Heavy snow is tough going for wildlife in the winter months, and as a consequence this year, wildlife officials fear there will be a higher than normal die-off of elk calves this spring.

“It’s nature,” said Brad Weinmeister, a terrestrial biologist for Colorado Parks and Wildlife’s Durango office. “But the snow does stress animals out, and we do see higher mortality during high snow years like this.”

Elk spend the summer months fattening up in the high country of the San Juan Mountains. Around November, forage starts to disappear, and the animals must rely on and conserve their stored energy to survive the harsh winter months.

Most elk in the region, about 75 percent, tend to migrate down to lower elevations where there is less snow and it’s easier to move around, Weinmeister said.

A tracking study found that elk in the mountains around Pagosa Springs head south toward Navajo Reservoir or areas around the Jicarilla Apache Nation reservation near Dulce, New Mexico. Herds in the high country around Durango were found south of U.S. Highway 160, between Bayfield and Durango.

But even these lower elevation areas received a good deal of snow this winter, which means elk burn more calories moving around and trying to survive.

The herds can burn up so much energy, Weinmeister said, that they can’t recover even when food sources start greening up. It’s around this time that the “gas tank dries out,” he said.

And most at risk are elk calves.

“This year, we’re expecting a little more than normal (die-off),” Weinmeister said. “But we’re not expecting anything catastrophic.”

Elk populations have been in decline in Southwest Colorado for the past couple of years.

It’s an issue that experts say likely involves a number of factors, including complications from habitat loss, drought or perhaps some unforeseen disease.

But one issue – hunting pressure – is a hot topic of debate as Colorado is in the middle of restructuring its big-game hunting seasons.

Every fall, hundreds of hunters come to Southwest Colorado to scour the San Juan Mountains for big game. But this annual ritual happens to coincide with one of the most important times of the year for elk: mating season, known as the rut.

The rut, where elk compete for the right to breed, typically starts in mid-August. Breeding usually starts during the last week of September or first week of October.

This timing is important, allowing calves to be born in late May and early June, which gives the newborns enough time to bulk up before the winter.

David Petersen, who has been hunting in the mountains outside Durango since 1981 and studied elk under some of North America’s top experts, said the high number of hunters in the forest in September, as well as increased use of motorized vehicles and technology, have disrupted this process.

As a result, many calves are being born three to six weeks late, he said.

“A late-born calf doesn’t have time to put on body fat, gain strength and learn social skills, everything that’s necessary to survive their first winter,” Petersen said.

Petersen said he spends one to two months observing elk almost daily in the forest every fall, and he’s concerned about elk calf survival.

“I fear high calf mortality this year,” he said. “The late-borns don’t have a chance. We have to do something to take the pressure off the rut so that these calves are born on schedule.”

Coincidentally, this comes at a time when Colorado Parks and Wildlife is restructuring its hunting seasons. Many in the hunting community believe this is a crucial time when CPW can make changes that would relieve the elk of these pressures, not just in Southwest Colorado but statewide.

Danielle Isenhart, regulations manager for CPW, said the agency has conducted a robust public outreach over the past few months to hear hunters’ concerns and preferred solutions.

By far, the biggest topic brought up was the pressures of the hunting season in September, she said.

CPW will release in May a report that summarizes the public comment period. It will show what people were most concerned about, and what they’d like to see done about it. Such measures include limiting hunting licenses or spreading out the different types of hunting seasons.

Then, CPW staff will present in June its recommendations for the new hunting seasons to the Colorado Parks and Wildlife Commission, the board that will ultimately approve the restructured seasons, which would take effect in 2020.

“There’s lots of different options still on the table,” Isenhart said. “We’re still trying to figure out what’s best.”

CPW has a bit of a tight-rope act: The agency is tasked with providing hunting opportunities to the public, and hunting is a big economic driver for the state. A 2017 study estimated that big-game hunting seasons bring in more than $840 million to the Colorado economy.

But CPW must also protect animal populations, not just for hunters but for the sake of the environment and the species.

“The big issue is (late-born) calves, which is due to human disruption of the rut in September,” Petersen said. “That’s the drum I’m beating on, and I’m hoping CPW will finally do something about it.”

jromeo@durangoherald.com