Shrews use echolocation to interpret and navigate their environment

The northern short-tailed shrew is a tiny mammal that resembles a mouse-sized mole. With poor eyesight but powerful hearing, the tiny critter burrows underground to hunt for insects to feed its voracious appetite.

Finding bugs among the dirt requires some specialized tools. Gleason et al. investigated the nature of shrews’ ultrasonic calls, providing evidence that shrews may employ echolocation to interpret and navigate their environment.

It is rare for a terrestrial mammal to employ echolocation, and initially, it was unclear if shrews vocally produced the ultrasonic signals, or if it was a byproduct of their motion. However, many features differentiate echolocation from communication calls.

“Echolocation calls are incredibly short in duration compared to calls produced for other purposes,” said author Valerie Eddington. “They are also typically broadband, consisting of energy distributed throughout a wide range of frequencies. These characteristics are ideal for quickly gathering information on the environment, whereas longer, low-frequency calls are ideal for sending information longer distances, as you would expect with calls used for communication within and across species.”

None of those characteristics are exclusive to echolocation, so to understand how shrews use their calls, the authors placed them in an unfamiliar environment. As the shrews explored, they vocalized the ultrasonic calls. They even exhibited bat-like scanning behavior with their heads. The calls met the echolocation criteria.

“It is important to investigate how animals, including shrews, navigate their environment because that knowledge has the potential to advance human technology in the same way the study of bat and dolphin sonar has advanced our ability as humans to navigate and monitor our world,” said Eddington.

Source: “Acoustic behavior in the northern short-tailed shrew (Blarina brevicauda): Ultrasonic click production in a novel environment,” by Margaret Gleason, Valerie Eddington, and Laura N. Kloepper, Journal of the Acoustical Society of America (2023). The article can be accessed at https://doi.org/10.1121/10.0020071 .