Who is that flying in the night sky?
Glenn Nelson, Education Coordinator
Fall means less daylight and time to bring in the harvest. It's also the season for Halloween. Watch the evening sky and you'll notice a furred animal with "hand-wings" in frenzied, erratic flight. Its appearance to some people can be somewhat scary and frightful. Yet once you get to know this night creature, you'll realize it's quiet helpful to you and important for insect control. Yes, you can see the mammal that masters the sky and feeds on the fly in all the Chester County Parks.
The Creature Future seasonal spotlight, or even better, "moonlight", falls upon bats, the only mammals that are truly able to fly. Bats fly by actually flapping their wings to propel them in flight. Their wings are thin membranes of skin stretched from fore to hind legs and hind legs to tail. Their long, slender finger bones act as wing struts, stretching the skin taut for flying; closed, they fold the wings alongside the body when they roost. In fact, bats belong to their own unique order called Chiroptera, meaning hand wings.
BAT BENEFITS: Bats make good neighbors. Because they do fly, these nocturnal creatures play an important role in controlling many insect pests. A single bat can consume as many as 500 insects in just one hour or nearly 3000 every night. Think about what a colony of 100 little brown bats, the most abundant species in the northeast, may eat almost a quarter of a million mosquitoes and other small insects each night.
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{Little Brown Bat} |
| Little Brown Bat |
THE LITTLE BROWN BAT (Myotis lucifugus): The scientific name refers to flee from light. This animal is Pennsylvania's most common bat that belongs to the Vespertilionidae, the evening or common bat family. This family is made up of insect eaters, taking prey on the wing.
FEEDING BEHAVIOR: A unique feature of bats is their use of "echolocation". This simply means using reflected sound waves to locate their prey. During flight, a bat utters a series of high-pitched squeaks, which echo off nearby objects and bounce back to the bat's big ears. Split-second reflexes help the bat change flight direction to dodge obstructions or intercept prey. A bat will use its mouth to scoop a small insect out of the air. For larger insects, bats disable them with a quick bite then cradles the bug in a basket formed by the wings and tail. Bats chew up their food with sharp teeth, turning insects into easily digested pieces.
NATURAL HISTORY: Little Brown Bats live in any area close to trees and water. During the day, bats roost by hanging upside down by their feet. Bats seek out dark, secluded spots such as caves, hollow trees, and rock crevices. They may also congregate in vacant buildings, barns, and attics.
Despite their nightlife, bats are slow to reproduce with one single young born each year. Because of the low reproductive rate, bats tend to live up to 30 years. Most bats mate in late summer or early fall, however, the sperm is stored until spring when fertilization occurs. The young are born in summer; blind, naked, and helpless. Babies nurse on mother's milk like other mammals.
Bats are true hibernators since most insects disappear in the winter. During the winter, they eat nothing, surviving by slowly burning fat gained during the summer and fall. This also explains the delayed fertilization until spring since the mother would have little hope of successful pregnancy during hibernation. A hibernating bat's body temperature drops close to the air temperature. Many bats die when people or other disturbances rouse them in the winter. They do NOT have enough energy reserves to have their hibernation disrupted!
| {Little Brown Bat eating a moth.} |
| A Litle Brown Bat attempting to each a moth. |
That's why you see so many bats in the October sky feeding frantically to build up their body fat before the insects disappear for the season, not because of any association with bat activity to Halloween. Before bat behavior studies, people noticed that bats disappeared during the day and became active only after sunset. This behavior caused early human cultures to think that bats may be part of the underworld and may have led to bats becoming a symbol related to Halloween.
CREATURE WATCH: Bats may be viewed in all of Chester County parks especially at twilight over fields, night-lights, and water surfaces, prime insect feeding areas during the summer and fall. During the winter and early spring, please do not enter bat hibernation areas.
WHAT YOU CAN DO: You can reduce mosquitoes in your backyard by hanging bat boxes for a neighborhood roosting site. Bat box designs are available from the Pennsylvania Game Commission (PGC) at thier website:
www.pgc.state.pa.us under wildlife then bat link or the regional office call 610-926-3136.
SOURCES:
• Pennsylvania Game Commission, Wildlife Notes on Bats
• Penn State College of Agricultural Sciences, Cooperative Extension: A Homeowner's Guide to Northeastern Bats found on the PGC website.
