Looks as if my explanation the other day for the high level of daytime excitement by the bats was both too pat and too optimistic.
It turns out that the individual whom I could see so clearly on the landing area of the bat house was not so much protective as in need of protection — this bat was injured and subsequently died.
Looking up the next morning, I saw this:
Not good. I carefully removed the poor thing’s body from the landing area (with a stick and gloves) and took a couple of pictures before burial.
Here’s one closeup (color-enhanced):
We’re looking at the deceased bat’s back. The folded wings end at the top with a claw (a vestigial thumb?) used for climbing around in the bat house, and you can clearly see a foot with tiny claws at the bottom of the picture. This unfortunate individual is about four inches long.
I’m sure that there is substantial mortality among bats, like any wild species, but in the three years or so that I’ve been paying attention to the bats in my bat house, I had never actually seen a sick or injured bat. And since White Nose Syndrome is killing many bats in the Northeast, I was really concerned about what might have caused this bat to die.
Fortunately, the expert folks at the Florida Bat Conservancy were kind enough to look at my pictures and answer my concerned e-mail. Assistant Director Jennifer Smith writes, in part:
As of now you shouldn’t be concerned. From the picture it looked like the bat had a broken wing and couldn’t fly out each night to forage for insects. The bat’s wing bones are very fragile and can break easily. Due to the bat’s high metabolism, it doesn’t take long for a bat to starve to death. The wound site might have been infected as well. …
White Nose Syndrome hasn’t spread this far south. It started off in New England and has spread farther down through Pennsylvania and West Virginia. So far it’s affecting the cave dwelling bats and scientists are still trying to figure what is actually causing it. They are starting to link it to pesticide use on agricultural lands. We hope that it never reaches us!
I was relieved. Jennifer’s observation about the broken wing fit with what I had observed the day before the bat perished, when he or she was carrying on in daylight outside the bat house. The bat I saw that day was flexing one wing while vocalizing, and now it seems that may have been because the other wing was injured. Sad, but not as sad as if we had a virulent bat disease like White Nose Syndrome to worry about — yet.
So far, all the remaining bats (about 25 as of my last visual count) seem fine.