for the Gloucester County Nature Club
One of my simple pleasures of summer evenings in past years was watching bats as they circled through the evening sky over my house, catching insects by the hundreds.
It was worth risking a few mosquito bites to see. There were always half a dozen of them. Usually they were just little brown bats. Sometimes they were joined by a larger species, which I guess was a big brown bat. These are not very precise names, but nobody has yet written a book to identify bats in flight in half-darkness.
But this year, there is only a single bat, or in some nights no bats. What happened?
Chances are that my bats are dead, along with many thousands of others. They were probably killed by white nose disease, which has been killing bats in the eastern United States for the last seven years, and has been spreading westward.
It has killed 90 percent or more of the bats in some areas.
At one wintering site in New Jersey, in old abandoned iron mines of Morris County, numbers dropped from as high as 30,000 in past years to just 600 last winter. And it’s not known if the few surviving bats are resistant or just lucky.
This fungus disease first appeared in North America in 2006, at a cave in upstate New York. Its origins are unclear. It might have come from Europe, since European bat species are resistant to it.
It primarily affects bats as they hibernate, and causes them to wake from hibernation and use up their fat reserves. The animals then starve to death. The fungus shows up as patches of white around the nose and mouth of the affected bats. Thus the “white nose disease” name.
Nine species of bats are known from New Jersey. The hoary bat, silver haired bat, and red bat are non-colonial seasonal residents that are here during the summer but winter south of us.
The remaining six New Jersey bat species are year-round residents. Three are “myotis” or “mouse-eared” bats. These are the little brown myotis, the small-footed myotis, and the Federally-endangered Indiana myotis.
All are small, with a wingspread of 10 inches or less, and brown.
Non-myotis bats include the eastern pipistrelle, the northern long-eared bat, and the big brown bat.
The little brown myotis is (or was) by far New Jersey’s most common bat species, and it shares its year-round life cycle with the other myotis bats. They hibernate in winter in caves or abandoned mines, and they will travel for long distances to reach these sites. Young are born in the spring, one per female.
In the summer the sexes separate, and the bats roost in buildings, caves, or hollow trees. Male roosting colonies are small, but female “maternity” colonies could have hundred of bats in them.
For information about the Gloucester County Nature Club, see gcnatureclub.org/.