Wolves howl to maintain social contacts, not because of stress, researchers have found.

Scientists at Austria’s Wolf Science Centre had wondered about the reaction of their animals when one is taken for a walk.

Typically, handlers took individual wolves out on a leash for long walks, one at a time. Whenever this happened, the pack-mates left behind always howled. To better understand why, the researchers measured the wolves’ stress hormones and collected information about status and relationships within the pack.

They learned that wolves howl more when a wolf they have a better relationship with, or one of higher social rank, leaves the group.

There was no link between the amount of howling and levels of the stress hormone cortisol.

The findings, published in the online journal Current Biology, indicate that social relationships better explain howling variation than wolves’ emotional states.

“Our data suggest that howling is not a simple stress response to being separated from close associates but instead may be used more flexibly to maintain contact and perhaps to aid in being reunited with allies,” said study leader Friederike Range, from the University of Veterinary Medicine in Vienna.