Nature Nearby: Night of the hunter

October 10, 2011

FRED SEITZ

BY FRED SEITZ — As dusk sets in, an aerial ballet begins in the sky over Magruder Park and the Northwest Branch.  Birds are retreating to their evening roosts and a nocturnal cast of flyers take to the air.  A few swallows skim along the grass in the park. Evening walkers along the bike path become acutely aware of the annoying bites on their arms from dozens of mosquitoes that seek them out.  But if conditions are right, the walkers may also notice larger flyers circling lampposts or making erratic patterns among the trees and near the water.  These are some of the benevolent bats that inhabit the trees and some attics or other buildings in the area.

Bats are the world’s only flying mammals. (Flying squirrels are gliders, and do not actually fly).  Much misunderstood and maligned, bats are not only remarkable because of their flying and hunting abilities, but also because they are a very important method of natural pest control for both mosquitoes and serious agricultural pests like moths. (Paul Cryan, a USGS Biological Survey scientist recently estimated that bats save U.S. agriculture $53 billion through their pest control.) Bats are not rodents, as often thought; in fact, their bone structure is more similar to humans.

There are 10 species of bats that live in Maryland; of these, at least three types live in the Hyattsville area.  Early risers – in the evening,  that is – include the beautiful red bat, which often circles lampposts in the early evening, and the little brown bat, who will flitter through trees and along hedges. The third is the big brown bat, which is a separate species from the little brown, despite the similarity in the common name.  Other Maryland species may also live in the area, but they are somewhat less common (or at least less noticeable, as their night shift begins later than these three).

The red bat lives in trees and overwinters in the area, due to a natural antifreeze in its blood.  If you enjoy corn on the cob, this is your bat, as it preys on corn borer moths and their caterpillars, who often ruin the appearance and edibility of corn.  The little brown bat also eats moths, but is a big fan of mosquitoes as well.  Little browns will often get into attics or chimneys and are the bat most likely to occupy bat houses.  They usually migrate in early fall and will hibernate in cooler areas (caves, rock overhangs or abandoned houses in cooler areas).  If little browns do occupy your attic or garage in summer, simply wait for them to emerge in the evening and then place screen over their exit hole.  This is a much better (and cheaper) way of addressing a “bat problem” than hiring an exterminator.  If one gets in the house, place a plastic bowl over it and slide cardboard underneath the bowl and release the bat outside: a simple way of evicting your batty guest.

Much of bats’ maligned reputation comes from film and media portrayals of bats as rabid vampires. All bats in Maryland eat insects, and they do a service to folks by eating the mosquito vampires that are far more common and carry a myriad of diseases dangerous to humans.  Bats, like all mammals, may carry rabies, but humans are far more likely to be bitten by raccoons or feral cats, which are significant rabies vectors.  Indeed, in the past 50 years only 40 people in the U.S. have died from bat strains of rabies; the last human death from a bat strain of rabies in Maryland was in 1976.  Like most animals with rabies, bats will not behave normally if they are infected. Not handling a bat on the ground is your best protection, but being wary of raccoons or feral cats is also prudent.

Unfortunately, our benevolent batty friends are suffering loss of habitat and from a fungus-borne disease (white nose syndrome) that has seriously diminished their numbers. Indeed, nightly walks in Hyattsville seem to reveal fewer bats in the sky than in previous years; though the local explanation for this is uncertain, the Maryland Department of Natural Resources has suggested that white nose syndrome may be the cause.

More about these fascinating animals and their remarkable echolocation and lifestyles can be learned online from the Maryland Department of Natural Resources oBat Conservation International (BCI). And since this just happens to be BCI’s International Year of the Bat, what better time to get to know these unique Hyattsville residents?

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