MSU researcher shares study on wolf stalking, elk populations at symposium
By ROB CHANEY of the Missoulian | Posted: Friday, November 6, 2009 6:30 am |
We guessed right about how many elk wolves eat, but we may have miscalculated how many elk don't get eaten because they don't get born.
That's the conclusion of Montana State University researcher Scott Creel, who spent three years in the Greater Yellowstone Ecosystem. Since wolves were reintroduced there in the 1990s, some elk herds have shrunk by 40 percent to
60 percent, including one in Yellowstone National Park's northern range that went from 17,000 animals to about 6,500.
But it's not that wolves are killing them, Creel said. Rather, the pressure from constant stalking is forcing elk to watch more and eat less.
"Prey animal will do things differently to avoid being killed, and those things aren't free," Creel said. "Their diet changes. They're browsing more and grazing less, that is, eating woody plants instead of grasses. Their nutrition changes as a consequence. In measurements over three winters, we saw their energy intake go down. Pregnancy rates changed as a consequence, so calf-cow ratios dropped pretty dramatically."
Creel noted that his studies applied to Yellowstone and the surrounding mountains, where wolves have made elk their major food source. In the Northern Continental Divide Ecosystem of northwestern Montana, wolves have a more varied diet of deer and elk, and his results might not be repeated there.
Expanding the understanding of wolves and wildlife behavior is a major theme of a two-day symposium of the Society of Conservation Biology's Montana chapter, where Creel was the first speaker on Thursday. Friday's program will bring in researchers and government wildlife managers from Montana, British Columbia and Washington, D.C. Their topics include interactions between bears and wolves, effectiveness of wildlife highway fences, and how to apply science across international borders.
"The great thing about science is everybody gets to throw out their viewpoints," said Ed Bangs, U.S. Fish and Wildlife wolf program coordinator in Helena and one of Friday's presenters. "It isn't like, 'We got the answer - let's go home now.' "
One variation on Creel's research many are interested in is whether the same reduction in pregnancies and calf deliveries holds true for cows and sheep threatened by wolves. Ranchers in wolf-prone parts of Montana have presented anecdotal evidence that their herds are losing weight and pregnancies because of wolf harassment. But Bangs said wolves killing livestock make up less than 1 percent of the state's annual livestock loses.
Another study in play right now is Montana's first-ever wolf big-game hunting season.
Montana hunters have already filled the 12-wolf quota for Wolf Management Unit 3, which includes the Greater Yellowstone Ecosystem and most of southern Montana. As of Friday, they had shot 24 of the allowed 41 wolves in Wolf Management Unit 1, which covers northern Montana above Missoula, Great Falls and Lewistown.
Wolf Management Unit 2, the Bitterroot and Big Hole valleys of southwestern Montana, had 12 of its 22-wolf quota recorded. The season ends Nov. 29, but may be partially extended depending on how many quota kills are unfilled at that point.
In Idaho, the only other state in the continental United States with a big-game wolf hunt, one district has met its quota and closed. Five more of the state's 12 wolf districts have five or fewer wolves remaining in their quotas. The Idaho season ends Dec. 31 in most areas, but extends to March 31 in two remote districts.
Creel said one difficult aspect of wildlife behavior is whether what we see now is a short-term shift or a long-term trend. In the elk-wolf case, we don't know if elk will adapt new strategies to avoid wolves and recover their numbers, if wolf numbers will fall in conjunction with the shrinking elk herds, or if we've hit a new population balance with wolves on the landscape.
"We don't know what the steady state is," Creel said. "Some of these ecological cycles are a couple decades long."
Reporter Rob Chaney can be reached at 523-5382 or rchaney
@missoulian.com.
http://www.missoulian.com/news/local/article_e8bf996a-ca99-11de-b688-001cc4c03286.html
