A largest ever study of howling in the ‘canid’ family of species, which includes wolves, jackals and domestic dogs, has shown that the various species and subspecies have distinguishing repertoires of howling, or vocal fingerprints: different types of howls are used with varying regularity depending on the canid species.
Researchers say findings could help conservation efforts and shed light on the earliest evolution of our own use of language.
Howling is a behaviour commonly observed among a wolf pack. As pack animals, wolves work together to hunt and rely on howling as an important means of communication among each other. There are different explanations of a wolf s howl and it appears that there may be more to discover, Fred H. Harrington, a professor who studies wolf behaviour, said in an earlier study.
Researchers used computer algorithms for the first time to analyse howling, distilling over 2,000 different howls into 21 howl types based on pitch and fluctuation, and then matching up patterns of howling.
They found that the frequency with which types of howls are used — from flat to highly modulated — corresponded to the species of canid, whether dog or coyote, as well as to the subspecies of wolf.
The researchers made use of howls recorded from both captive and wild animals, from Australia and India, to Europe and the United States, creating a database of 6,000 howls that was whittled down to 2,000 for the study. This included combing YouTube for domestic dog howls.
Lead researcher Dr Arik Kershenbaum from the University of Cambridge describes these distinctive howl repertoires as resembling vocal dialects, with each species having its own identifiable use of the various howl types. He says the findings could be used to track and manage wild wolf populations better, and help mitigate conflict with farmers.
The origins of language development in humans are mysterious, as the vocalisations of our closest existing biological relatives such as chimpanzees are relatively simple. Kershenbaum and colleagues believe that studying the sounds of other intelligent species that use vocal communication for cooperative behaviour — such as wolves and dolphins — may provide clues to the earliest evolution of our own use of language.
Wolves may not be close to us taxonomically, but ecologically their behaviour in a social structure is remarkably close to that of humans. That’s why we domesticated dogs — they are very similar to us, said Kershenbaum, from Cambridge’s Department of Zoology.
The research was conducted by a team of scientists from the UK, US, Spain and India, and is published in the journal Behavioural Processes.
While the howling repertoires of most of the 13 species analysed were very distinct, some bore close similarities to each other that may influence interbreeding and, in at least one case, threaten the survival of a species.
Red wolves, hunted to the brink of extinction in the mid-20th century, were the focus of a reintroduction programme instigated by the US government, which has recently been halted due to a lack of success.
Part of the problem was red wolves breeding with coyotes, and the resultant hybridisation diluted attempts to maintain this rare wolf species. The researchers found significant overlap between the howling vocabulary of the red wolf and the coyote — with both favouring highly modulated, whining howls such as the one classed by researchers as ‘type three’.
Other conservation uses for the new findings may involve refining the use of playbacks to recreate more accurate howling behaviours that imitate territorial markings, thereby encouraging wolf packs to steer clear of farms and livestock.
For Kershenbaum, wolves and dolphins show remarkable parallels with each other in social behaviour, intelligence and vocal communication — all comparisons that extend to humans.