
Echolocation, or bio sonar, is a biological sonar used by various animals for navigation, foraging, and hunting. Echolocating creatures emit calls and listen for echoes to locate and identify objects around them. These calls can be frequency modulated (FM) or constant frequency (CF), with FM providing precise localization in cluttered environments and CF detecting prey movements using the Doppler effect in open spaces.
Echolocating species include toothed whales (odontocetes), some bats, and a few bird species like cave swiftlets and oilbirds. Prey animals have developed strategies to evade capture, such as avoiding predators and using ultrasonic clicks for echolocation jamming.
Ranging in echolocation is achieved by measuring the time delay between sound emission and returning echoes, with differences in intensity at each ear providing information about distance and direction. Unlike human-made sonars that use multiple narrow beams, animal echolocation relies on a single sound source and two ears.
Bat call frequencies range from 11 kHz to 212 kHz, with insectivorous bats using frequencies between 20 kHz and 60 kHz for optimal detection. Calls can be either FM sweeps or CF tones, and bats can adjust call intensity to avoid deafening echoes. Echolocation calls can last from under 3 to over 50 milliseconds, depending on the bat species and call structure.