Summit Outside: Bats: feeding and value to agriculture |

Summit Outside: Bats: feeding and value to agriculture

Dr. Joanne Stolen
Special to the Daily
Special to the DailyPest control services provided by bats is estimated to save the U.S. agricultural industry as much as $53 billion.

Editor’s note: This is the second in a multi-part series on bats.

While some people consider bats creepy creatures of the night, they are clearly important to the environment and control of insect pests. The more we understand about bats the more we should admire them for their importance, and their remarkable characteristics.

They are not rodents, like mice or rats, and in fact some studies show that their intelligence aligns them more with primates or the monkey family.

Bats have extended communication skills and make all kinds of sounds to communicate. Researchers in the field have listened to bats and have been able to identify some sounds with some behaviors they demonstrate.

Emerging diseases and environmental changes affecting bats may be costly to the agriculture industry. Pest control services provided by bats is estimated to save the U.S. agricultural industry as much as $53 billion; money that would be spent on pesticides.

In temperate regions, like the United States, insectivorous bats consume enormous quantities of harmful forest and agricultural pests. An example is: the 150 bats in an average maternity colony eat in a season the following agricultural pest species: 38,000 cucumber beetles, 16,000 June bugs, 19,000 stinkbugs and 50,000 leafhoppers.

Larval cucumber beetles are the corn rootworms, and the elimination of 38,000 adult beetles would mean 18 million rootworms less. Studies have shown that a colony of approximately 20 million free-tailed bats at Bracken Cave, Texas, eat up to a quarter-million pounds of insects in a single night.

Think of how many more bug bites you would get if it weren’t for bats.

In the San Luis Valley, a bat colony consumes many tons of insects during the summer. A tiny bat may consume up to 3,000 insect per night, and mosquitoes are a common prey of a number of bats species.

Bats are found in almost every habitat available on Earth and different species select different habitats during different seasons.

They live seaside, here in the mountains and even deserts. Bat habitats have several basic requirements: they need a place to roost and spend the day; they need a place where they can hibernate in the winter, and they need a lot of food.

Most often they roost and hibernate in caves. Many also drink water and a high-speed camera has captured the bat’s method of skimming the surface of a body of water. It lowers its jaw to get just one drop of water, then skims the water again to get a second drop of water, and then a third, and so on, until it has had its fill. The precision and control is so very fine, it almost never misses.

Bats feed at night, and thus avoid competition with many daytime insect eating birds. They do however interact and compete with other nocturnal predators, such as nighthawks, swallows and swifts.

Some feed on ground-dwelling insects and arachnids, such as spiders, and might compete for food with scorpions, mice and shrews.

Bats are also important as part of the food chain, and are prey for snakes, owls and other raptors, ravens, jays, raccoons, foxes and skunks.

When bats are ready to roost in caves they often fly near the entrance apparently checking the time. One theory is that bats may be synchronizing their internal clocks with the solar cycle and to help time the activity cycles with other members of the population.

Bats are also essential to the environment of caves. Their droppings, or guano, provides nutrients which feed bacteria, insects, mice, rats and even fish. Without bats, caves are pretty much devoid of life. Their dung is so rich in nutrients that it is mined from caves in many parts of the world, bagged, and used to fertilize crops.

During the U.S. Civil War, guano was used to make gunpowder because it is high in nitrate. During the War of 1812, Big Texas Cave was mined for guano. During and after the Civil War, more than 100,000 tons of bat guano was mined for gunpowder and fertilizer from Carlsbad Caverns before they were designated as a national park. Even the Grand Canyon was mined for its guano deposits in the 1920s, and the droppings transported out on an aerial tramway.

In Thailand, it is valued as the best fertilizer available, and in the tiny region of Sarawak, Malaysia, the entire black and white pepper crop, which is about a third of the world’s supply, is fertilized with bat guano.

One species of bat which feeds on flowers has the longest tongue of any mammal relative to its body size. Some products pollinated by this species of bats, include kapok plant fibers for use in surgical bandages and life preservers, balsa lumber for crafts and designers’ models, sisal fibers for rope, chicle latex for chewing gum, agave juice for tequila and carob for candy and ice cream.

Not all folklore depicts bats as evil or scary. Chinese lore claims the bat is a symbol of longevity and happiness, and is similarly lucky in Poland, Macedonia, and among Kwakiutl and Arabs.

Pre-Columbian cultures associated bats with gods and often displayed them in art.

Three states in the U.S. have an official state bat: Texas and Oklahoma are represented by the Mexican free-tailed bat. Virginia is represented by the Virginia big-eared bat.

Breckenridge resident Dr. Joanne Stolen is retired from teaching microbiology at Rutgers University.

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