An interesting post on bats and habitat, and why sometimes bat houses will or won’t attract occupants. Taken form the Bluebird Monitors Forum, and published with permission, by: Tina Mitchell in CO.

“Hi, list folks–

I really appreciate bats–at least the bats we have here out west.  (I know a few vampire bats have been found crossing from the Mexican border.  They make me a tad nervous, but mostly because I don’t know much about them, I suppose.)

A number of years ago, when we could still rehab bats here in Colorado, I did a week-long “boot camp” on bat rehabilitation and rearing at Bat World Sanctuary in TX.  (Bats have been officially declared a rabies-vector species in CO.  This means, in our state, that no one is allowed to rehab them now unless everyone on the premises has had the pre-exposure series of rabies vaccinations.  Our rehab center can’t mandate that, since we have so many volunteers.  So we no longer rehab bats, I’m sorry to say.  The ones I’ve helped with were fascinating, gentle, intelligent-seeming creatures.  Individual in-home rehabbers are the only hope left for for injured, ill, and orphaned bats in this state.)

What I recall, from a deep, dusty memory of the Bat World training, is that most bat houses that are used serve as nursery colonies–groups of mothers and their pups.  It’s certainly possible that bats in the east act differently.  And a one-week training years ago hardly makes me a bat expert.  The most common bat species we have here is the little brown myotis.  Aside from nursing colonies, these bats tend to roost during the day singly, in rock crevices, under loose bark, and wood piles.  Single bats will occasionally roost in or around buildings, but it’s not their most common choice here.

So a bat house–unless you’re within 1/4-mile or so of water, where nursing colonies tend to be–doesn’t get any bats.   We certainly tried on our property, before I knew this.  Repeatedly.  Even though we see these marvelous insectivores in decent numbers at night.  But, as I said, perhaps they behave differently in areas other than arid pinyon/juniper habitat out west and will use houses as daytime roosts elsewhere.

An interesting overview article about White-nose Syndrome (WNS) appeared recently in Microbe.  Don’t be fooled by the title of the journal–it’s a very readable article.  Toward the end of the article, the authors mention that WNS has existed in bats in Europe for quite a while.  Yet those populations have not experienced elevated mortality rates.  That sounds like a promising line of research for some wildlife researchers.  We surely need some hope for these valuable mammals.”