BASICS OF BATS
Dr. Leonard Perry, Horticulture Professor Emeritus
University of Vermont
Bats are important to ecological systems worldwide, their role varying with region. In our temperate region they consume huge amounts of insects—up to their body weight in one night. A favorite food in this country is the corn earworm moth which damages many commercial crops, from cotton to corn, artichokes to tomatoes and watermelons. One estimate is that bats save more than $3.7 billion in crop damage and reduced pesticide usage. This latter, in turn, also helps the environment.
From the tropical rainforests to deserts, bats pollinate a wide
variety of crops and plants from bananas to peaches, carob to
agave. They also help to disperse seeds, particularly in areas
cleared of their rainforests for lumber. This has earned them the
nickname “farmers of the tropics.”
That’s the good news. The not-so-good is that bat numbers are
declining globally. The International Union for the Conservation
of Nature lists 26 species as in imminent risk of extinction, 51
other species endangered, and 954 bat species vulnerable. Most
the reasons relate to human activity, a large reason being loss of
forest habitat, particularly tropical rainforests.
In some Asian countries, bats are hunted for food or folk
medicine. In Latin America and other areas, they’re killed due to
misplaced fears and inaccurate myths (such as them being
vampires). As wind energy and turbines have increased, so have
their impact on bats. But new technology has been developed and
proven effective in keeping them away from turbines. Pesticides
have killed off many of the insects they feed upon, and
contaminated insects eaten by bats have killed many. Most
recently in North America, over 5.7 million bats have been killed
by the white nose syndrome disease.
Here are ten amazing bat facts to give you a better appreciation
of this mammal.
--They have super hearing, using “echolocation” or reflected sound waves, similar to dolphins, to locate objects. Their “sonar” system makes high frequency sounds that bounce off objects, returning to them as an echo.
--Many have good night vision, so the phrase “blind as a bat” isn’t true
--Some bats have an internal “compass” that uses the earth’s magnetic field to navigate
--Some bats have “heat vision”, using specialized nose sensors to locate prey
--Some desert bats are resistant to the most venomous scorpion stings
--Bats are the only mammals capable of true and sustained flying, due to their webbed wings. Some bats can fly up to 60 miles per hour
--They are the second largest group of mammals, only surpassed in species by rodents
--Most bats only give birth to one “pup” at a time, which makes them vulnerable to losses and is one reason for declining numbers. Yet this makes sense since a pup can weigh up to one-third the mother’s weight. In the human context, imagine giving birth to a 40 pound baby.
--Bats are some of the most diverse animals on earth, their faces alone varying tremendously.
--Many bats sing as much as songbirds, with tunes similar and often more complex including rhythm, elaborate structures, and even rules for how they combine phrases.
Bat species can be placed into two groups—colonial bats that live
in colonies, often around buildings, and solitary bats that
typically live singly in tree foliage or under bark. Two species
are most commonly found in much of our country—the little brown
(colonial) and big brown bats (generally solitary males and
colonial females). Virtually all species in North America eat
insects in huge amounts and all types, including mosquitoes. The
little brown bat, on a good night, can consume one-third of its
body weight in only a half hour.
Although bats mate in fall and spring, young are only borne from
May through July. The pups are ready to fly away within three
weeks. Mothers don’t live in nests, but all manner of protected
places such as in buildings, behind chimneys, under bridges, in
caves or tree hollows, and similar.
About the time of first frost, bats start preparing for winter.
Some species migrate short distances, others migrate 1,000 miles.
Most species in North America hibernate, perhaps from October
until May, flying about some during warm winter spells.
Sometimes bats can get inside buildings. You’ll also learn how
to deal with bat problems at the Internet Center for Wildlife
Damage Management (icwdm.org). It’s important to keep in mind
that healthy bats don’t normally attack humans, even if chased.
There are some great tips on how to deal with such a situation, as
well as what to do if you find an injured bat, from the Vermont
Bat Center (www.vermontbatcenter.org). This site also has useful
information on bat houses and links to sources and websites with
plans to build your own.
Bat houses are flattened wood boxes, open on the bottom, with
single or multiple roosting chambers. Height (12 feet or more off
the ground), location (on buildings is best, but poles can be
used), orientation (generally toward the east, away from
prevailing winds), and color (black to absorb heat in cold
climates) are all important considerations.
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