Bat House Forum

[Terry Lobdell]

Tonight after an exit count of my big brown maternity colony I shined a light up  and saw pups in the 2 houses the adults exited out of. One house had 4 bats exit and exactly 4 pups inside. The other house had 12 bats exit and about that many pups.

I have always read that big browns usually have 2 pups. Last year and this year my numbers seem to indicate that mine are only having one pup. Anyone have any observations on this subject?

Also, between June 1st and 6th, my big brown maternity colony disappeared altogether. I'm wondering if they went somewhere else to have their pups. I've never noticed such a thing in past years. Has anyone else noticed a maternity colony leaving briefly to give birth then coming back?

[Joe Spencer]

Yes they usually do have two pups and from what I understand the gender is usually different too with both a male and female pup being born.  I have only seen the latter on a few sites in recent years so I'm unsure of its validity but it is nonetheless quite interesting.  When big brown pups are left behind it is because they're finally too heavy to ride on and with mother.  At this point within days the pups will soon be foraging on their own.  Weaning from mother is paramount so that she will be able to store her own fat reserves for hibernation.  Terry, it is unusual that you're observing one pup being born more frequently than two.  Great observance on the colony leaving.  I have only witnessed it once and I'm clueless unless it has something to do with the parasite factor or a temperature issue which needs to be satisfied/warm but not too hot for big brown maternity colonies to enable the young to grow quickly.  Maybe someone else can lend some insight and feedback.

[Terry Lobdell]

Joe, I've had big browns leave briefly later in the summer when it got really hot but this was the first time they've left in June. Or maybe I just did not notice it before.

This colony has roosted in 6 different houses so far this year.

My big browns have always rotated around different houses more so than my little browns.

The pups I observed tonight were very small, no fur and eyes closed. Their heads were about a half an inch in diameter and their bodies were about an inch and a half long. They were roosting clumped tight together.

They were roosting in the single crevice-back vent houses I posted pictures of previously.

[LarryH]

Terry, all of my Big Browns left early in June this year because we got a very early hot spell in which the temps were in the mid-90's.  This is the first time since I've had bat houses that the Big Browns left this early.  Last year, they were in the houses throughout June and reaised their pups there.  But, the only pups I have this year are Little Browns, and all of the Big Browns seem have gone where they could find cooler houses to raise their young.

I do have a few different bats this year that I am not sure what they are.  I think they may be Evening Bats, since the pictures of Evening Bats I found on the Batcon page look a lot like the ones I have.  I had not seen any like these before, and I'm glad to have a variety.  If they are Evening Bats, maybe they will get rid of some of the Japanese Beetles that we normally start getting about this time of year -- I haven't seen any of the beetles yet, so maybe they're already eating them....

Larry

 

[Terry Lobdell]

Larry, I wondered about that same possiblitiy when my big browns left because we had the same heat wave. But I have houses that would have been cool enough.......maybe they just did not want to roost in houses they weren't used to.

That is interesting about the evening bats. From what I've read, I am too far north to attract evening bats.