Dear WW: There are some wonderful bat sites on Internet. If you have a carpenter in the
family, you might enjoy making some bat houses, that might even help you escape risk
of West Nile virus. I never got around to it, and always regretted it. I built a couple owl
houses, but the owls never signed the lease.

Here's a URL aboutecho-location:
http://www.life.umd.edu/faculty/wilkinson/BSCI338/L25echolocation/sld025.htm