Just A Pup

We have a large barn on our property that is home to what seems to be a healthy population of bats. Several people/groups rent space from us through the winter and into the spring to store their campers and trailers. We let the bats stay for free. Recently, one of our renters picked up their trailer, which had been stored for nearly a year with a tarp over it. When the tarp was removed, it was covered in guano, as expected. To our surprise, however, there was also an immature bat (known as a pup), most likely a Big Brown Bat (Eptesicus fuscus), on the tarp.


To give an idea of scale, in the photographs above and below, I am wearing a standard leather work glove. Big Brown Bats are common and widespread in North America, as they are known from southern Canada through the United States, with the exception of south Florida and southcentral Texas. Big Brown Bats often overwinter in buildings, though some will migrate and overwinter in caves. During the summer, they roost in buildings or hollow trees. An impressive fact about the species is that they can fly up to 40 mph.


Bats are very beneficial, as they feed on insects including wasps, ants, and beetles, some of which are serious crop pests. No need to worry about this little one. Pups often fall from the roosting location; those that can climb are often retrieved by their mothers. I took this bat back into the barn and climbed a short distance up a ladder before putting the bat near a vertical beam. It immediately began climbing up towards the rafters.

Special thanks to my coworker Jeremy Sheets for providing his opinion that this likely is a Big Brown Bat.

White-nose Syndrome, or Just White Fungus?

UPDATE 28 JANUARY 2010...

After personally observing the Big Brown Bat discussed in this post, Dr. John Whitaker has told me... "The material on the nose appeared to be from the hibernaculum and was a mixture of dirt and hair stuck to the nose area and peeled right off with a needle. It was not white nose." Good news.

White-nose syndrome has received a lot of press lately. This disorder, which is characterized by a white fungus forming on the muzzle of hibernating bats, is currently known to exist in the northeastern United States and west to Pennsylvania. In just the past two years, it has led to the death of over 100,000 hibernating bats (primarily Little Brown Bat, but also Indiana Bat, Eastern Pipistrelle, Northern Long-eared Bat, and Small-footed Bat). This is bad news if you don't like mosquitos; one bat can eat up to 75 percent of its own weight in flying insects during a single summer.

Photo from New York Department of Environmental Conservation, www.dec.ny.gov

On January 31, before our recent spring weather (which is about to revert back to winter, by the way), I found a dead Big Brown Bat (Eptesicus fuscus) just outside our back door. The bat was identified as a first year juvenile by Dr. John Whitaker based on my photos. While this little guy seemed pretty small when all folded up, when my coworker Rob Wolfe stretched it out to measure it, the wingspan measured a stunning 310mm! Other dimensions included: total length, 109mm; forearm, 43mm; tail, 41mm; hind foot, 10mm; and ear, 13mm, though this last measurement could have been conducted incorrectly.

Big Brown Bats can be found from southern Canada to northern South America, and into the West Indies. They can live up to 19 years, but many don't make it past their first winter because they don't store enough fat to last through hibernation. While all of our other species of bats migrate south and hibernate in warmer climates, the Big Brown Bat will spend the winter hibernating in cooler areas. They even will become active during this period of hibernation if they become too cold or if their hibernaculum is disturbed.

A variety of insects are eaten by Big Brown Bats during the spring-early fall, including dragonflies, moths, flying ants, flies, lacewing flies, and wasps. Most commonly, however, they feed on beetles.

It is possible that this bat died as a result of the cold temperature that it encountered when it left its hibernaculum. However, the white fungus on its muzzle makes me wonder if this bat could possibly have died as a result of white-nose syndrome, even though this disorder has not been observed as far west as Indiana (yet). The fungus on the bat I found looks a little different than the photos I've seen of bats that have white-nose syndrome. If anyone familiar with this disorder has thoughts on whether this is or is not white-nose syndrome, I would like to hear them.