Bats: Chiroptera
Appearance:
Bats belong to the order Chiroptera, which means "handwing".
They are the only mammal that can truly fly. Florida has 13
resident bat species. Contrary to popular belief, bats are not
blind. Their vision is adapted for low light levels. However, bats
can maneuver in complete darkness using echolocation. Echolocation
is the use of sound waves to detect objects. Bats emit high pitched
sounds and listen for them to echo back. The length of time it
takes the echo to return tells the bat how far away it is from an
object. This allows the bat to fly in the dark and hunt for food.
Bats' feet are uniquely adapted for grasping structures so that
they can rest while hanging upside down. Bats undergo a state of
torpor in the daytime; their heart rate and body temperature
decrease so that they can conserve energy. Because of this, bats
are reluctant to fly in the daytime even when disturbed. If they
are forced to fly, they must first raise their body temperature and
heart rate.
For their size, bats have the longest lifespan of any mammal.
Some can live for more than thirty years.
Habitat:
Bats live in many different habitats across Florida. They can be
found from sandhills to the hardwood forests along the banks of
rivers, and probably even in your neighborhood! For bats, one of
the most important parts of their habitat is an area to roost. Some
bats, like the Brazilian free-tailed bat, the evening bat, and the
big brown bat are colonial, meaning they gather together in a
colony to roost during the day. Other species, like the Seminole
bat and the tricolored bat, are solitary, meaning that they roost
by themselves. In Florida, natural roosting sites can be cracks,
crevices, and hollows of trees, caves, dead fronds of palm trees,
Spanish moss, and tree foliage. Bats also use manmade structures
including buildings, bridges, culverts, tile roofs, and bat
houses.
Behavior:
Florida's native bats are insectivorous, meaning they eat
insects including beetles, mosquitoes, moths, and other agriculture
and garden pests. In fact, bats are the most important controller
of night flying insects because a single bat can eat hundreds of
insects a night!
In Florida, bats mostly mate in the fall and winter. The female
does not usually ovulate until the spring when the insect
population increases, but she can retain sperm for months before
ovulation occurs. Most female bats only have one pup per year. For
their size, bats are the slowest reproducing mammals. Pregnant
females of some species will gather together in nursery colonies.
Bats do not build nests. They normally give birth from mid-April
through July, and their young begin to fly within 3 to 6 weeks.
Juveniles are then weaned from their mothers and by mid-August the
young are able to forage and fly on their own. Bats will not reach
reproductive maturity until they are about one year old. This is
considerably longer than most small mammals.
Bats and People
Bat populations are declining in many areas. The loss of
roosting sites (such as trees and caves) can cause bats to roost in
areas where they are more likely to become a nuisance for people.
The use of pesticides to control insects can take away the food
that bats eat, and sometimes poison the bats themselves. These
unique mammals have been sensationalized in the news and horror
movies, creating a great deal of anxiety among Americans. Fear of
rabid bats has caused mass destruction of bat populations for
decades even though they seldom pose public health problems.
Ironically, this fear has caused more people to come in contact
with bats while attempting to eradicate them! Rabies, a virus
usually transmitted from a bite, affects a very small portion of
the bat population in Florida. Histoplasmosis is a respiratory
illness caused by a fungus. This fungus is found in soil that is
enriched with bat or bird feces. This fungus is sometimes found on
chicken farms or in caves. According to the Florida Bat
Conservancy, "this illness has been associated with bats in Florida
in only a few cases, all of which involved visits to bat caves".
Attics and roofs are normally dry areas that do not provide the
proper conditions for this fungus to survive. For more information
about bats and rabies or histoplasmosis, including what to do if a
person makes contact with a bat, contact your county health
department, the Florida
Department of Health, or the Centers for Disease Control and
Prevention (CDC).
Bats, like many other wildlife species, have lost a great deal
of natural habitat to development. Some species have been able to
adapt to habitat loss by moving into man-made structures. Female
bats of some species will roost in large colonies when they have
their pups. The potential of exterminating large numbers of bats at
once means that bat populations are particularly vulnerable to
extirpation.
White Nose Syndrome
White Nose Syndrome (WNS) is named for a white fungus that has
been found covering the muzzles and wings of hibernating bats in
the eastern part of the United States. More than a million
bats with WNS have died.
No cases of WNS have been found in Florida, but WNS is spreading
and biologists now know that both bats and people can carry the
spores of the fungus.
Human health implications of WNS are not known, but there
is no indication that people have been affected by WNS from
exposure to the fungus or affected bats. Regardless, the
public should never handle sick, injured, or dead bats.
Learn
more about White Nose Syndrome and How to Report Bat
Die-Offs
Protecting Bats
It is illegal to kill bats in Florida in accordance with Florida
Administrative Code number 68A-4.001 General Prohibitions and
68A-9.010 Taking Nuisance Wildlife. The use of pesticides or
poisons for the purpose of harming, killing, or deterring bats is
prohibited in the state of Florida. There is one legal
registered repellent: naphthalene (also known as moth balls).
Unfortunately, moth balls are rarely effective or practical in
repelling bats from a structure.
When bats take up residence in a structure where they are not
wanted, the legal, safest, and most effective technique for getting
rid of them is a process known as "exclusion". Excluding bats from
their roost sites involves the use of a one-way device which allows
them to exit the structure, but prevents them from returning. After
the bats are gone, the device is removed and the entrance holes
into the building are sealed. Prior to excluding the bats,
any other potential openings the bats might use should be sealed,
including openings as narrow as ½ inch. Bat-proofing for most
structures involves a few simple, energy-efficient home
improvements such as applying caulking and weather stripping.
To ensure that all bats have exited, exclusion devices in
Florida legally must be used for four consecutive days before the
opening is sealed. Because insect activity slows during cold
weather, bats often become inactive and may not exit the
structure. In order to keep inactive bats from being
trapped inside of a structure, bat exclusion devices may not be
used if the National Weather Service forecasts four consecutive
days of the minimum temperature below 50 degrees Fahrenheit.
Exclusions cannot be conducted between April 16th and August 14th
because when the mothers fly out of the structure and can't return,
they are separated from their flightless young, leaving the young
bats trapped in buildings. No permit is required to exclude
bats from a structure between August 15th and April 15th, and more
information on the simple equipment needed can be found through the
Florida Bat Conservancy
and University of
Florida/IFAS.
How You Can Help Protect Bats
- Avoid disturbing maternity colonies or entering caves where
bats are roosting.
- Never shoot, poison, or otherwise harm bats.
- Be cautious when using insecticides.
- Use caution when trimming trees and Spanish moss to avoid
disturbing roosting bats.
- Do not attempt to handle bats without the supervision of a
professional.
- Bats are very delicate creatures and are easily injured if
handled.
- Handling bats increases the chance that you might be
bitten.
- Seek medical help if bitten by a bat.
- Construct a Bat House
- Bats are so effective at controlling insects that some people
attempt to attract bats with bat houses. You can find information
on constructing or purchasing a bat house at Bat Conservation International
and Florida Bat
Conservancy.
- Bats are a very important natural resource for Florida because
each bat can eat hundreds of insects, including mosquitoes and
agriculture pests, per night.
- Bat guano (feces) has been used for centuries as a nutrient
rich fertilizer and is still highly prized by gardeners.
- Support Bat Conservation!
- There are many bat organizations that need more volunteers and
support. Links to bat conservation organizations are
listed below.
Additional Information:
Bat Conservation Organizations
Image Credit: Chris Burney
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