New technology lets scientists identify wild wolves by their howls

Jul 23, 2013 by Marcia Malory report
A wolf in Yellowstone National Park. Photo courtesy of Yellowstone National Park

Wild wolves play an essential ecological role, so researchers must be able to track them accurately. Unfortunately, because wolves travel over wide ranges, tracking them visually is very difficult. The ability to use sound to identify wolves would make wolf surveys much more reliable. PhD student Holly Root-Gutteridge and her team at Nottingham Trent University have developed software that enables them to identify individual wild wolves by their howls. The research appears in the journal Bioacoustics.

Wolves howl to protect their territories, contact other pack members and bond socially. They howl both individually and as part of a chorus, with howls overlapping one another. A wild wolf's howl, which is audible over at least ten kilometers, provides information about the wolf's identity. Tracking individual wolves by their howls would be more cost-effective than other tracking methods, such as the use of GPS technology.

A previous attempt to use audio sampling to identify wild wolves achieved an accuracy rate of only 75.7 percent. The scientists who performed this study analyzed the pitch of the howls, but not their amplitude. Root-Gutteridge and her team believe that the failure to examine amplitude caused the low level of accuracy. Recent studies of California sea otters, Australian sea lions and giant pandas have shown that including amplitude in sound analyses increases accuracy of identification.

To correct this problem, the team developed bespoke sound analysis software that included both frequency and amplitude in its algorithms. In an earlier study, they used this software to identify six captive eastern gray wolves by their howls. They were able to identify the wolves with 100 percent accuracy. While this study demonstrated the potential advantage of using this software, because it used wolves in captivity, it did not account for issues that arise when studying wild wolves, such as attenuation of sound over long distances and interference from environmental noises, such as wind and rain.

This video is not supported by your browser at this time.

In this later study, Root-Gutteridge and her colleagues used their software to analyze British Library recordings of wild eastern gray wolf howls, taken at unknown distances. The researchers studied 67 high-quality recordings of solo howls from 10 individual wolves and 112 low-quality recordings, which included both solo and chorus howls, from 109 wolves. Some of the low-quality recordings included wind and water noise. The researchers identified wolves howling on their own with 100 percent accuracy. They achieved a 97.4 percent accuracy rate when analyzing overlapping chorus howls, where the second wolf's howl began before the first wolf's howl ended.

The team suggests that bioacoustic researchers perform further studies on wolves in their natural habitats, examining how changes in distance and weather affect the ability to identify by sound.

Explore further: Scientists discover new 'transformer frog' in Ecuador

More information: Bioacoustics DOI:10.1080/09524622.2013.817317

Related Stories

Draft rule ends protections for gray wolves

Apr 26, 2013

Federal wildlife officials have drafted plans to lift protections for gray wolves across the Lower 48 states, a move that would end a decades-long effort that has restored the animals but only in parts of ...

Wolf hunting strategy follows simple rules

Oct 28, 2011

( -- A new study of wolves (Canis lupus) has found that communication between pack members and a social hierarchy are not essential features of a successful hunt, and all the wolves have to do ...

Endangered wolves at NY preserve produce 8 pups

May 08, 2012

(AP) -- Eight rare Mexican wolf pups have been born at a preserve in the New York City suburbs, a development that could aid the federal program that has reintroduced the endangered species to the wild.

Recommended for you

Scientists discover new 'transformer frog' in Ecuador

5 hours ago

It doesn't turn into Prince Charming, but a new species of frog discovered in Ecuador has earned the nickname "transformer frog" for its ability to change its skin from spiny to smooth in five minutes.

US gives threatened status to northern long-eared bat

8 hours ago

The federal government said Wednesday that it is listing the northern long-eared bat as threatened, giving new protections to a species that has been nearly wiped out in some areas by the spread of a fungal ...

Mice sing like songbirds to woo mates

8 hours ago

Male mice sing surprisingly complex songs to seduce females, sort of like songbirds, according to a new Duke study appearing April 1 in the Frontiers of Behavioral Neuroscience.

A new crustacean species found in Galicia

9 hours ago

One reason that tourists are attracted to Galicia is for its food. The town of O Grove (Pontevedra) is well known for its Seafood Festival and the Spider Crab Festival. A group of researchers from the University ...

Ants in space find it tougher going than those on Earth

10 hours ago

(—The results of a study conducted to see how well ants carry out their search activities in space are in, and the team that sent them there has written and published the results in the journal ...

Rats found able to recognize pain in other rat faces

11 hours ago

(—A team of researchers working in Japan with affiliations to several institutions in that country, has found that lab rats are able to recognize pain in the faces of other rats and avoid them ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 24, 2013
Really technology made life easier

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.