Of Moose, Ravens, and Memories of Sharp Teeth
Moose in the Lower 48 have it made. Take, for example, the moose that live in Grand Tetons National Park, a place with its headquarters in Moose, Wyoming. As in Alaska, moose there have plenty of lakes and rivers to hang in and around, and plenty of willows to munch. Unlike their Alaska cousins, moose in Grand Tetons don’t worry much about grizzly bears and wolves eating their babies—until they came trickling back in the last few years, those beasts had disappeared from the Tetons.
A scientist recently wondered how life had changed for moose when their main predators were gone. Would a moose a few generations removed from the last wolf still be afraid of a wolf?
Joel Berger of the University of Nevada, Reno, found in Alaska a good comparison to the Lower 48 moose. Here, wolves and grizzly bears are still a major part of a moose’s life. Berger compared calf survival from five moose ranges in Alaska to two in Wyoming. In the Susitna River drainage, four out of ten moose calves lived to their first birthday. At the worst site in Wyoming, nine out of ten calves survived the first year.
Berger used recordings of animal noises to notice the different reactions of Alaska and Wyoming moose. He and assistants, including Kevin White of the Alaska Department of Fish and Game in Anchorage, carried into the field a car stereo, a 12-volt marine battery, and a set of JBL speakers. When they set up in a good moose area, they played recordings of animal noises ranging from wolf howls to the roars of lions and “dummy” noises, such as the sound of water flowing.
As they played the tapes, Berger, White and others watched the reactions of adult cow moose. Recordings of raven talk grabbed the attention of the Alaska moose. Moose in Wyoming, while hearing the same raven squawks and shouts, rarely lifted their heads. Moose in Alaska, particularly those at a study site in Denali, popped their heads up and perked their ears when hearing ravens. Berger pointed out a possible association between ravens and predators—Athabascan hunters have reported following ravens to game animals, and predators may do the same. Biologist Bernd Heinrich suggests ravens evolved with wolves in his book Mind of the Raven. Ravens may have led wolves to animals, Heinrich wrote. After wolves killed caribou or moose, ravens feasted on the open carcasses.
Not all Alaska moose reacted the same way to the sound of ravens. Berger played his recordings on Kalgin Island, and the moose were not impressed. But then, the moose on Kalgin Island have a lot in common with the moose in Grand Tetons National Park. The 15-mile-long island, in Cook Inlet between the town of Kasilof and Mt. Redoubt, has a good number of moose, but no grizzly bears or wolves, possibly because tidal currents make a swim to the island too risky.
People stocked Kalgin Island with moose 40 years ago. The moose in Grand Tetons have been free of grizzlies and wolves for 50-to-75 years. Berger wondered why moose would respond less strongly to predator cues after 40 years, which is about eight-to-ten generations of moose. He thought moose might have remained “hard-wired” to the cues of ravens for a long time after the elimination of predators, but his study shows that changes in the web of life that include bears, wolves, ravens and wolves may not take very long.
