Advice for hanging a bat box?

I'd like to hang up a bat box, wondering if you can offer some advice. Seems they're typically constructed of pine or cedar, while some are natural and others are stained. Some even have vent holes cut into the side. Is one or two chambers more bat friendly? And is it even necessary? I've consistently seen bats flying around the yard at dusk for years. Would there even be any benefit to putting one up?

Thanks for your question!

I’m glad to hear that you’ve spotted bats in your yard. They’re probably sheltering and roosting in natural spaces (such as underneath loose tree bark), or possibly unnoticed in human-made spaces (like this Big Brown Bat that snuggled into an overhang at The West Woods).

[Big Brown Bat at The West Woods Nature Center]

[Bat colony at Union Chapel in Newbury]

[Bat box on Tare Creek covered bridge]

• Material: Any kind of wood is just fine. Pine, cedar, plywood, hardwood — our bats aren’t picky! The only material to avoid is the plastic or fabric lining included in some manufactured bat houses; it can lead to tangles and sanitation problems.
• Size: The larger the better! The folks at the Ohio Bat Working Group have found that bat houses that are at least 17 inches by 20 inches led to larger bat house populations.
• Chambers: Similarly, the more chambers you can provide your bats, the happier they’ll be. Larger houses and more chambers give bats the chance to move to wherever within the house the temperature is to their liking. A cozy bat chamber should be about 3/4 inch to give the bats room, but not invite other animals.
• Vents: Vents in the side aren’t necessary in Ohio bat houses; here, the focus is much more on keeping the interior of the bat house warm and draft-free. (Most bat chambers feature a slot in the front to help bats detect the empty cavity within. This can be a simple gap between boards, or, in the case of these student-built bat houses at Ohio University, something fancier!)
• Color: Our chilly climate means that bats prefer a dark-colored house placed in plenty of sunshine.

If you’re looking for more bat-house tips, this handy video from the Ohio Bat Working Group summarizes the tips, tricks and best-practices hit upon for Ohio bat boxes.

Best of luck to you with your bat house! Let us know if any bats move in!

(Oh, and hey: here’s to a happy Ohio Bat Week later this month!)

-Naturalist Chris Mentrek