Post-Volant Emergence Count of Bat Colony at the Green Barn

On July 25^th a second count of the bat colony in the Green Barn yielded a total of 167 Big Brown bats. The previous bat survey took place May 30^th when James Fischer and I counted 127 bats. The May count represents the number of bats before the pups begin to fly (pre-volant) and the July count represents the number of bats after the pups begin flying (post-volant). Therefore, the comparison of this data gives us reliable information about reproduction rate, as well as population growth. It is always a positive sign to see the number of bats increase, although we would have liked to have seen an even higher count, such as in 2010, when 286 bats were counted at the Green Barn. Since White Nose Syndrome is still spreading and devastating bat colonies, the data that is collected is critical in helping researchers measure the fallout of this disease and further explore other possible factors affecting bat population. We have observed that weather conditions greatly affect whether or not bats leave their roost at sunset. On July 18^th we attempted to do a post-volant count after a very hot and humid day with late afternoon thunderstorms. We were able to count only 105 bats emerging from the Green Barn and afterwards concluded that the data was inaccurate due to weather. In my opinion, bats will always be a unique and mystifying species. Their imperative role in our ecosystem should always be appreciated and we need to continue to protect these creatures as much as possible.


Two of Gerri Griswold's Big Brown bats.