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

Report sick, unusually behaving or dead bats

 

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:

• Pallas's Mastiff Bat
• Jamaican Fruit-eating Bat

Bat Conservation Organizations

• Florida Bat Conservancy
• Lubee Bat Conservancy
• Bat Conservation International

Health of Bats

• White nose syndrome
• Bat Mortality Reporting

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Image Credit: Chris Burney