Bat house

When a neighbor complained on social media about swarms of gnats in the neighborhood, my wife suggested if they'd install a bat house they'd have fewer bugs. We got to thinking about it seriously, and after finding plans on line, we decided to give it a try. I found two places on our house that are high enough, facing the right directions, and with suitable places for guano to not be a problem. I talked with a local bat conservation person and we agreed that our location just two blocks from the river should be conducive to bats. I'd seen them flying around years ago, but haven't been out much at that time of night lately.

I have a southeast exposure on a chimney, which should be good for spring-summer roosting. And I have a southwest high wall which I'm told should be attractive for fall-winter roosting because of the extra sun. The plans provide for making two houses out of half-sheets of plywood and other lumber. The chimney space is little smaller than the plans call for, so I'll have to customize it, so I decided to make the southwest house first because it will be right according to the plans. And by now it's a little late to expect spring roosting - they've probably already had their babies. I used a medium gray paint from our eaves, so it will blend in with our house. The local person said that for a southwest exposure in our area that should be perfect - too dark and it will attract too much heat. Bats like it pretty warm inside for raising their young, but not too hot. The bat societies publish color guidelines for different parts of the country. Here's the first finished product.

So what makes it a bat house different from a bird house? Lots!

It's open on the bottom, with a "landing pad" that extends below the opening. They can land there and climb up.

It's mounted high on a wall so they can fly right to it, away from trees so predators can't get to it.

Narrow space inside. Bats like to roost in the space between bark and tree trunks. This one has four chambers, each just 3/4" front to back. They like it cozy! I made the dividers removable, in case it needs to be cleaned out sometime in the future. See the little rotating clips in the picture above? I designed and 3D-printed them.

It's dark, except near the air vents low on the front and sides, darker than the pic above makes it appear.

It's caulked all around the top to keep drafts out.

Rough texture inside so they can climb and cling. Here's a picture of one of the dividers. I ground horizontal grooves and left the plywood rough like bark. It's finished with stain, not paint, so it won't be smoothed over.

There are holes in the top so the bats can move between rooms if they want. The rooms facing the sun get warmer than the ones in the back.

To protect the roof, I cut a leftover shingle from our house and stapled it on.

I knew the house would be rather heavy to try to mount directly on the wall, so I used a method called a French cleat. I sawed a 2x4 at a 45 degree angle down the middle. A wedge-shaped piece mounts on the wall, and the matching wedge mounts to the house. Then I just need to lift the house up and drop it into the slot. The finished house probably weighs 15 pounds, enough to hold itself in place. But just in case of earthquakes or high winds, I installed latches on each end.

A couple of 2x4 blocks on the bottom finish off the back part. Having the house a couple inches out should help keep guano and urine from falling on the wall - I hope. I didn't use a solid board on the bottom so leaves and debris could fall out. Also, I don't want the space between the bat house and the wall to be too dark - sometimes bats will roost in that space too if it's too attractive.

Mounting it 12 feet up on the wall was... interesting. I installed a hook above and used a rope and pulley to hoist it up. As you can see, the color blends right in with the house except for the dark landing pad. It's only visible from the street from a narrow angle.

The rest is up to the bats! The local conservation person said that bats in our area have learned to look for gray boxes because the county (or someone) has installed several. So chances are good we'll have some residents someday.

I mentioned that I hadn't seen bats in a long time. Well... tonight I took some trash out to the curb as it was getting dark and spotted a BIG bat that flew right in front of our house and around that side of the house. So keep your fingers crossed for us!