Bat House Forum

[GFox]

I would like input from anyone on if and how to design the bat house I envision.

What I currently have: A 13 foot steel pole has a steel plate 5.5 in. x 7 in. welded on top. Lagged to the plate is a block of wood 5.5x7x24 in. On each of the 5.5 inch sides of the block, I have a 10 inch PVC Bat Can nursery house. They attach with angle iron brackets and lag screws. These are oriented SE and NW. That leaves about 12 inches between the PVC houses on the other two sides of the wood block available for houses.

What I am considering: I was thinking of building a house somewhat in the shape of an inverted ‘U’ to slip down over the top of the wood block which would face NE and SW. In general, these would be a traditional 2 or 3 chamber box on either side about 12 inches wide and 24 inches tall (not unlike the box on the index page of this forum). The part I would like input for is if/how to connect the two boxes across the top of the wood block (an attic of sorts) so bats could move from one box to the other depending on heat conditions.

Would this be too drafty? I don’t think I would want them to roost in this ‘attic’ because it would not be accessible for cleaning? How much headroom should be in the attic? Pitched roof or flat? Should I provide screen in there or can they just crawl from one side to the other on the attic floor (5.5x7)? Should I just build a traditional box for each free side and forget the cross-over?

Gary

[Terry Lobdell]

Gary, the top cross-over is a very interesting idea and one I would definitely pursue. Myself, I would probably make the cross-over section slanted, maybe 45 degrees. I don't think mesh would be neccessary. Two inch wood might be good for some thermal storage. I might consider building this design in 3 pieces for ease of mounting. A detachable roof/cross-over section could be designed for easy clean out as well. Ease of clean out may be neccessary not only for guano but possible wasp nests too. The bats will probably roost in the attic during cool weather because that is where most of the heat will be. I might consider insulating the the roof also. But that depends on which part of the country you live in. I live in NWPA and we often get cool rainy weather in June when pups are first born.

How many crevices will the 2 boxes on each side have?

[GFox]

Terry,

I live west of Baltimore, not nearly as cold as your area. I too had a concern for wasps and guano which is why I was thinking of a smaller low-height cross-over (no vertical room for roosting and perhaps a screen ceiling so wasps wouldn’t attach). Didn’t you design a framework of passages connecting multiple boxes? Was that successful and what were the dimensions of the passageway? Getting up there means erecting scaffolding. I really like your idea for a removable roof/cross-over so besides cleaning, I could convert to two standard boxes if this doesn’t work out. How would you suggest it be made as airtight as possible? Do I plan on a re-caulk each time or would a good foam weather-striping work? I was thinking 2 chambers on each side to minimize size and weight. Bachelor roosts for the next door nurseries. Thanks for the reply.

[Terry Lobdell]

Gary, if you take a look at my mounting board pictures you can see how all bat houses on the structure are accessible. It has been successful and is the only structure I have had both my little brown and big brown maternities roost in.

There are many ways to design access to different bat houses mounted on one pole or on a building. What I like about your idea is the fact the top cross-over will act as heat storage.

I would consider at least 3 crevices in each of your boxes. Little browns strongly prefer multiple crevice houses.

A foam gasket top may be the way to go. It could be bolted tight to each bat house for a tight seal.

From my experience, wasps can still attach to screen. A removable top/roof may be the easiest way to remove nests.