Just past 8 a.m. on the National Elk Refuge and refuge manager Steve Kallin is navigating a sport utility vehicle modified with four tank track-like appendages toward a bustling herd of roughly 3,000 elk just west of Miller Butte.

It’s feeding time, and a tractor with a snowplow on the front dumps alfalfa pellets in a series of straight lines that grow slowly northward.

Just past the maintenance sheds, a mangy-looking coyote moves toward us. Instead of veering away from the noisy vehicle, the coyote walks right into the road. When I get out to take a picture, he circles around the back and moves close, like a dog hoping for a Milk-Bone.

Closer to the elk herd, a series of grey-white dots resolve into more coyotes. Roughly 15 of the scavengers sit patiently on the horizon waiting for their chance at the main attraction, a dead bull elk just a 100 yards in front of the advancing throngs of his live herd mates.

As we motor our way through snowdrifts, dodging concealed irrigation ditches, most of the coyotes back off to a respectable distance. The two that do stay arch their backs, tuck their tails between their legs, shoot us unwelcoming glares and continue feeding.

A dead elk on the refuge might normally raise questions about disease or starvation, but Kallin inspects the animal and says he looks too fit. Instead, the elk might have met his demise at the antlers of a larger male. Gorings aren’t common, but they do happen.

So far this winter, mortality rates on the refuge have remained exceptionally low. Cold weather has kept bacterial diseases such as brucellosis or hoofrot at bay.

Only 34 elk on the refuge have died as of Feb. 22, for a rate of about 0.4 percent. Compare that to 2006, when 104 animals died by the same date.

But, according to refuge biologist Eric Cole, the worst is likely yet to come. This year, because of heavy snows, 7,950 elk and 920 bison have settled in for the winter.

If each bison equals the body mass and eating power of 2.6 elk, that’s the equivalent of 10,342 elk on the refuge eating a total of 50 tons of alfalfa per day. Only two years, 1997 and 1956 had more animals.

“It’s the combined effect of both species,” Cole says of his worries. “We will have a hard time keeping the animals on clean snow as the winter progresses.

“And, we’re just beginning to see significant melting,” he said of the changing season. “It’s those wet conditions combined with manure accumulations that cause many bacterial disease problems.”

Whether there will soon be a die-off, “it’s really impossible for me to predict,” Cole said. “But I am concerned with this many animals on the refuge.”

Though most of the animals now subsist primarily on supplemental feed, the large number of ungulates also have a continuing impact on natural forage. This time of year it’s mostly woody vegetation that suffers including the cottonwood in riparian areas, what remains of the willow communities, and, to a lesser extent, the sagebrush plant communities on the north end of the refuge.

This winter, Cole says, is a good example of why wildlife managers with the National Elk Refuge, the Wyoming Game and Fish Department and Grand Teton National Park are trying to reduce the animal numbers to 5,000 elk and 500 bison.

“The refuge is going to have to work with Wyoming Game and Fish and other land management agencies to develop hunting strategy to reduce the number of elk and bison wintering on the refuge,” he said.

As feeding continues, Kallin steps out of the sport utility vehicle and ties a tow strap to the dead elk. Later, he will return and cut out it’s lymph nodes to test for chronic wasting disease.

As we tow the carcass toward an elk boneyard near the maintenance shed, coyotes follow, waiting for another crack at a good winter meal.

Cole says it’s scavengers like coyotes that could keep a check on at least some of the diseases that are likely to sprout up as warmer, wetter weather moves into Jackson Hole.

“I would say on average, scavengers are a benefit when it comes to reducing the risk of disease transmission,” he says. “They might potentially reduce the risk of brucellosis transmission by consuming aborted fetuses.”