SOURCE: The Guardian

DATE: August 25, 2019

SNIP: Biologists used to count over 1,000 head of elk from the air near Vail, Colorado. The majestic brown animals, a symbol of the American west, dotted hundreds of square miles of slopes and valleys.

But when researchers flew the same area in February for an annual elk count, they saw only 53.

“Very few elk, not even many tracks,” their notes read. “Lots of backcountry skiing tracks.”

The surprising culprit isn’t expanding fossil-fuel development, herd mismanagement by state agencies or predators, wildlife managers say. It’s increasing numbers of outdoor recreationists – everything from hikers, mountain bikers and backcountry skiers to Jeep, all-terrain vehicle and motorcycle riders. Researchers are now starting to understand why.

Outdoor recreation has long been popular in Colorado, but trail use near Vail has more than doubled since 2009. Some trails host as many as 170,000 people in a year.

Recreation continues nearly 24 hours a day, 365 days a year, said Bill Andree, who retired as Colorado Parks and Wildlife’s Vail district wildlife manager in 2018. Night trail use in some areas has also gone up 30% in the past decade. People are traveling even deeper into woods and higher up peaks in part because of improved technology, and in part to escape crowds.

The elk in unit 45, as it’s called, live between 7,000 and 11,000 feet on the pine, spruce and aspen-covered hillsides and peaks of the Colorado Rockies, about 100 miles from Denver. Their numbers have been dropping precipitously since the early 2010s.

Blaming hiking, biking and skiing is controversial in a state where outdoor recreation is expected to pump $62.5bn into the state’s economy in 2019, an 81% increase from 2014.

But for Bill Alldredge, a now-retired wildlife professor at Colorado State University, there is no other explanation. He started studying unit 45 in the 1980s in response to expanding ski resorts and trails systems.

To measure the impact on calves, he deliberately sent eight people hiking into calving areas until radio-collared elk showed signs of disturbance, such as standing up or walking away. The consequences were startling. About 30% of the elk calves died when their mothers were disturbed an average of seven times during calving. Models showed that if each cow elk was bothered 10 times during calving, all their calves would die.

When disturbances stopped, the number of calves bounced back.

“Generally when you ask people to stay out of the area no matter what the reason is, 80-90% obey you,” Andree said. “But if you get 10% who don’t obey you, you haven’t done any good.”

The recreation community acknowledges its impact on wildlife as well as other development, said Ernest Saeger, the executive director of the mountain trails alliance. Many people don’t understand the significance of the closures. Others, he acknowledged, just don’t care.