Vermont. July 1, 2011. Any evening as we come to dusk and there are insects hatching out of the water, flying in the air over the water and landing ever so briefly on the water, delicately laying eggs, you are likely to find at least two other species sharing the same river reach, flyfishers and bats. The human flyfisher is there to fool trout with imitations of the insects. The bats are there to earn their living.

Bats are consummate flyers and their bodies are superbly designed to catch insects and using echolocation they seldom miss their flying targets. During a typical night of foraging a bat may eat as much as one-half its body weight in insects. Bats are the only true flying mammal and are remarkably long-lived for their small size, some living for over 20 years.

Bats have been around for over 50 million years and are in the taxonomic order Chiroptera. The word is a combination of two Greek words that mean “hand” and “wing.” Bats do not fly by flapping their arms but by flapping the fingers of their hand at the end of what would be their arm. The sub order of our common bats is Microchiroptera which means that they are small in size and hunt by echolocation using bursts of sound that echo locates their targets.

There are about 1,240 bat species worldwide, a number that amazingly represents about twenty percent of all classified mammal species. Apart from the Arctic, the Antarctic and a few isolated ocean islands bats exist all over the world.

Most bats drink water by skimming the surface of a body of water, and lowering their jaws to get just one drop of water, consume it and go back for another drop until their thirst is slaked. Other bats gently skim the surface of the water then land nearby to lick water from their chest fur.

There are nine bat species that live in our watershed. The Indiana bat and small-footed bat are rare; northern long-eared bat, eastern pipistrelle, silver-haired bat, red bat, and hoary bat are uncommon; and little and big brown bats are common. Of the nine, six hibernate over winter in the region while three – silver-haired, red, and hoary bats – migrate south.

Bats provide U.S. agriculture at least $3 billion a year in non toxic pest-control services, according to an analysis published in Policy Forum of Science magazine. This does not include the value of mosquitoes eaten around your home, making your outside experiences at night and during the day that much more pleasant.

The threat that puts our bug eating friends at risk as a species is White Nose Syndrome (WNS), a fungus spreading through hibernating bats. It is thought to kill upwards of 75% of the bats exposed to the fungus. The mechanism by which WNS kills remains a mystery. WNS now infects bats in 18 states and four Canadian provinces. WNS was found in VT and NH in 2009 and 2010 but is not confirmed yet this year. WNS has been reported in 12 European countries but unlike our epidemic the European infection has not yet been associated with mortality.

In most species, females give birth to only one offspring per year and many of the young do not make it through their first year. A low birth rate coupled with so many bats dying of WNS means at best it will take decades for the bat populations to recover, if they ever do recover. Extinction is another possible result of this epidemic.

So if you end up with a bat inside your house do not kill it. We need every one of them to stay alive. The most straightforward way to remove a bat is to open a window to the outside and close everything else. The bat wants out more than you want it out. No individual bat is any more likely to have rabies than any other mammal, so caution is in order but not hysteria. If the open window plan does not work both the Vermont and New Hampshire Non-Game Natural Heritage Programs have on their web sites clear non-lethal instructions on how to remove a bat safely to the outside.

An approach that could help address bats roosting inside your house and the WNS epidemic both is to build or buy a simple bat house. Scientists feel that offering small warm summer roosting locations for bats could boost the odds that bats will reproduce successfully. If you bat proof your house then having your resident bats relocate to the bat house will keep your insect eater working to improve your outside experience. A good place to start looking for bat houses is through Bat Conservation International or the state Natural Heritage Programs.

Watching bats at night is one more rewarding experience we can enjoy when we go on the river.

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David Deen is River Steward for the Connecticut River Watershed Council. CRWC has been a protector of the Connecticut River for more than half a century.