I have an old barn that holds a maternal group of Big Brown Bats. In early June the bats start having their babies (pups). Every year I’ve lived there I’ve come across some pups (5 to 10 per year on average) that have fallen off their mothers while their mothers were at roost in the barn. When I find a pup I put on some leather gloves and grab a screwdriver and a paper cup. I gently guide the bat into the paper cup and use a ladder to climb the pups up some 15 feet to a cross beam in the barn. This brings them closer to the roost where the mother has a better chance of hearing their ultrasonic distress calls, locating them, and retrieving them.
This year, for some reason, has not been a normal year. This year I’ve been keeping track and I have found 44 pups on the barn floor. I would say 1 out of every 5 were dead meaning I’ve found about 35 live pups. They seem to survive the ~35 foot fall quite well. I assume they know enough to spread their wings while falling in order to slow their descent. The ones I find that have not survived either were very small or they landed on their back. They are unable to turn over if they are on their back. Of the ~35 pups that have survived the fall that have been placed up 15 feet up on the cross beam, only three have died. These three were just too small to vocalize so the mother could not hear and locate them. I’m assuming the other 30 were located and retrieved by the mother. I’ve got to believe that I’ve handled some of the pups multiple times. This is because the most bats I’ve counted in the barn is 30. The bats have one pup a year and, 12% of the time, have two. That means that 30 females would produce ~33 pups.
Anyway, sorry about the mini blog. I’ve read that overcrowding and overheating can cause pups to be jostled or weakened to the point of falling, but neither of these scenarios seem pertinent (large barn and not an overly hot June).
So, does anybody out there have a maternal colony that roosts in an outbuilding/barn? Have you found more pups this year than normal? Probably a long shot, but I’m curious and thought I’d throw the questions out there.
