Bat Wings Are Unique As Human Fingerprints, Scientists Say

Bat wings might be as unique as human fingerprints, making their designs a reliable way scientists can track the animals.

A study in the Journal of Mammalogy describes how the network of collagen and elastin fibers that can be seen in the skin of a bat’s wing may be specific to each bat, potentially creating a method for identifying individuals in a population. Such a biometric system, which uses biological features instead of artificial means for this purpose, would be a less invasive way of distinguishing between bats than the artificial ones.

“Bat wing tissue is crisscrossed by what appear to be small lines; these lines are called collagen-elastin bundles, and they serve to make wing tissue strong but yet flexible enough for flight,” according to the U.S. Forest Service.

The researchers had examined several different kinds of bats, including little brown bats, northern long-eared bats, tricolored bats and big brown bats “to determine whether the ‘wing prints’ from the bundle network would satisfy the biologic measurement criteria.” Those criteria for an animal biometric system dictate that the features have to be distinctive, permanent and universal, and that the system should not kill the animals or change their behavior.

There are many biometric systems out there that rely on different biological features to get the job done. Those include patterns in an animal’s fur or feathers, or the arrangement of their whiskers.

“The ability to recognize individuals within an animal population is fundamental to conservation and management,” the study says.

Until this point, however, scientists have artificially marked bats to keep track of them — “techniques that may negatively affect the survival and alter the behavior of individuals.”

The Forest Service called bat identification a “ longtime problem in bat research.” The scientists do not want to interfere or influence a bat’s behavior, but there have not been any established non-invasive techniques of identification that are reliable.

In looking for a wing-based biometric system for bats, the scientists on this project studied photos of 230 bats taken over several weeks, to make sure they could consistently identify the same bats over and over using their wing features. The two people being quizzed on the bat identities were able to match most of the live bats in that group to their photos.

“This study suggests that bats can be successfully re-identified using photographs taken at previous times,” the researchers wrote. “We suggest further evaluation of this methodology for use in a standardized system that can be shared among bat conservationists.”

According to the Forest Service, a biometric identification system is particularly important in light of a deadly disease plaguing bats: white-nose syndrome. Millions of bats have died from this fungal infection in the last 10 years, potentially having negative effects on the environment because the bats that are vulnerable eat insects that would otherwise hurt crops and spread disease to others. The infection is called white-nose syndrome because bats that contract it have white fungal growths on their faces or wings.

Although the fungus affects bat wings, it does not take away the unique markings each bat has there.

“Bats are a major predator of forest and agricultural insects and are important to forest health,” Tony Ferguson, director of the Northern Research Station and the Forest Products Laboratory, said in the Forest Service statement. “This research is one of the ways that the Forest Service is advancing knowledge of an elusive species and contributing to the national effort to control white-nose syndrome.”