DOW surveys, classifies big game

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State wildlife experts are riding a helicopter around Northwest Colorado, spotting elk from the sky and recording key demographic data that will be used to guide license sales in the fall.

The process is often referred to as a post-harvest count. But it's more of a survey, said Darby Finley, a terrestrial biologist for the Colorado Division of Wildlife. Finley works out of the Division of Wildlife's Meeker office.

"I hesitate to call it a count," Finley said. "It's just an estimate. It's not feasible to go out and census a population."

Instead of counting every head, Finley and the others who work with him sample several herds in a region and attempt to classify the animals into rough groups depending on age and sex. They do it by flying over the animals' known winter ranges, preferably after a recent snow.

"Ideally, we'd have good snow cover to count them because it makes it easier to see them," Finley said.

But even if the snow doesn't cooperate, the counting must go on. Soon, the bulls will be losing their antlers, which make them easy to pick out among the cows.

Earlier this month, Finley finished surveying the deer, which lose their antlers even sooner than elk.

Finley and his colleagues use low-level flying, which puts them "right on the deck to be able to observe the animals really well." They attempt to achieve a breakdown of herd demographics. They start by visually sorting out the bulls, cows and calves.

The bulls are further classified by age according to the branching of their antlers. Yearling bulls, or spikes, have antlers with no branching. Two-year-old animals have four points or less. Mature bulls have racks with five or six points, Finley said.

The survey yields an estimated ratio of each subgroup compared to the herd.

"We take that information and put it into population models," Finley said.

The computer models incorporate survival estimates, harvest data and population samples to predict the number of licenses that should be issued to meet harvest objectives the following season.

It doesn't take a computer model to know that the overall objective for elk herds in Northwest Colorado is population reduction.

"Here in these larger units, we're looking for a reduction of 25 percent from what's on the ground," said area wildlife manager Dan Prenzlow. He manages the DOW's Area Six, which includes all of Moffat County, most of Rio Blanco County, and parts of Garfield and Routt counties.

Prenzlow's area also includes the two largest elk herds in the state. The Be sars Ears herd is estimated to include 30,000 elk, and about 50,000 elk live in the White River herd, according to last year's figures, Finley said. In this context, "herd" refers to the elk in a given geographic area, not a contiguous group of animals.

The DOW uses a complicated set of factors to determine a herd's ideal size. The overall health of the herd, the health of the habitat, the preferences of locals and the degree of "opportunity" afforded hunters and outfitters are all considered, Prenzlow said.

Reducing herd sizes is difficult to accomplish. Bull elk are the most popular animal for hunters, but killing bulls does little to affect a herd's size.

"You can't reduce a population except by reducing the breeding population," Prenzlow said. "People like to hunt bulls, but it doesn't do much for your management, at least in terms of herd size."

In 2003, the DOW tried a novel approach to increase the cow harvest. It offered no over-the-counter bull elk licenses for several game management units north of Craig, but issued 2,000 licenses for cows in the same areas.

Even that approach may have little effect this year, when the overall harvest was down due to unfavorable weather conditions and the natural guile of the elk.

"Elk are notorious for going where the pressure is non-existent," Prenzlow said.

If heavy snow doesn't push the elk down from the high country, or if they find a plot of land unavailable to hunters, there's little that can be done in terms of management, Prenzlow said.

More licenses do not guarantee a higher harvest. As more hunters pursue the animals, the success rate declines.

Aside from managing for herd size, the DOW also watches dynamics within the herd, such as the ratio of bulls to cows.

On the western end of Prenzlow's area, in trophy-hunting units, the DOW is looking to establish 50 to 60 bulls for every 100 cows. Farther east, near Craig, the goal is 20 to 30 bulls per 100 cows.

Although hunters and outfitters might like the idea, Prenzlow says, "We're not trying to grow 80 bulls per 100 cows. You just can't do that."

Jeremy Browning can be reached at 824-7031 or jbrowning@craigdailypress.com

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