But many species also listen for the lower frequency sounds produced by their prey, for example the rustling sounds prey makes as it moves through leaf litter, or the courtship songs of katydids. They use high frequency sounds they produce themselves (echolocation) to orient and hunt. Brock Fenton's book Bats.“Studies looking at bat species diversity and niche differentiation typically compare diets or foraging behavior,” said Inga Geipel, STRI Research Associate and Marie Curie post-doctoral fellow, and lead author of the study, “but we think that bats’ ability to sense different kinds of prey could play an important role in the high diversity of species we see in the tropics.”īats are well known for their sophisticated skill to use sounds to navigate their environment. For interested readers, an excellent resource is M. To truly understand the concepts and complexity of this subject is to begin to understand the amazing nature of these animals. Echolocation is a highly technical and interesting tactic. The large variation in sizes, shapes, folds and wrinkles are thought to aid in the reception and funneling of echoes and sounds emitted from prey. The external structure of bats' ears also plays an important role in receiving echoes. At this point, the ear is ready to receive the echo of an insect one meter away, which takes only 6 ms. The middle ear muscle relaxes 2 to 8 ms later. This contraction occurs about 6 ms before the larynx muscles (called the crycothyroid) begin to contract. For bats to listen to the echoes of their original emissions and not be temporarily deafened by the intensity of their own calls, the middle ear muscle (called the stapedius) contracts to separate the three bones there-the malleus, incus and stapes, or hammer, anvil and stirrup-and reduce the hearing sensitivity. A concentration of receptor cells in their inner ear makes bats extremely sensitive to frequency changes: Some Horseshoe bats can detect differences as slight as. The ears and brain cells in bats are especially tuned to the frequencies of the sounds they emit and the echoes that result. Most sounds bats emit fall beyond the range of human hearing. Bat calls are categorized according to frequency, intensity and duration. In general, echolocation calls are characterized by their frequency their intensity in decibels (dB) and their duration in milliseconds (ms).ĮEEKKK. These noises resemble the sounds made by hitting two round pebbles together. Even so, we can hear echolocation clicks from some bats, such as the Spotted bat (Euderma maculatum). These sounds are generally emitted through the mouth, but Horseshoe bats (Rhinolophidae) and Old World leaf-nosed bats (Hipposideridae) emit their echolocation calls through their nostrils: there they have basal fleshy horseshoe or leaf-like structures that are well-adapted to function as megaphones.Įcholocation calls are usually ultrasonic-ranging in frequency from 20 to 200 kilohertz (kHz), whereas human hearing normally tops out at around 20 kHz. A few species, though, click their tongues. Most bats produce echolocation sounds by contracting their larynx (voice box). Of the some 900 species of bats, more than half rely on echolocation to detect obstacles in flight, find their way into roosts and forage for food.Įcholocation-the active use of sonar (SOund Navigation And Ranging) along with special morphological (physical features) and physiological adaptations-allows bats to "see" with sound. They are one of the few mammals that can use sound to navigate-a trick called echolocation. This leaf-nosed bat uses sound waves and echoes-a technique called echolocation-to capture prey, such as crickets.īats are a fascinating group of animals.
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