Wolves willingly foster cubs, a discovery that may help save rare wild wolf packs
Gray wolves were once common (credit: Edwin Giesbers/NPL)
Wolves have a certain undeserved reputation; gnarly, bitey, good for hunting down deer, farmers’ livestock and vampires, if you believe the movies.
But wolves have a softer, more social side, one that has been embraced by a heart-warming new initiative.
In a bid to save some of Europe’s last wolves, scientists have explored the willingness of these supposedly fierce creatures to help others of their kind.
They offered female wolves unrelated wolf cubs, to see how they would react. Not only did the females care for these lost cubs, they accepted them as part of the family.
Female wolves, the scientists have discovered, make excellent foster parents to wolf cubs that are not their own.
The study, published in Zoo Biology, suggests that captive-reared wolf cubs could be placed with wild wolf families, boosting the wild population.
Persecuted
The gray wolf (Canis lupus lupus) was once the world’s most widely distributed mammal.
But it became extinct across much of Western Europe and parts of the contiguous US, as a result of widespread habitat destruction and the deliberate persecution of wolves suspected of preying on livestock.
Fear and hatred of the wolf has since become culturally ingrained, fuelled by myths, fables and stories.
Wolves form strong social bonds (credit: Jeff Turner/NPL)
In Scandinavia, the European sub-species of gray wolf is endangered, the remaining population founded by just five animals. As a result, European wolves are severely inbred and have little genetic variability, making them vulnerable to threats, such as outbreaks of disease, they can’t adapt to quickly.
So Inger Scharis and Mats Amundin of Linkoping University, in Sweden, embarked on Europe’s first gray wolf-fostering programme.
They worked with wolves kept at seven zoos across Scandinavia. In all, eight wolf cubs were removed from their natural parents and placed with other wolf packs in other zoos. Thirty-five other cubs born during the programme stayed with their biological mothers.
The cubs were moved when between four and six days old, to ensure they have received their mother’s colostrum, or first milk.
Gray wolves are endangered in Europe (credit: Edwin Giesbers/NPL)
Not only did the foster mothers accept the new cubs placed in their midst, they moved their whole litter, including the foster cub, to a new den site, perhaps to better protect them.
The welfare of the foster pups, and the wolves’ natural behaviour, was monitored using a system of surveillance cameras. The foster pups had a similar growth rate as their step siblings in the recipient litter, as well as their biological siblings in the source litter.
What’s more, the foster cubs had a better overall survival rate, with 73% surviving until 33 weeks, than their biological siblings left behind, of which 63% survived, though this disparity had only marginal statistical significance. That rate of survival is similar to that seen in wild wolf cubs.
Wolf cubs are raised in dens (credit: US Fish and Wildlife Service)
Scientists believe that wolves can recognise their young, but this study suggests they can only do so once cubs are somewhere between three to seven weeks of age.
That leaves a window of opportunity in which fostering can work.
If captive-bred cubs can be placed with wild-living families, that already have cubs of a similar age, not only will they have a good chance of survival, but they could help dramatically increase the diversity of the wild population, say the researchers.
Just like the wild wolves they would join, these foster cubs would need protecting from persecution and hunting.
But their arrival could help preserve the future of one of nature’s most iconic, and polarising, animals.
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