Bat House Forum

[William Bagwell]

Working on a seven chamber bat house with very thin baffles. Will be quite
a contrast from the four chamber with 1" thick poplar baffles I built
last summer. Thinking of sealing the top of two chambers since this one
will lack thermal mass and it might be years before the bats are numerous
enough to provide their own. Had four bats plus pups most of the summer
2010 and seven plus pups for a much briefer time summer of 2011. Going to
put this bat house (and a more traditional five chamber design) up as
close to where the bats were roosting as possible. Which oddly is the
north east corner of our house.

Which two chambers should I seal off? Or should I block three, leaving
four open to the attic?

Frank's cedar three chamber,
new-bat-house-for-pups-t953.html
blocked the back two.

JR0835's new nine chamber,
new-bathouse-t1231.html
seals off the center three.

As to the attic its self, due to my 'half' sheet of material being a bit
small 48" X 42" rather than the expected 48 X 48 (got a nice discount...)
my baffles are 3" shorter than they should be for a house this size.
Should I shrink the attic by 3" to make up for this? Have some closed
cell plastic foam that I can stuff in the top. Believe it is either
polyethylene or possibly polypropylene foam based on how slick it is.
(not foam rubber) This will still leave enough room for the bats to move
from one (open topped) chamber to another without going to the bottom of
the bat house.

Pictures coming soon... Oh, this is a 100% plastic box, no wood

[cloudman75]

William,
I will not be providing any more attics as there is no way to remove droppings or wasp nest unless perhaps taking the house down to do it. I had a couple of bats that would go into the attic when I shined a light up in the bat house, but in general I was not pleased with the results. As for which baffles to stop up at the top I just used the back two for convenience without thought. I believe the 9 chamber builder said he chose his chambers toward the center so they would be warmer. As I had often posted, my bat houses get too hot and even the young pups a couple of weeks old sometimes come down on the landing to get air and cool off a little. Hope comments from others will help you decide what to do on yours. BTW, I have no bats right now. Looking forward to your photos.

Frank

[William Bagwell]

So no true attic, or space at all, above the 2-3 sealed off maternity chambers. Sounds like a plan to me. Now that I think about it I remember this being discussed before, probably as a wasp deterrent.

Just to clarify, a small gap at the top of all the other baffles is still OK? As narrow as these baffles are nothing much is going to stay on the top edge. If I don't leave a gap then these baffles will all have to have holes drilled to allow the bats upper level movement between chambers.

William

[cloudman75]

I think some do provide a space above the baffles. I always put a ceiling there between the top of the baffles and the exterior roof to retain the heat in my mind. I either left space above the baffles or cut a notch or hole in the baffles for the pups to travel back and forth without going down to the landing board area. I don't know how much the pups use the feature but have seen them in various chambers.
I am going to refurbish my big 5 chamber nursery and put it back close to where it was on a pole. It was not used at all last year propped up against a tree even though the limbs were trimed off the tree and the house was on a pipe.

Frank

[Terry Lobdell]

Years ago people would leave the tops open above the baffles to allow bats to move among different crevices internally. However, many including Kent Borcherding found that open ceilings fill up quicker with wasp nests.

I prefer to have the tops of each crevice sealed off so that each crevice has a different temperature........

I have definitely found that bats love to go back and forth between crevices internally using either notches in the sides of the baffles or holes drilled.....I have many boxes here at home where I can easily watch them go back and forth.....Using one inch boards makes it easy to create internal access by just leaving a gap. When I have used plywood for baffles I have both drilled holes and notched the sides........another good thing about these internal access openings is they can allow ventilation movement between baffles if they are positioned the right way.......

The most recent large designs I constructed, I have made them 4 crevices using one inch boards for baffles. I leave one or two gaps in the lower third of each baffle for internal movement by the bats.........I try to gradually locate each baffle gap slightly higher going towards the back of the box so that air moves from front to back.........not only does this get ventilation moving towards the back more, but it helps cool the back crevices more in case there are big browns roosting.

For the actual back of the box I use full 2"X4" with each one gapped about 5/8". Only the very top 2X4 is tight to the ceiling. This type of ventilation is what big browns need in very hot weather. The 2 inch wood is also great during the mounting process because of how the extra thickness holds screws better. A design like this works very well for both big and little browns.........

[IowaNate]

I now put 1.5" diameter holes in my baffles in the middle about 1/3 to 1/2 the way up. But I keep the tops of the baffles tight to the roof.

[Emersombiguns]

I read with interest what Terry is doing. Both of my house's have loaded up with bats.They both have the baffles all the way up to the roof. However, both also have some 2 1/2" holes in each baffle in different places to let the bats move between baffles inside the house. . I did notice in last 2 years the pups were in the middle baffle(5 total) in most cases. I am in La and last year we were in the 100's many days and had one of the worst droughts in years. My house's are painted black and I think brown would be a better color. The only thing I can say is that my house are blocked by late afternoon sun, but have direct morning sun. They have stayed this winter in some cold weather. I think I would not make the attic like Frank said. I have had NO wasp's what so ever in my houses. I did not even tilt them down this winter for cleaning.. I do think the multi chamber design is what you want..Randy

[William Bagwell]

Randy, the all plastic bat house ended up being separate chambers with no attic. Both of mine with wooden baffles have gaps at the top. Might should have been the other way around...

[cloudman75]

William I had 6 bat houses up last year very close to each other. All had gaps at the top with the exception of one with an attic. The only one with wasps plus a dirt dobbers nest was the one with an attic. In the several years before last year I never had a wasp nest built in the chambers. That is pretty good evidence to me that wasps are attracted to attics in bat houses. The house with the attic had holes in the baffles to allow travel between the chambers with the attic ceilings installed. I could let the bat house down and rake the wasp nest out with a bent stiff wire, but the same post also supports two other houses. That makes it no option for me to clean the attic. There have been some bats using the attic along side the large wasp nest this winter. I suspect the wasps would injure or kill a pup that contacted them so I have decided not to use another one. I also have taken photos of several wasps that seem to have
spent the winter in the house but they seem to get along OK with adult bats. The pups are my main concern.
This year I removed one bat house as the baffles had mesh which had come loose from the baffles. The baffles are held in as a unit with screws and next year or maybe later this year I will replce them with rough board cedar baffles and re hang the bat house on my amateur radio tower to see what happens.
I think your gaps at the top will work out fine in your bat house.
BTW, I just checked with a light at 8:45 Feb. 29 there are 6 tiny little bats that look similar to little browns and one small dark black looking bat using three different houses. The tiny black colored bat is in the house with an attic but not in the attic yet. It is very warm right now 65 degrees on the thermometer.
We are scheduled for stormy weather tonight. I am glad to see some bats and looking forward to warmer weather and more bats coming in. Update at midnight I counted 8 total. Also the bad storm may have bypassed us here. Frank