Gray wolves get nearly one-third of their food from human-generated sources, such as garbage or predation on farm animals. What’s more, the animals’ increasing dependence on humans could result in behavioral and genetic changes that will eventually produce a new species, according to a recent study.
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The research, published last week in the journal Bioscience, is based on an analysis by scientists from the United States and Australia of data collected in a number of countries about the relationship between large predators and humans. Among the animals studied were black bears, lions, red foxes (in Israel) and gray wolves.
The study found that all the predators showed increasing dependence on humans for food. This dependence is the result of a decline in quantities of natural food and the spread of human habitations and infrastructure into natural areas. One prominent example is the lions in India’s Gir Forest, the only place in Asia where lions remain. These lions get all their food from the carcasses of animals raised by humans, and they have gotten used to the presence of people near them.
In Israel, the study focused on red foxes, and revealed that the animals had restricted their living area due to a permanent supply of food from human sources.
Wolves, the animals from which dogs were domesticated in the past, have become extinct in many countries. But in recent years, in part after gaining protected status, they have begun to repopulate large areas of Europe and the United States. In many cases they rely on remnants of animal carcasses or predation on sheep and cattle for food. It is believed that on average, worldwide, a third of what wolves eat come from human sources. In some countries, including Iran, Spain and Greece, wolves prey on domesticated horses, chickens, cows and sheep for most of their food.
According to the recent article, packs will grow smaller due to intentional culling to reduce damage to flocks, and together with dietary and behavioral changes, could result in genetic alterations.
It is also more likely that wolves will mate with other human-dependent canine species such as feral dogs, and, in North America, coyotes. Eventually such cross-breeding could produce a new species of dog.
Not all scientists agree with the conclusions of the article. In an interview with the journal Science, biologist Robert Wayne of UCLA said: “I doubt if we’re domesticating wolves that eat human-sourced food.”
He went on to explain that wolves don’t eat directly from garbage, which would really separate them from other wolves. Rather, species like coyotes are more likely to be domesticated due to proximity to humans, he said.
Research carried out in Israel recently, and which was presented this month in an international nature conservation conference at Sde Boker in the Negev, bolsters the theory that wolves are becoming increasingly dependent on humans.
In the study, by scientists from Tel Aviv University and the Israel Oceanographic and Limnological Research Institute in cooperation with the Israel Nature and Parks Authority, 28 wolves in the Arava Desert were fitted with transmitters to follow their movements. The study found that they remained for long periods near communities and agricultural structures. Research on wolves in the Golan Heights showed similar findings and that the animals prey on cattle for much of their food.
According to the article in Bioscience, close contact between humans and wolves might lead to extensive damage to the animals to protect domesticated species from predation. The reliance of wolves on human-sourced food, the article says, is a sign that the wolves’ ecosystem is in decline. More should be done, the scholars conclude, to support the populations of wild herbivores that are the wolves’ natural food.