Two years of study shows bears, not wolves, the major elk calf predator on northern range of Yellowstone
The results are now in for the second year of the causes of elk calf deaths on the Northern Range of Yellowstone. This is important because the elk population has declined by about half in the last ten years, and wolf critics put the blame squarely on wolves and a low elk calf survival rate.
The study, "Multi-trophic level ecology of wolves, elk, and vegetation in Yellowstone National Park" will last 3 years.
The first year showed that bears took more elk calves that wolves. This year's study gave the following figures.
44 elk calves less than 6 days were radio collared. 31 are now dead. Preliminary causes of death are 18 by bears (grizzly and black), 3 by wolves, 4 by coyotes, 1 by a golden eagle, 1 by either bears or wolves, 2 by unknown predators, and 2 by non-depredation causes.
Here is the breakdown from 2003. 51 elk calves collared. 34 died. 19 were killed by grizzly or black bears, five by wolves, three by coyotes, two by either bears or wolves, one by a mountain lion, one by a wolverine and three died from causes other than predators.
My conclusion is that there is high predation on northern range Yellowstone elk calves with far less than half surviving into fall, but the cause is mostly bears, not wolves. We should be careful generalizing this to locations where there the density and type of predators is different, and the land is not managed to keep it basically unmodified by human activity.
Copyright © 2004 Ralph Maughan
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