10 Animals That Use Echolocation

Scientists believe that these lucky animals have mastered the skill of biological sonar

Atlantic spotted dolphin in the waters north of Bimini, Bahamas
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Echolocation, or biological sonar, is a unique auditory tool used by a number of animal species. By emitting a high frequency pulse of sound and listening to where the sound bounces back (or “echoes”), an echolocating animal can identify objects and navigate its surroundings even while not being able to see.

Whether foraging under cover of night or swimming through murky waters, the ability to locate items and naturally map their environments without relying on conventional sight is a valuable skill for the following animals that use echolocation.

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Bats

Natterers bat flying through the forest
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Over 90% of bat species are thought to use echolocation as an essential tool for catching flying insects and mapping out their surroundings. They produce sound waves in the form of chirps and calls at frequencies typically above human hearing. The bat emits chirps at varying frequency patterns that bounce off objects in the environment differently depending on the object’s size, shape, and distance. Their ears are especially built to recognize their own calls as they echo back, something scientists believe to have evolved from the bat’s common ancestor, who had eyes too small for successful hunting at night but developed an auditory brain design to make up for it.

While a normal human conversation is measured around 60 decibels of sound pressure and loud rock concerts range around 115-120 decibels (average human tolerance is 120), bats frequently surpass this threshold on their evening hunts. Certain species of bulldog bats, found in the tropics of Central and South America, have been recorded exceeding 140 decibels of sound pressure from just 10 centimeters from their mouth, one of the highest levels reported for any airborne animal.

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Whales

A sperm whale in Mauritius
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Water, which is denser than air and more efficient at transmitting sound, provides the perfect echolocation setting. Toothed whales use a series of high frequency clicks and whistles that bounce off surfaces in the ocean, telling them what’s around and what food is available to them even in the deepest of oceans. Sperm whales produce clicks within the 10 Hz to 30 kHz frequency range at quick intervals between 0.5 to 2.0 seconds during their deep dives (which can exceed 6,500 feet) in search of food. For comparison, the average human adult detects sounds up to 17 kHz.

There is no evidence that baleen whales (those who use baleen plates in their mouths to filter sea water and catch prey, such as humpbacks and blue whales) can echolocate. Baleen whales produce and hear the lowest frequency sounds among mammals, and scientists believe that even early evolutionary forms of the animals as far back as 34 million years ago could do the same.

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Dolphins

Atlantic Spotted Dolphins swimming in the ocean north of Bimini
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Dolphins use similar echolocation methods as whales, producing short broad-spectrum clicks but at much higher frequencies. While they typically use lower frequencies (or “whistles”) for social communication between individuals or pods, dolphins break out their higher pitched clicks while using echolocation. In the Bahamas, the Atlantic spotted dolphin starts with a low frequency ranging between 40 and 50 kHz to communicate, but emits a much higher frequency signal — between 100 and 130 kHz — while echolocating.

Since dolphins can only see about 150 feet in front of them, they are biologically set up for echolocation to fill in the gaps. Apart from their middle and inner ear canals, they use a special part of their foreheads called a melon and sound receptors in their jawbones to aid in acoustic recognition from half a mile away.

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Porpoises

Dall's porpoise, a species of porpoise found only in the North Pacific
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Porpoises, which are often confused with dolphins, also have a high peak frequency of about 130 kHz. Preferring coastal regions to open ocean, the harbor porpoise has a high frequency biosonar signal wavelength of about 12 millimeters (0.47 inches), meaning that the sound beam they project while echolocating is narrow enough to isolate echoes from much smaller objects. 

Scientists believe that porpoises evolved their hyper refined echolocation skills in order to elude their biggest predators: killer whales. A study on harbor porpoises found that, over time, selective pressure from predation by killer whales may have pushed the animal’s ability to emit higher frequency pitches in order to avoid becoming prey.

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Oilbirds

Oilbird or Guacharo on Trinidad island
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Echolocation in birds is extremely rare and scientists still don’t know much about it. The South American oilbird, a nocturnal bird that eats fruit and roosts in dark caves, is just one of two avian groups with the ability to echolocate. The oilbird’s echolocation skills are nothing compared to a bat or dolphin, and it is restricted to much lower frequencies that are often audible to humans (though still quite loud). While bats can detect small targets like insects, oilbird echolocation doesn’t work for objects smaller than 20 centimeters (7.87 inches) in size.

They use their rudimentary echolocation ability to avoid colliding with other birds in their nesting colony and to dodge obstacles or obstructions when they leave their caves at night to feed. Short bursts of clicking sounds from the bird bounce off objects and create echoes, with louder echoes indicating larger objects and smaller echoes signaling smaller obstructions.

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Swiftlets

Glossy Swiftlet (Collocalia esculenta natalis) in Australia
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A diurnal, insect-eating type of bird found across the Indo-Pacific region, swiftlets use their specialized vocal organs to produce both single clicks and double clicks for echolocation. Scientists believe that there are at least 16 species of swiftlets that can echolocate, and conservationists hope that more research can inspire practical applications in acoustic monitoring to aid in the management of decreasing populations.

Swiftlet clicks are audible to humans, averaging between 1 and 10 kHz, though double clicks are so quick that they are often perceived as a single sound by the human ear. Double clicks are emitted about 75% of the time and each pair usually lasts 1-8 milliseconds.

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Dormice

A small gray dormouse on a pumpkin
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Thanks to its folded retina and an underachieving optic nerve, the Vietnamese pygmy dormouse is completely blind. Because of its visual limitations, this tiny brown rodent has developed a biological sonar that rivals the likes of echolocating experts like bats and dolphins. A 2016 study in Integrative Zoology suggests that the dormouse’s far reaching ancestor gained the ability to echolocate after losing its sight. The study also measured ultrasonic vocalization recordings in the 50 to 100 kHz frequency range, which is pretty impressive for a pocket-sized rodent.

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Shrews

A common shrew (Sorex araneus)
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Small insect-eating mammals with long pointed snouts and tiny eyes, certain species of shrew have been found using high pitched twittering vocalizations to echolocate their surroundings. In a study of common and greater white-toothed shrews, biologists in Germany tested their theory that shrew echolocation is a tool that the animals reserve not for communication, but for navigating obstructed habitats.

While the shrews in the study didn’t change their calls in response to the presence of other shrews, they did increase sounds when their habitats were altered. Field experiments concluded that the shrew twittering creates echoes within their natural environments, suggesting that these specific calls are used to examine their surroundings, just like other echolocating mammals.

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Tenrecs

A lesser hedgehog tenrec (Echinops telfairi)
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While tenrecs primarily use touch and scent to communicate, studies suggest that this unique hedgehog-looking mammal also uses twittering vocalizations to echolocate. Only found in Madagascar, tenrecs are active after dark and spend their evenings searching for insects on the ground and low hanging branches.

Evidence of tenrecs using echolocation was first discovered in 1965, but there hasn’t been much concrete research on the elusive creatures since. A scientist by the name of Edwin Gould suggested that the species employs a crude mode of echolocation that covers a frequency range between 5 and 17 kHz, which helps them navigate their surroundings at night.

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Aye-Ayes

A rare aye aye in a tree in Madagascar
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Known for being the world's largest nocturnal primate and being confined to Madagascar, some scientists believe that the mysterious aye-aye uses its bat-like ears for echolocation. Aye-ayes, which are actually a species of lemur, find their food by tapping on dead trees with their long middle finger and listening for insects under the bark. Researchers have hypothesized this behavior to functionally mimic echolocation.

A 2016 study found no molecular similarities between aye-ayes and known echolocating bats and dolphins, suggesting that the aye-aye’s tap foraging adaptations would represent a different evolutionary process. However, the study also found evidence that the auditory gene responsible for echolocating may not be unique to bats and dolphins, so more research is needed to truly confirm biological sonar in aye-ayes.