What Is So Special About Bats?
Why study bats?
Biodiversity
Bats are the second most diverse order of mammals with about 1,400 species worldwide. Currently, there are 150 species of bats recognized in North America, including 138 that are found in Mexico, 47 in the United States, and 17 in Canada. NABat will focus on the 47 species that are found in the United States and shared with Canada or Mexico. In Canada, three species are listed by the federal government as endangered, one species is considered threatened, and another species is considered a species of special concern. In the United States, eight species or subspecies are listed as endangered by the federal government and one species is listed as threatened. In Mexico, three species are considered threatened and two species are provided special protection.
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Bats are important to the maintenance of healthy ecosystems and are considered to be good bioindicators for monitoring ecosystem health because of their longevity and their sensitivity to changes in their environment that may also affect many other organisms. Additionally, bats provide many benefits and services to humans. Because bats are active mainly during the night (nocturnal) many of their important benefits and services occur “under the radar.”
Insect Consumption
One of the most important services that bats provide is insect consumption. Approximately 70 percent of all bat species either depend exclusively or primarily on insects for food, and these bats consume large numbers of insects throughout the growing season. For example, colonies of Mexican free-tailed bats in Texas often contain over 1 million bats; the economic importance of their foraging has been estimated to save cotton farmers approximately $12.2 million a year in insect pest suppression. Other studies estimate that bats across the United States and other parts of the word save farmers billions of dollars each year by patrolling the dark skies and literally gobbling up tons of flying crop pests each night.
Photo credit: M. Tuttle
Photo credit: M. Tuttle
Pollination
Some species of bats are also important pollinators of native and commercial plants. Over 500 different types of tropical plants are pollinated by bats every year. For example, nectar feeding bats pollinate Agave tequilana, which is the principal component used in the distillation of tequila, an economically important product of Mexico. These bats forage by plunging their faces down into a flower and using their very long tongues to lap up nectar stored there. While they are doing this, pollen becomes attached to their fur. Then when they visit other flowers, some of this pollen comes off, thereby fertilizing the flowers.
Seed Dispersal
Fruit-eating bats in the tropics and subtropics are important seed dispersers and aid in regenerating forests and fruit crops. When bats fly across nighttime landscapes, their combined abilities of digesting quickly and defecating ‘on-the-fly’ play an important role in regenerating clear-cut forests, especially rainforests. Bats also redistribute nutrients across the landscape. Bat guano is exceptionally high in nitrogen, phosphate, and potassium. Guano accumulations around the bases of bat roosts in dead trees fertilize the soil and may also aid in forest regeneration.
Photo credit: M. Tuttle
Medical Research and Treatment
Bats provide many other benefits to humans, some of which are just becoming known. They have served as important models in medical research, and compounds from their bodies are being used in new medical treatments. Because bats live much longer than would be expected based on their body size, they provide a good model for studies of the aging process, and studies of their metabolism have provided insight into some causes of aging. The transparent and extremely thin structure of bat wings have led to improved understanding of the dynamics of blood circulation in mammals. In other studies, a compound found in the saliva of the common vampire bat is being tested as a treatment for stroke victims, as it shows promise in providing faster restoration of blood flow with reduced risk of bleeding and can be administered later than other stroke treatments.
Biotechnology Research and Development
Bats have the most sophisticated flight mechanisms in all the animal kingdom. The structure and function of bat wings have been studied to understand the aerodynamics of complex flight. These studies are beginning to inspire engineered designs of futuristic aircraft, such as drones. In addition to fertilization, the components of bat guano may lead to future uses. The chitin from undigested insect shells found in bat guano may be used in pharmaceuticals, bioengineering, agriculture pest control, and textiles. The bacteria of bat guano, rich in ammonia, may someday be used in environmental engineering to remove nitrogen from industrial waste before it reaches our lakes and rivers.
Photo credit: M. Tuttle
Nightly bat emergences during summertime from daytime roosts in caves, tunnels, mines, or bridges provide impressive viewing opportunities as tens of thousands to millions of bats leave their roosts to forage for insects. Their collective flight can draw thousands of spectators, create interpretive opportunities, and provide economic benefits to nearby communities. For example, the emergence of Mexican free-tailed bats at Carlsbad Caverns or the Congress Avenue Bridge in Austin, TX, bring thousands of visitors to these areas. Total annual visitation to view Mexican free-tailed bats at these and 15 other sites in the southwestern United States was over 242,000 visitors, and their visits were conservatively estimated to bring in $6.5 million per year to the local communities.