Zoo Blog

Thursday, April 7, 2011

A Pack of Ravens or a

Conspiracy of Wolves?

Written by: Zookeeper Maicie

While working in the wolf exhibit today, I could hear the low, hoarse, and incessant calls of ravens in the trees above. At the zoo, ravens and other birds commonly peruse the grounds for food, even stealing from our animals’ exhibits. What you may not realize is that wolves and ravens have a long and unique relationship that transcends their need for food. Many biologists believe that wolves and ravens have a bond that has evolved over millions of years.

Ravens, sometimes known as the "wolf-bird," have been observed circling a sick elk or moose and calling out, possibly alerting wolves to an easy kill. The wolf, in turn, kills the prey and opens the carcass, making the body accessible for the ravens to scavenge. Biologist Rolf Peterson reported that in the 27 years he spent observing wolves on Isle Royale, ravens were present at every wolf kill, often appearing within 60 seconds of the kill. Biologist Bernd Heinrich has observed similar behavior at Yellowstone National Park, but also noted that ravens may avoid carcasses where wolves are absent. Why wouldn't ravens take advantage of an easy food source? It fits a pattern Heinrich had observed before; that ravens invariably choose to be with the wolves. "Maybe [ravens] had evolved with wolves in a mutualism that is millions of years old, so that they have innate behaviors that link them to wolves, making them uncomfortable without their presence."

This seems to ring true when wolves and ravens also have social interactions outside of feeding. Biologists report seeing the two species playing. Ravens have been seen diving at wolves, like a game of tag, or sneaking up on a wolf and yanking its tail. Ravens even respond to wolf howls, resulting in a playful concert. It seems that our gray wolves have found their ravens, and you can find them both any day at the Lake Superior Zoo.