Bat House Forum

[IowaNate]

The bat houses mounted on my home have early occupants this year as well! My SE, NW dilapidated house (still haven't replaced it), and the new insulated house all have one big brown in them! Still no bats in the slanted baffle/hybrid house though. All three bats look very healthy and plump (I got within a foot of the bottom of each house).
The NW house that is in bad shape is still waterproof, but the roof is pulling away from the top of the house. Perhaps there is something beneficial with good airflow as Kent has suggested in the past, as this house always seems to have the most occupants.

The daytime high temps have been between 55 and 68 degrees for the last four days, with daytime temps only in the upper 40's by Wednesday.

[IowaNate]

Four bats total now at my home, with two in the worn NW house. There is no activity in the three houses I have mounted at the Nature Center yet, but it's still pretty early.

[IowaNate]

Still only four bats, and their choice of houses hasn't changed. The temperature has been dropping into the lower 30's during the night and rarely making it over 50 during the day. I hope that the other big browns made it through hibernation safely!

[mattkime4]

how long have the houses been up?

[IowaNate]

Three of them have been up for about 8 years, and the insulated and hybrid house have been up since last year. There has never been more than 9 bats at a given time.

[cloudman75]

I counted 74 little browns tonight on exit about 8:15 PM. We have had temps in the 60s and 70s with mild temps at night.
Tomorrow and Tuesday we have a cold front and expect temps in the 45 range daytime, and below freezing at night. Some may leave,but many had made it back from hibernation. I had about a hundred leave out in late Nov. I have never seen a big brown here in N.W. Georgia. They are supposed to dwell here but I have none. My third bat house I put up last year is still unused.

[IowaNate]

One more bat has chosen to roost in my newest insulated house, bringing the number up to 5 bats total. Still no luck with the slanted baffle hybrid house. I think the house is perfectly fine, but perhaps the Southwestern location isn't ideal for them. That hybrid house does tend to get the most amount of sun...so I think I need to keep experimenting on the North side of the house (ironically mostly shaded, but the bats seem to prefer it). Problem is, I only have a space 24" wide and 24" tall on each side of my upstairs windows. Something will be done this year on the North side, and I will commit to it to making it happen instead of not dedicating the time.

[IowaNate]

Brain-storming time again, and I hope all of you can help. I am not sure I should continue with any slanted baffle designs. They are slightly a pain in the bum to make, and I am not sure if the success is any greater than standard vertical partitions.
The 4 square feet of available space (once the bats leave for the season) needs to have something that can accomodate most of their apparent desires.

My observations thus far at my home
1-They prefer crevices at the 13/16" and 7/8" mark
2-A 3" landing pad seems to be adequate
3-They definately do not tolerate high heat, so vents in the lower third of EVERY chamber should be
added
4-Insulation seems to be a success, but it is far to early to make a conclusion judgement
5-Throughout the season, they frequently change roosts and chambers...and it doesn't seem that
parasites are a problem

Given my observations, I could try a few slight modifications such as
1-Extending the landing pad to a full 6"
2-Drilling a 1/2" hole that is 1/3 from the bottom on each side of my bat houses in addition to the
3/8" vent in the front
3-Cutting a 1-1/2" hole in the middle of each partition to aid in switching chambers without exposing
them to the outside

Any other suggestions would be greatly appreciated, and I am still thinking a nursery colony is a definate possibilty if I get these bachelor's needs figured out. Just to re-cap, there is a stream that is 10 feet wide on average that is just short of being exactly 1/4 mile away, 2 acres of wooded area within 200 yards, and multiple vegetable and flower gardens within 100 yards. So there is no shortage of diversified habitat and food sources.

[Terry Lobdell]

Nate, I think slanted baffle boxes are more suited for big browns during hot weather, especially facing east. Big browns really love that morning sun! I have not had any use of my slanted baffle boxes yet this year either. I think it takes about 3 years to really evaluate a box. Here at my home, both my bat species change their roosting behavior every year depending on what boxes I have available.

As of April 4th, I had 10 big browns all roosting in a west facing insulated house. I made a post of it earlier. They always stay in this house during cool spring weather so they can remain in torpor. When it is cool they don't want to be roused if there are no insects flying. Come warmer weather they will move into east facing houses.

My big browns seem to use 3/4" crevices as much as any other, but most everything I have read says they prefer 7/8".

I think a 3" landing pad is sufficient.

Ventilation is crucial. I am now making all my boxes with a back access/ventilation gap. Using one inch or 3/4 inch boards this is very easy to do just by leaving about a 5/8" gap between the boards. I do the same thing inside with the baffles to allow for internal movement between the crevices. When this type of box is mounted on a building with spacers, my big browns are always roosting in back on very hot days. I have this design mounted above my deck and I can stand underneath and watch them go back and forth throughout the day.
I built a bunch of new boxes this winter many of which only have venting with the gap in back. This also makes for easier construction.
Below is the link to pictures of the chimney mounted box of this design
viewtopic.php?f=5&t=555

My big brown maternity used 12 different boxes last year! Of the 12, the chimney box and the popcorn tin box were the favorites. Much of the summer, my big brown mothers were split into 2 groups. When pups first flew on July 15th, half were in the popcorn tin box and half were in the chimney box.

Big browns just seem to move around to different roosts more than little browns do. The number of big browns you have there sounds like you have some females. I'm guessing it will be just a matter of time before you get some mothers with pups.

I think to get big brown mothers with pups you've got to have some east and or southeast facing boxes. I rarely ever have my big brown maternity roosting in a south facing box.........probably too hot and not enough morning sun.

[IowaNate]

The insulated house now has three big browns in it. The total number of bats hasn't changed from 5, but they seem to prefer this new house at the current time. Due the the construction and placement (mostly shaded) it is probably the house that is least affected by outdoor temps, thermal radiation, and wind.
We are insulating the exterior walls of our home this Spring, so there might be some thermal changes taking place in the bat houses. It will be very interesting to see if insulating our home affects the bats in any way.
I am still thinking of ideas for 4 new bat houses mounted on each side of my upstairs windows. I have one idea that involves something a tad bit extreme (sharing the attic crawl-space air with one of the bat houses through a screened hole in the wall). This needs alot more thought, but would be VERY easy to do to perhaps extend the length of the bats' occupancy each year.

[IowaNate]

I removed the Northeasterly house and relocated the slanted baffle hybrid in it's place. The big browns have dispanded except for two bats, one in the insulated house and the other in the Southeasterly house. I figured this would give me some time to experiment a little and hopefully see if the bats actually start using the hybrid house.

[IowaNate]

Moving the hybrid house was a success! I had one big brown occupy it for about a week, although it was using the standard vertical partitions when I observed it for a few days. But currently I am down to one bat residing in the Southeasterly 3 chamber house.

[Mulator]

Something is going on here....you guys all have bats already? I haven't see a single one this year yet...wonder what is up with that? I live in Haymarket, VA. You think maybe all the rain has affected their area?

[Terry Lobdell]

How long have you had your box up? Did you have bats roosting in it last year?

[IowaNate]

I have had no daytime occupancy for the last two weeks or so, but there is something interesting I am noticing. Almost all of the bat houses have newer guano stuck below them on my house. I say "newer" since I find new droppings every few mornings.
I am not sure if they are using the houses as nightly digestion stops, or investigating the houses and pooping while in flight.
It has been very hot here with daytime temps in the upper 90's for the last ten days as well.