Tuesday, January 25, 2005

Going batty


Bat (Myotis) eating a grasshopper

As a mammalogist, I feel compelled to touch on bats now and then. There are around 1,000 species of bats, out of 5,000 mammal species (only rodents are more diverse).

We had a little visit at TfK's offices by a little brown bat, Myotis lucifugus. They sleep in buildings through the winter, but on warm days they wake up a little and get lost inside. My officemate has a thing for bats, so she caught this one and waited for a nice day to let it go. While it was around, she fed it grasshoppers caught just for that purpose.

Every day, out comes the bat and a thawed grasshopper, and after a couple seconds, the bat found the food, and there was about half an hour of crunching. His plan seemed to be to smoosh the exoskeleton, suck up the juices, and then swallow the outside and move on. He had trouble with legs, and wings are clearly of no nutritional value. When the crunching stopped, he went back in his comfy bag, and things quieted down.

For the record, the incidence of rabies in bats is lower than in many other species of mammals. Worry about skunks and raccoons before you sweat bats. After all, bats would rather chew up a moth, a mosquito, or even a grasshopper than give rabies to a person.

Smart people who like using their yards encourage bats to eat there by putting up bat houses. You can buy them and install them, or build them yourself.

If you don't like having bats around, but don't mind seeing them, check out Flying Fur.

Unfortunately, bats have a problem. I bookmarked this story a while ago, but an NPR story (and our little guest) reminded me to post it.

Researchers Alarmed by Bat Deaths From Wind Turbines:

Thousands of bats have died at Backbone and on another nearby wind farm in Meyersdale, Pa. -- more per turbine than at any other wind facility in the world, according to researchers' estimates. The deaths are raising concerns about the impact of hundreds more turbines planned in the East, including some in western Maryland, as the wind industry steps up expansion beyond its traditional areas in the West and Great Plains.

That's right, wind turbines are chewing up bats. Some chiropterologists have put together the state of knowledge on the problem. One key finding is that deaths are most common in wooded areas. Open farmland or grassland is relatively safe. Turbines that aren't spinning are safe. Exactly what's happening isn't clear, but those facts suggest it's a problem of navigating around the blades when there is some distortion in the echoes from surrounding trees. Bats echolocate, so if the blades are spinning fast enough that the bat can't anticipate where they'll be, the bat is in danger of getting hit. When there are lots of things for the sound to bounce off of, it might make it too hard for them to pick out the spinning blades. That's just rank speculation, though.

If we assume a mystical power, maybe bats are designed to be killed by wind turbines. Maybe we haven't exposed an instance where an evolutionary adaptation isn't vulnerable to novel situations. Maybe all my scientific theorizing is worthless.

Mystery Wind” by Richard Thompson from the album Rumor and Sigh (1998, 4:35).