Bat House Forum

[heynow]

Found my bats hanging under my bathouse one day I thought it was odd. They have moved out now I wonder why?

[Joe Spencer]

Sorry I overlooked this post.  Bats move for many reasons such as migratory, temperature changes and extremes, seasonal preferences, parasitic buildup.  We'll look forward to your feedback should they return to roost.

[IowaNate]

  It looks like they were overheated or perhaps there was a lack of other close available roosts. It's definately odd, but the moving out afterwards could be a seasonal migration as Joe suggested. The bats appear to be Mexican Freetails, which generally form large colonies, so I wouldn't be surprised if they come back soon since they have obviously been using your bat house in great numbers. Did you change anything prior to the bats leaving or did you notice a predator of any sort? 

  I had a colony of 150 little browns in a bat house and the number dropped to 20 in the course of one week during the summer. I noticed large raccoon droppings beneath the house and then one week later observed the raccoon standing on the railing of the deck just below the house with his paws in the crevices. He was spooked by a small rock striking him in the back (I hate to admit it, but I threw the rock). Within a month the colony was back up to 80 bats. Owls, hawks, and omnivorous mammals can definately make bats leave a roost. Parasites are generally always a problem with large colonies, but I have never seen all of the of bats leave from a bat house due to them, but I have seen up to half the bats leaving to another nearby roost to escape the bugs.

  Keep us posted on the houses, and any findings you might have!

                                                                                              Nate

[Terry Lobdell]

That is an excellent picture! I have had big browns hanging almost that low on hot humid days.

[kerbat]

heynow,

I had a similar experience of bats departing after hanging outside of box on hot afternoon here in S Florida, George Marks of Florida Bat Conservancy said 07 was the first year he had heard of apparent overheating in florida houses. My house was on the N side of our home and was also somewhat shaded by the roof overhang. House only got early morning sun and late afternoon sun and was single chamber painted grey. Had over 100 brazilian free tails and evening bats in the small single chamber box for a month before this incident Later got a colony of all free tails.

Later measured temps of 116 degrees in this house with it turned west while doing some temp investigation with colors etc. Ever measure the temp inside your house. You can buy a small sensor with 10 foot cable to a digital read out for $10 from Harbor Freight.