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The bat should not have come as a surprise, given that the old house in Sonoma County had been uninhabited for a couple of decades. Some bats like to hang out in old houses. Still, we were startled when it bolted from its roost on the upper landing and flew a couple of circuits of the ceiling. It was a good-sized specimen of bathood, larger in the body than a mouse, with overall grayish fur, paler on the belly, and enormous ears. Eventually it took cover, but we found it tucked behind a beam with just its head and ears showing. We decided not to startle it again with the camera flash. 

The owners of the property said this was their first bat report, and we were later told that the creature left on its own. I’m fairly sure, based on relative ear size, that what we saw was a Townsend’s big-eared bat, common and widespread in California, although we had never met one. The other large-eared bats have distinctively patterned fur or unusual facial features. This one, bar the ears, had a standard bat face without any of the nose leaves, lappets, or other baroque accessories to which bats are prone. 

It was alone, although the species sometimes roosts in groups. There’s an abandoned house somewhere in Point Reyes National Seashore which is being preserved as a bat sanctuary, and I remember hearing that Townsend’s big-ears were among its residents. Not totally dependent on human-provided housing, they still roost in tree cavities as well. 

sPeople sometimes ask me if bats will actually use commercially available bat houses. I don’t have any data on this, but I suspect it’s a crapshoot. Social bats will probably prefer to roost where there’s room for lots of other bats. Some species, like the Mexican free-tailed bats, are attracted to Spanish tile roofs. The former business college across the street from the central library in Berkeley used to harbor a colony of free-tails; if you watched just at dusk you could see them emerging from the tiles and flying away.  

The classic bat house story is one I heard from a seaplane pilot in the Florida Keys in 1980. Decades before, after the railroad had been strung down the Keys but before a hurricane took it out, an Ohioan named Richter Perky bought some land on Sugarloaf Key and opened a hotel. It was a prime location except for the mosquitoes, which were abundant and voracious. The hotel didn’t get a lot of repeat business. 

Perky probably would have resorted to DDT had it been available then. Given his limited options, it occurred to him to try what would later be called integrated pest management. He had read that bats ate mosquitoes. Southern Florida has its own native bat species, like the handsome red-furred Seminole bat, but Perky wasn’t aware of that. Instead, he commissioned somebody to go to one of the western caves—maybe Carlsbad, maybe someplace in Texas—to capture a quantity of bats and ship them to Sugarloaf Key. 

Anticipating their arrival, Perky built a multi-compartmented structure, something like a dovecote crossed with a ziggurat, near his hotel to house them. When the great day came, he unpacked them—I seem to recall that they had been sedated for easier handling—and placed each one in its individual cubicle. Then he waited for darkness, when they would emerge and do their stuff. 

They emerged, all right. Calling on the homing instincts that serve bats so well in migration, they flew straight back to Texas (or New Mexico.) The hotel went under; Perky returned to Ohio. The bat tower is still standing, or at least was still standing in 1980. The locals call it “Perky’s Folly.”