Bat House Forum

[cloudman75]

URL=http://img826.imageshack.us/i/1010672l

Uploaded with [url=http://imageshack.us]ImageShack.us[/url

Bats do not like drafts in their houses[b]True or False?This woodpecker hole is large enough to create a good draft at the top of the front chamber, yet the little browns seem to enjoy it. I see a freetail or two in there also.


Uploaded with ImageShack.us
Photos taken Oct 25, 2010 late afternoon

Frank

[po boy]

Great photos Cloudman,

I am in the process of building several bat houses for the Rome Ga. area and I think you are a little North of there,

Looks like you do not paint/stain the exterior of your houses and the cedar will age to a lite color. Is that correct?

Any suggestion on exterior colors for the Rome area?

I do enjoy your posts.

[cloudman75]

Hello,
I am southeast of you in metro Atlanta-Lithia Springs a few miles west of six Flags off I-20. I did not paint or stain the house in the photo as it was purchased from OBC as my first bat house. They did not recommend paint and I must admit the bats love this little house. The two I just built are cedar so I did not paint them, only the pine parts were painted.My other two houses are painted with three coats of blue latex.
One is a light blue, the winter house is dark blue on top, light blue on bottom. I have been to Rome many times and it does get hot there in summer. I would say a lighter color to suit your choice would do just fine. We don't need black here in Georgia. I know from experience that the freetails and little browns like blue and unpainted cedar. I have no other experience and it would be just speculation on my part to guess at what your bats would find attractive. I do know bats are not too hard to please with color, as they first chose my white trimmed louver
to live in on the end of my house painted white. In general my bats suffered from heat this season, not from lack of heat.
Glad you enjoy my posts, and welcome to batting. Bats need all the help they can get.


Frank

[IowaNate]

Frank, it seems to be an interesting question about airflow. My big browns still readily use the small three chamber I made even though the roof is becoming detached and creating multiple 1/8" gaps at the top. Granted, the house is still water tight given the overhang of the roof. Airflow might be an interesting factor that isn't readily tried since most research advises against it.

[cloudman75]

Nate,
The large 3 chamber I just put up has a 1/4 gap at the front and back between the top boards and the roof. If you stand in front of it you can see through the house from front to back under the roof. I did this as an experiment to see if the bats will use it. I'll have to wait until next year when it gets hot to find out. I also put cracks about 1/2 inch wide in the front and back to give more ventilation. I will be anxious to see what happens. The baffles have gaps at the top plus holes down about mid way for lateral movement. One chamber is tight with a ceiling and calked for no draft and heat retention if they want it. As you probably have thought at times, what you read may not always apply in your own location. We get a lot of opinions from some who only spend a summer checking out bats. That's what makes it fun to me when I try something of my own opinion and the bats may agree and use it. It takes time and patience as I'm sure you know. If the bats don't like all the ventilation, I can take it down and make it tight with the removal of a few screws and some calk. I have my hollow pole and new bat house ready to put up, but the bats don't want to leave yet. I still have about 40 little browns and I guess at least 25 freetails here. No bats in my new three chamber yet, but at least they have the opportunity to look it over before they leave in Nov. My plan is to put a new house and an existing house on the hollow pole. Then I will lower the big three chamber and add the existing unventilated winter house to that pole. Each pole will then have a new house plus a house that the bats have used. I have also trimmed a large sweegum tree up for about 25 ft
which will be a south exposure. As soon as I make a french cleat, I will hoist up the 80 pound old 5 chamber and put it on the tree.
You can smell it 5 ft away so it may attract some of the bats next year. I'll have to go back and look at Terry's post to make sure I make the cleat right. I will have a total of 5 houses for bats next season.

Frank

[Dave Miller]

I would guess that bats prefer some ventilation if the air temp in the house is comfortable or "hot" (from the bats' perspective). If the air is "cold" I would guess they would like little or no ventilation. Just like us humans!

I would think that an ideal roost would have both a well-ventilated roost space and a well-insulated roost space, so the bats could move around to find a comfortable spot.

But we still have a lot to learn about bats so the more experimentation and careful observation we do, the better.

[garverm]

Regarding air flow observations, I have used both a wireless digital thermometer and an Infra-Red beam spot temperature reader to check some temperatures this summer. For reference, on a sunny day with direct sunshine, my uninsulated attic crawl space was 130 degrees. My dashboard in a mid-size car with black interior was 160 degrees. The shady side of an utility pole, three feet away from a reflective south end of my home was 110 degrees. The last reading was taken with the wireless thermometer in open air conditions, while the ambient air temperature was 90 degrees. On sunny days with an ambient air temperature of 68 degrees, the back side of the utility pole still could reach 90 degrees. I believe the sun's rays were bouncing off the wheat-colored vinyl siding, and also the white limestone gravel mulch, and affecting temperatures on the back of the utility pole. My conclusion is that temperature readings should be checked before making a statement like "all bat houses need air flow".

A secondary affect of temperature is that a 68 degree room in a home can feel comfortable in summer and cold in winter. My body temperature at roughly 98 degrees will lose heat faster in winter, as heat is wicked away from my home. To me, this indicates what many have reported that a bat house for Spring should be heavily insulated with minimal air flow. And, a bat house for summer should have ventilation and other methods for moderating heat build up.

[cloudman75]

I have come to the opinion that insulation for a bat house is not beneficial. Most information I have seen from those who supposed to be in the know based on research do not encourage insulation. Of course I have not seen it all for sure. It is just my opinion, and that is what forums are good for, to exchange ideas. An unused insulated house is cooler than an unused uninsulated south facing full sun exposed house. I am glad to see someone else has actuall taken measurements with a thermometer. I have used the remote sending unit of my remote wireless thermometer attached to a cpvc 1/2 inch pipe stuck up inside chambers of my three chamber bat house to compare ambient temps with chamber temps. I have found that at the top of the chamber temps run only 4 to 5 degrees above ambient. This I believe is due to the solar insolation(heat) being absorbed and transmitted to the chamber at a rate depending on the U factor of the bat house material exposed to the sun. If insulation is added, solar heat transmission is reduced or eliminated for the most part. Of course if the house were full of bats, then the bat house would be warmer if it were insulated. I don't think that it is worth my effort to come up with a way to measure the temperature of chambers full of bats. If they are full then, the bats have made the determination that it suits them. My present scheme gives the bats a spring house, a summer house, and a fall/winter house from which to chose. As for ventilation, I have supplied houses with less than what some have suggested, about what has been the norm, and none. In addition, I have built one house with at least twice the ventilation of so called normal. Next season will tell me which the bats prefer at those times I hope. As for infrared or laser thermometers, they just tell me surface temps so I don't use them to measure air temps in the chambers.
Hurry and get your bat house(s) up and keep the forum informed on how they are accepted. We can all learn something by exchanging information.

Frank

[Terry Lobdell]

My thoughts on this subject are based on experience here in NWPA.......

Little browns up here seem to do fine with little to no ventilation.....but I always try to build ventilation of some kind into all my bat boxes....

Big browns seem to absolutely require ventilation especially in humid weather........the humidity for them seems to be as much a factor as the heat......

On the subject of insulation, my big browns frequently use an insulated box early in the spring during cool temperatures so they can stay in torpor until it is warm enough for insects to be flying.........this particular box is oriented to the west and probably maintains an even cool temperature......

I have observed that a bat box that is starting to deteriorate and have flaws in the exterior will continue to be used by the bats simply because they are used to it and feel comfortable roosting in it.........much like how people will continue to be attached to a favorite possession even as it wears out........

[cloudman75]

Terry,
I have been thinking about trying an insulated house to attract Big Browns. After reading and thinking over some of the recent posts, yours, and others, I believe an insulated house for summer would have more stable temperatures and might attract some big browns to my place. They just don't show very often here. What type insulation did you use? I have room to mount another house on my radio tower pole and face it East or North. I can only think of a double walled exterior with insulation between as a way to build an insulated house. Any information from anyone who has built an insulated house would be appreciated. After rethinking some of my previous opinions, I think they may have been in error and I would like to put up an insulated house to see what the bats think. I also read about the Mayberry insulated houses in Texas which had some success back in 2002.

Frank

[Dave Miller]

Terry,
I have been thinking about trying an insulated house to attract Big Browns. After reading and thinking over some of the recent posts, yours, and others, I believe an insulated house for summer would have more stable temperatures and might attract some big browns to my place. They just don't show very often here. What type insulation did you use? I have room to mount another house on my radio tower pole and face it East or North. I can only think of a double walled exterior with insulation between as a way to build an insulated house. Any information from anyone who has built an insulated house would be appreciated. After rethinking some of my previous opinions, I think they may have been in error and I would like to put up an insulated house to see what the bats think. I also read about the Mayberry insulated houses in Texas which had some success back in 2002.

Frank

I put one piece of rigid insulation in the "attic nursery" of my houses (i.e. the bottom of the roof, with a slight gap between the roof and the insulation for venting). I don't have any data on whether the bats prefer (or even have visited) that space. But there is really no way to know if they are using it, short of very careful exit observations which I don't really have time to do. That space is really intended for a nursery colony and so far I think I've only had bachelors.

Some photos:

[cloudman75]

Thanks for info Dave and photos. I have seen that bat house of yours many times but not the details you posted this time.
Great photos you made. I have access to some free duct board used in hvac work, so I may build a house with the roof and about 12 inches of the upper half insulated. All will depend on my existing materials. I cannot have a house that is heavy as my pole won't support much more weight. I am also thinking of a very light and tight thin plywood house about 24" h and 12 inches W. three chambers.

You may find this site interesting. I could not navigate back to the 2002 article I read recently, but it was the same people. It had a comparison of insulated and uninsulated houses side by side.

http://icb.oxfordjournals.org/content/48/1/107.full

I did want to comment that I read your other post and freetail bats often fly at 10,000 ft and 60 mph so I have read on several sites,and also
that they do feed at those heights when food is available.

Frank

[Gary Springer]

You asked, True or False, bats dont like drafts.

False!!!!!!!!

Thank you for posting this photo!

I think many bat houses are not successful because they dont have enough ventilation.

What's with all the recommended caulking and making them air tight?????????????

In my opinion, this is detrimental to overall bat house success.

In my opinion, in every state in the United States, In June and July, bats in bat houses positioned in the sun are not trying to stay warm, they are trying to stay cool. During the summer, you can not put a piece of wood in the sun and keep the temepratures from exceeding 100 degrees, unless perhaps it is painted white.

Gary Springer

[Terry Lobdell]

Gary, I've had bats in bat houses for about 10 years..........I can assure you that they definitely do seek out heat, especially the mothers during latter parts of gestation, birth and raising of pups.......

Here in NWPA, ventilation does not seem as crucial to little browns as it does big browns..........

Big browns definitely like a lot of ventilation...........but they require heat as well.........

My big brown mothers when they have pups will still choose east facing boxes during very hot humid weather........I've seen them hanging out of the bottoms of boxes panting on those hot afternoons..........

I have around 70 boxes for them to choose from here on my property including some mounted facing north and in other cooler locations..........So I used to wonder why they still chose sunny locations during hot humid weather? The reason is that they still need that early morning sun............

The only time I get usage out of boxes mounted in cooler locations, is later in the summer and fall after pups are grown and all the bats in general don't need quite as much heat..........

Pups especially will use these cooler boxes...........pups appear to explore like crazy after they start flying..........

[Joe Spencer]

Hi all! Great topic. Could it be that they like both depending on factors such as area temperatures etc. Here is a BCI link with Tony Koch who built bat houses in his barn many years ago. His open ventilated design which has his bat houses mounted high in the barn was very effective and to the bats liking. Of course this is a nursery colony. They also mention Eric Korsten who has contributed greatly to this forum as well:
http://www.batcon.org/index.php/get-inv ... ry/45.html