With more than 1,400 named species, bats make up 20% of the mammal kingdom worldwide. Bats are the only mammal capable of true flight. In fact, their taxonomic classification, order Chiroptera, translates to “hand wing”—their elongated finger bones are covered with skin and extend from their body to form a wing membrane.
The order Chiroptera is divided into two suborders, Megachiroptera and Microchiroptera (megabats and microbats). There are approximately 200 species of megabats throughout Africa, Australia, the Middle East, and Southern Asia. Megabats are generally large bats with large ears and small eyes that feed on fruit, pollen, and nectar. These bats locate food through smell and sight, unlike microbats which rely predominately on echolocation (using sound waves and echoes to locate food and other objects). There are more than 900 species of microbats throughout every continent except Antarctica. Microbats are generally small bats with small ears and large eyes that feed on insects, lizards, frogs, fish, birds, rodents, and blood.
Help Us Track Bat Colonies in Louisiana
Knowing where bats roost and how big their colonies are allows us to monitor the potential for the spread of white-nose syndrome into Louisiana and protect our important bat populations from this disease.
- Have a bat house or are installing a bat house
- Know the location of a roost (bats roost in trees or manmade structures due to lack of caves)
- Are interested in conducting acoustic surveys.
Diet and Foraging Behavior
Approximately 70% of bats are insectivores.
Most bat species feed on insects, fruit, nectar or pollen. However, some have a more varied diet. Three species of vampire bats are sanguivores, feeding solely on blood. All three species are found from Mexico south through Argentina. Unlike the common scene from horror movies, vampire bats do not bite and suck blood from human victims. Instead, they feed mainly on sleeping livestock—they use their incisor teeth to make tiny 3 to 5-millimeter incisions and then lap blood from the wound. Their saliva contains anticoagulant and pain-killing proteins which allow them to feed for about 20 minutes without the animal feeling their bite. These bats consume approximately 2 tablespoons of blood per day. Another bat species, the spectral or false vampire bat (Vampyrum spectrum), feeds on birds, rodents, and sometimes other bats, using scent to locate its prey. The seafood-eating bat (Myotis vivesi) feeds on small fish and marine crustaceans using its elongated feet and claws to capture its prey.
Bats are well-adapted to foraging in low to no light. Megabats primarily use sight and smell to find food in the dark. Microbats rely more heavily on echolocation, locating objects by reflected soundwaves. A bat produces a sound which bounces off an object in the environment and returns to the bat’s ears. The reflected sound allows bats to identify prey and capture it. Echolocation frequencies range from 20 to 200 kilohertz (KHz). Each species emits a unique frequency. As a result, scientists can use acoustic monitoring devices to record these different frequencies and identify a species’ presence and distribution without having to capture or even see an individual animal.
Role in the Ecosystem
Bats provide a number of ecosystem services, including dispersing pollen and seeds in tropical and desert climates and controlling pests. More than 500 species of plants, such as wild and cultivated varieties of bananas, peaches, and cloves, depend on bats for pollination. For example, long-nosed bats (family Phyllostomidae) are the primary pollinators of agave plants, which are used to make tequila. In tropical forests, members of families Phyllostomidae and Pteropodidae disperse seeds from hundreds of plants, including cashews, dates, figs, guavas, and papayas. Pollen and seed dispersal help maintain plant genetic diversity and aid regeneration of forests in disturbed areas.
Bats play an important role in controlling insect populations by feeding on hundreds of insect species. Bats eat mosquitoes which are known vectors of human and animal diseases such as West Nile virus and heartworm disease in dogs. Bats also eat a number of agricultural pests such as Asiatic oak weevil, corn earworm moth, cutworms, beet armyworms, cucumber beetle, green stink bugs, June beetles, and pecan nut casebearer moth. In fact, insectivorous bats save U.S. agriculture an estimated $3.7 billion dollars annually in pest control.
Threats to Bat Populations
Bats face many threats across their range, including changes in habitat, wind farms, bushmeat and souvenir trades, and disease. Habitat changes including degradation, fragmentation, and destruction reduce the quality and availability of bats’ roosting and foraging habitat. Wind turbines cause mortality for more than 20 species of migratory tree-roosting bat species in the United States. More than 160 species of bats throughout Asia, Africa, and Central and South America are hunted for human consumption and medicine. Additionally, bats are captured worldwide and preserved for sale as decorations and souvenirs. One of the largest threats to bats in the United States is the white-nose syndrome, a disease caused by the fungus Pseudogymnoascus destructans (Pd). White-nose syndrome has caused the death of more than 6.7 million bats since its discovery near Albany, New York, in 2006. In some locations the disease has resulted in 90 to 100% mortality in some areas where bats hibernate.