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More elk calves survive this winter

Elkhunter

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Herd numbers drop on Elk Refuge but increase in Gros Ventre.

By Rebecca Huntington

Although biologists counted fewer elk in the Jackson herd this winter, the survival of elk calves made a marked improvement compared to previous years.

Biologists counted 12,005 elk ­ down from 12,960 the previous year ­ in the Jackson herd, which Wyoming Game and Fish finished surveying last week. The state's population goal for the herd, which winters north of Jackson, is 11,000.

While overall herd numbers dropped, calf survival rebounded to a ratio of 28 calves per 100 cow elk. Biologists use cow-calf ratios to track the health of a herd.

This year's calf ratio is well above the 20 calves per 100 cows counted last year and the average from 1996 to 2001, which was 24.4. Low counts the past few years have been attributed to drought and predators, particularly wolves.

Although the drought persisted last year, "maybe things were a little bit more mild," said Doug Brimeyer, Wyoming Game and Fish biologist. Many factors play into calf survival, and it's impossible to pinpoint which factor is responsible for the rebound, Brimeyer said Monday.

Although calf ratios are higher this year that does not mean predators are not having an impact, he said.

In Buffalo Valley, biologists counted 29 calves per 100 cows, which is low compared to other native ranges, he said. Cows typically go to feed grounds while calves and yearlings tend to winter out on native ranges, he said. Thus, other native ranges had calf counts as high as 69, he said.

Elk wintering in the Buffalo Valley likely come from the Teton Wilderness where calves are exposed to higher densities of grizzly bears combined with wolves, he said.

"Most likely grizzly bears and wolves are having some impact on those localized [elk] herds in the Teton Wilderness," Brimeyer said. Research shows black bears and cougars also prey on calves, and other factors, such as accidents, can take a toll.

Also, other area herds logged higher counts. Elk on the South Park Feedground, for example, had a calf count of 38 per 100, Brimeyer said. That herd likely faced fewer predators than Buffalo Valley elk, he said.

But overall, calf numbers in the Jackson herd are looking up. A count of elk summering in Grand Teton National Park by park biologists this past summer also documented increased survival with 37 calves per 100 cows, up from 26 the previous year.

A good calf crop could translate into better bull numbers too, Brimeyer said.

"I think things are looking up for bull ratios in the years to come because we have the recruitment of the younger animals there," he said. "If we had another poor calf ratio we would see some problems."

Bull ratios increased slightly this year to 25 mature bulls per 100 cows, up from 24. There were eight spikes per 100 cows, the same as last year.

Meanwhile, overall elk numbers dropped on the National Elk Refuge this year with 5,876 elk on feed, down from 6,992 the previous year. The state and federal goal is to have no more than 7,500 on the Refuge. Elk wintering adjacent to the Refuge on the Bridger-Teton National Forest also dropped to 693, down from 740, Brimeyer said.

In contrast, elk numbers rose on three state-run feed grounds in the Gros Ventre River drainage. Wildlife officials counted 2,800 elk on feed, up from 2,500 last year. Also elk wintering next to the Gros Ventre feed grounds on natural winter range increased to 1,200 from 1,000.

The higher numbers in the Gros Ventre are likely due to more conservative hunting seasons, Brimeyer said. Game and Fish began backing off hunting pressure on that herd segment about three years ago, he said. Last year, the agency allowed only antlered elk, mature males, to be killed the last week of the season to protect cows, who are migrating to the valley floor, he said. Since a single bull will breed with multiple cows, controlling the numbers of females controls the overall population.

As Jackson elk numbers continue to dip closer to the state's population goal, Game and Fish likely will impose more conservative hunting seasons on other segments of the herd as well, Brimeyer said.

http://www.jhnewsandguide.com/Archives/Environmental/2004/040211-enviro.html
 
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