Merrill Tawse for so freely sharing his expertise and enthusiasm, and exposing so many people to a side of the nightlife that they'd never otherwise get to see.