Singing For Your Supper: Echolocation for
Navigation and Prey Detection by Bats
 Dr. Winston Lancaster / CSU Sacramento 

Bats of the Suborder Microchiroptera use biosonar for navigation in darkness and many species also use biosonar to detect their insect prey. All bats of North America are included within the Microchiroptera and with the exception of three species confined to the southwestern deserts all species of the United States feed on insects. Biosonar, or echolocation, is accomplished when the bat emits a call produced in the larynx and detects the echoes that return from objects in the environment. Calls made by insectivorous bats are typically of high intensity, and usually descend from a higher to a lower frequency (frequency modulated calls). Of the 25 species of bats known from California, two species produce calls that are audible to most people. The remainder use calls that are above the frequency range of human hearing and are termed ultrasonic. These may only be detected with specialized electronic ultrasonic detectors. By using characteristics of the relationship between frequency and time, calls may often be identified to the genus of the bat or even to the species. Care must be taken, however, because bats vary the structure of their calls in relation to the environment. Calls also vary based on the proximity of the bat to a prey item. All insectivorous species produce calls characterized as search phase, approach phase and terminal phase as they forage for insects. Identification of species based on characteristics of echolocation calls must be approached cautiously.

Dr. Lancaster's research interests lie in the fields of functional and ecological morphology. His specific focus is on the morphological and physiological specializations by which the respiratory system of bats is adapted to power echolocation. He is currently an Assistant Professor in the Department of Biological Sciences at California State University, Sacramento. Professor Lancaster was an integral host of the 35th Annual North American Symposium on Bat Research held in Sacramento in 2005.

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