Oct. 31, 2010 While many people will be pursuing the latest pop culture icons as Halloween costumes this year, one of the annual icons of Halloween might be viewed as the Rodney Dangerfield of Halloween symbols. The legendary comedian based his career on the line "I get no respect," which might also apply to the misunderstood flying mammal known as bats. The animals often carry a negative connotation that doesn't reflect the respective role bats play in biological ecosystems.
Dr. Erin Gillam, a biological researcher at North Dakota State University, Fargo, conducts research on the role bats play in ecosystems around the globe, as well as on their ability to communicate.
Her research is designed to help understand how behavioral, ecological, and evolutionary factors influence the structure of animal communication signals. She has focused on investigating natural flexibility in bat echolocation and examining how bats adjust their calls in response to characteristics of their signaling environment. Most recently, information about her research was published in the Journal of Mammology.
Gillam has conducted field research on bats in Theodore Roosevelt National Park in the Badlands of North Dakota, in Texas and in Costa Rica. As part of her research, Gillam records bat calls through portable sensors, as well as capturing bats using mist nets. One aspect of the research, which is funded by the North Dakota Game and Fish Department, includes a statewide survey of the bat population in North Dakota to determine where they're foraging and roosting. Of concern is "white-nose syndrome," a fungal disease that kills hibernating bats. The disease is spreading in various areas in the U.S. Gillam's research team is also investigating the effect of wind energy on bats in North Dakota and the communication mechanisms of bats in Costa Rica.
"They're such amazing creatures," says Gillam. Bats use a natural type of sonar called echolocation to emit high frequency sounds that bounce off objects, which helps them determine the size, shape and direction of their prey, mainly insects, and other objects. "It's better than anything humans have come up with such as sonar," says Gillam. "It's an incredibly sophisticated sense that lets them build a picture of their surrounding environment."
Bats also use echolocation to navigate and find places to roost. Bats emit a loud sound, then measure the time it takes for the sound to bounce back, helping them determine how far away things are. Their echolocation can detect something as fine as a human hair in total darkness. Bats eat insects, including mosquitoes. In areas of the U.S., bats help agriculture by feeding on insects such as cutworms and corn-borer moths. They also pollinate more than 300 species of fruit.
Previous research by Gillam has shown that bats can quickly shift the frequency of their acoustic pulses, many times in only about one-fifth of a second. This allows them to avoid signal interference from other bats or noises. It's a type of built-in mechanism to avoid jamming of their communication signals.
Gillam and NDSU grad student Paul Barnhart are presenting initial results of their research at the North American Symposium on Bat Research in Denver, Colo., Oct. 29, in a presentation titled "Distribution, abundance, and habitat use of bats in North Dakota." In addition, Gillam is presenting "Effects of call structure on the jamming avoidance response in Brazilian free-tailed bats." NDSU grad student Lucas Bicknell and Gillam are participating in a student honors poster presentation on "Impacts of wind energy facilities on North Dakota bats: biological and social implications," regarding research which included Chris Biga, assistant professor of sociology.
Gillam notes that bats clearly get a bad reputation based on myths about them. She doesn't mind that her promotion of bat ecology sometimes results in the name Bat Girl. Even though she doesn't keep her car in a bat cave, she has been known to drive a gray pickup truck with "I love bats" on the license plate.
Bats: Myth vs Fact Myth: Bats are blind. Fact: They actually see better than humans. Their echolocation is a superior sense compared to sight, particularly at night.
Myth: Bats get caught in your hair. Fact: As you walk outside, you emit heat that attracts insects, which then attracts the bats that are looking for their next insect meal.
Myth: Bats are flying mice. Fact: Bats are mammals, not birds and not mice with wings. Their bodies are highly adapted and evolved for the specific life they lead.
Myth: Bats are a nuisance. Fact: Bats are important to ecosystems. Bats eat insects, including mosquitoes. A small brown bat can collect and eat anywhere from 600 to 1200 mosquito-sized insects in one hour. In areas of the U.S., bats help agriculture by feeding on insects such as cutworms, potato beetles, grasshoppers and corn-borer moths. They also pollinate more than 300 species of fruit. Bats are the only animal that naturally pollinates the agave plant which is used to create nectar and tequila.
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- Erin H. Gillam, Nickolay I. Hristov, Thomas H. Kunz, Gary F. McCracken. Echolocation behavior of Brazilian free-tailed bats during dense emergence flights. Journal of Mammalogy, August 2010, Vol. 91, No. 4, pp. 967-975 [link]
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