Bat House Forum

[Terry Lobdell]

Got a call from my cousin today.........he said he counted at least 55 little browns exit this house last night. We mounted it a couple years ago and it had usage by bachelors only........this house is a couple hundred yards from the house I posted previously on the light pole, so it could be the same colony.........but even if it is, numbers wise it is a big increase from my last year's count of 25 before pups were born!

[Terry Lobdell]

This house is only a 2 crevice box with maybe 3 square feet of roosting space! The front crevice is saw kerfed rough sawn wood and the back crevice is pet mesh. It is vented in the front and the back crevice is vented on the side. It is located right next to a very high quality trout stream (muddy creek). The habitat is excellent, mixed forest, farmland and pasture, a few orchards too........

[IowaNate]

 Excellent news Terry! As you said, even if it is the same colony from the former house, the colony more than doubled this year! And the description and photo of the location look excellent.

[Terry Lobdell]

Well..........My cousin, his wife and a friend did another exit count tonight.............I went over and did an exit count at his Mother's house on the light pole bat house.......only 6...........when I came back over to his house he had a big suprise for me...........74 little brown bats exited from this house!! It only has about 3 square feet of roosting space maximum............I was real happy!!

[Terry Lobdell]

We mounted another bat house a few feet away from this one..........the very next day it had guano under it! It was previously used at another location this year by bachelors so I think the scent inside may be why it was used so quickly. I will post a picture soon!

[Joe Spencer]

Well..........My cousin, his wife and a friend did another exit count tonight.............I went over and did an exit count at his Mother's house on the light pole bat house.......only 6...........when I came back over to his house he had a big suprise for me...........74 little brown bats exited from this house!! It only has about 3 square feet of roosting space maximum............I was real happy!!

And rightfully so Terry!  Nice work by all of you.  This is indeed some prime bat habitat the "right next to a very high quality trout stream (muddy creek)".  Maybe this would be an ideal spot for mist netting or a harp trap. Congrats...

[Terry Lobdell]

The 2nd bat house at this site has quickly been used. As I said earlier, it had guano underneath after the first night. We shined a light up about a week later and it had at least a dozen bats in it. I'm glad I got it up because my cousin has counted 3 fallen pups from the first house.

One thing I've learned from this..........the first bat house pictured in this post has about 3 square feet of roosting space.........And the highest exit count was 74........so doing the math,  if a box has 25 mothers per square foot there will be pups falling.

I wonder if Kent has any figures on this?

[Terry Lobdell]

Here is the 2nd bat house I mounted to give them more room. The house had guano underneath the first night and has been used previously at another location.  I think this method works well to attract bats quickly. Judging by guano, I'm guessing it had about 20 roosting a couple days ago. I stenciled a bat on the front so people driving by know what it is.

[Terry Lobdell]

The bat house has 3 crevices. The 2 front are 3/4" & the back is 7/8". The back baffle is plastic mesh and the 2 front ones are rough sawn wooden lathe. The exterior shell is 3/8" plywood. The roof is aluminum. To mount it, I screwed two larch cross pieces to the pole and 2 to the bat house. The edges on all 4 have a 45 degree angle which allows the top and bottom sets to interlock.

[Terry Lobdell]

Here you can see how the cross pieces interlock. The bottom cross piece also serves as a landing pad. It was a fast easy way to mount this house. My cousin and some friends did an exit count tonight. 41 exited the original box on the left and 36 came out of the new box with the bat stencil on the right. Hopefully this will eliminate overcrowding. The box on the left unfortunately has had a total of 5 fallen pups so far.

[IowaNate]

 Terry, given my observations (and personal math) a two chamber house with three square feet of roosting surface should be able to hold 120 adult little browns. So I think your figures seem very correct for 25 mothers per square foot. I have always based my figures on an adult little brown being approximately 1.125" wide and 2.5" long then taking the total number of bats based on that size times .75 for a more conservative number for the whole house capacity. And with pups it decreases the amount of adult bats even more. 25 nursing little brown bats with young per square foot might become my standard for estimating nursery house maximum capacity now.

  Thanks for the insight Terry!

                                                        Nate

 

[Terry Lobdell]

Your welcome Nate! Before pups were born, we shined a light up in the first house and both crevices were about 1/3 to 1/2 full. This was the night we got an exit count of 74 adults.

There have been at least 5 fallen pups from this first house. None from the 2nd house which is much larger, (3 crevices, probably about 2 & 1/2 times bigger than the first house.)

On July 4th, my cousin and a friend got counts of 41 in the first house and 36 in the 2nd house on the right. So I am pleased so many bats are using the new house! It's only been up about 3 weeks.

What I am wondering now is...........if an occupancy of 25 mothers per square foot causes pups to fall, what would be the maximum safe number of mothers so that pups don't fall? Maybe 15 mothers per square foot to be on the safe side?

 

[Terry Lobdell]

We did an exit count here on May 25th, 2009. The box on the right with the bat stencil had around 50+ little browns. The original box on the left I have since replaced with a bigger 4 crevice box to alleviate crowding. It had around 20 bats. We got a total count of 72 little browns so our numbers are about the same as last year.

The other 3 boxes across the creek only had a total of 5 bats. I think the difference in numbers are due to amount of sun exposure.

[Joe Spencer]

Well that is good Terry. I wonder if WNS affected the chance of having it increase over last year. Does anyone know of any photos of a WNS bat roosting in a bat house? I would assume it is rare or improbable since the disease propagates in hibernation and they usually die before the spring/summer roosting time but I'm curious about it. Haven't googled it yet.

[Erik]

Hi Joe, reacting on your question on possible sightings of WNS on bats in bat houses.
The very visible white fungus on WNS-affected bats is only visible on bats that are in hibernation or on dead bats. As soon a the fungus is being touched (for example when a bat is grooming itself) it disintegrates and becomes invisible. The other signs of WNS (small white fungus spots and deteriorated skin) are not very visible from a distance, for example when looking into a bat house from the ground. The very visible WNS-fungus also grows only in low temperatures and high humidity. So I guess in spring or summer it would hardly be visible in bat houses.
Bu whoever finds dead bats in or underneath the bat house, put in a tight sealed box or bag in your freezer and contact the WNS-officials*. Make a note of the date and place you found the bats and any other information that you think is relevant for research. Especially when you live in or near a WNS-effected area. They might need it for research.

*Joe /Terry: can you make a post on the forum on what to do when you find a dead bat in / underneath a bat house. Who to contact? Those findings could be very important for WNS-research. It is still possible that the Fungus is not the killer but a symptom coming from something else. The cause might still be in something that happens in summer period, making the bats vulnerable to WNS in hibernation.

greetings,

Erik