Bat House Forum

[Joe Spencer]

Below is some of the guano from the mega rocket bat house which was taken late in the season.  Note the difference in size of the guano.  The outer chamber directly above the largest droppings in photo was harboring a Big Brown Bat with the bat only inches above the bottom opening.  The smaller guano appeared to be from a little brown bat which was up and within the higher area of the interior chamber of the bat house.  It comes as no surprise knowing the different temperature preferences of both of these species.   Can't wait for next season for this house and I hope to get another rocket up nearby.


MUST HAVE LOST PHOTO will try again next year!

[Joe Spencer]

Just checked tonight and I have 3 little brown bats using this rocket and no Big Browns.  I'm quite excited about it since in my immediate area the Big Brown Bat dominates the spotlight.  I'd have to go about 3-4 miles to a wetlands in town to raise the odds of having little brown bats.  Certainly not great numbers but I'm glad to have them.

[Joe Spencer]

The little brown bats left some time ago and a big brown arrived late last month and you can see him as of today (Mid October 07) below.  In the outer chamber you can see a stuck piece of little brown guano where the little browns were previously.  I was quite excited to see two species in the same bat house.  The two separate species never chose to roost side by side that I could see.  The little browns were so far up that I couldn't get a photo of them.  Maybe next year on a hot night just before emergence I'll try again if they return.  I need to get another rocket bat house up.  I have never had little browns (only big browns bats) in my soffit bat houses mounted on my house just 20 ft. away.  If you look carefully you can see that the chamber the big brown is in is slightly larger than the 3/4" spacer.  Over the years I have seen big browns show a slight preference for chambers of 7/8" over 3/4".  Has anyone else noticed this as well?  BCI used to have similar data as well although it may be outdated. The outer chamber (seen below) where the little browns were is/was  3/4".

[Terry Lobdell]

Joe, My big browns seem to use 3/4 inch crevices as much as 7/8 inch. But it is hard for me to do very valid experiments here at my home due to shading from some trees which causes my bats to move around according to sun exposure throughout the season.

I had a real bat bug problem this summer and I'm certain they moved around for that reason as well.

You mentioned you've only had big browns in your soffet house. I have noticed my big browns heavily prefer houses mounted to buildings. My little browns strongly prefer houses mounted on poles. These preferences are greater with maternity colonies of both species. 

[Joe Spencer]

Thanks for the feedback Terry.  Very informative since that would explain why I have never seen a little brown in my soffit houses.  I of course attracted many bats to the bat houses on the shower building at my greenfield state park site in N.H. However, that is a different situation since there are no bat houses up there mounted on poles etc.  I'll bet when/if I mount a rocket or other bat house there on a post or pole I may get some converts.  Thanks again.

[Joe Spencer]

Had a couple little browns in this house for the last month and now I only have big browns utilizing it.