Colorado wildlife managers and homeowners have killed at least 34 bears so far this summer, reflecting the bears’ growing reliance on human-derived food amid a seasonal shortage of forage in some areas.

This surge in what the managers call “lethal removals” builds on a pattern in Colorado, where people kill more than 1,000 bears a year. Hunters killed 1,051 bears in 2015 and 933 in 2016, Colorado Parks and Wildlife data show. Government wildlife managers and landowners kill additional bears deemed dangerous; last year, 334 bears were killed — 66 by state wildlife officials. At least 77 bears died last year when hit by vehicles.

Nobody is comfortable with what’s happening with bears, the largest surviving carnivores in the West. Some wildlife managers point to recent dry conditions and shortages of natural food that may be driving bears into cities. But there is evidence that some bears facing urbanization of their habitat are growing accustomed to eating human food in trash cans, campsites, cars and homes.

Even when natural foods are sufficient, about 32 percent of bears on Colorado’s Front Range still ate human food, a 2016 study led by CPW biologist Mathew Alldredge concluded. In western Colorado, 20 percent of bears still ate human food. The researchers analyzed hair and blood from bears killed by hunters to determine their diets.

“We’re receiving more reports of bears investigating people, getting closer to people than we normally would expect,” said Matt Thorpe, a CPW area wildlife manager in Durango (population 20,000), a stronghold for bears. “They’re not demonstrating that natural fear of humans that we usually see.”

Up to 50 people a day are calling the southwest regional office and reporting problematic bear behavior. In the Durango area, an early lush spring gave way to a June 10 freeze and hot dry spells, promising fewer forbs, acorns and berries.

A woman in Bayfield reported a bear chasing her children. She told CPW officials she yelled at the bear and tried to drive it away but that it kept following her kids. A federal contractor used dogs to track down and kill that bear.

In cases like this, public-safety priorities give wildlife managers little option but to kill bears, Thorpe said.

“Nobody gets into this line of work for that,” Thorpe said. “My darkest days as a game warden have been those days when I had to put a bear down — especially if it could have been prevented if people were more diligent about securing trash and other attractants.”

CPW officials say a late spring freeze and a dry July could limit the quantity and quality of forage for bears in some areas.

“… With higher human population densities, bears can be expected to encounter human food more often unless people change their personal behavior,” Lauren Truitt, a CPW spokeswoman, said in a statement. “The closer a bear, or bears, live to populated areas the more we will have human-wildlife encounters due to the easy source of food available.”

The agency estimates a statewide bear population of 17,000 to 20,000, but officials say that number is based on extrapolations and concede significant uncertainty. State wildlife managers have allowed increased hunting, issuing 17,000 bear-hunting licenses in 2014, up from 10,000 in 1997.

State wildlife biologists have established that bears adapt to use human food at least when necessary, and that females foraging aggressively to boost their weight are more successful reproducing when they eat human food.

The recent killings were done by CPW and federal contract wildlife managers. A few bears in the southwestern region were trapped and moved, but biologists say that strategy often fails if bears are moved to habitat occupied by other bears or if a bear already is strongly habituated to eating human trash.

Typically, bears confronted by humans back off. Those turning to human food sources typically are curious young males. CPW’s Thorpe said inquisitive bears increasingly may have had experiences moving with their mothers as cubs into urban terrain near people to find food — rendering them bolder than bears in the past.

Government wildlife managers and landowners killed at least eight bears in the southwestern area between Pagosa Springs and Cortez, CPW officials said. One bear had been eating chickens. Ten more were killed in mountainous areas to the east.

A CPW spokeswoman said 16 bears were killed in the northwestern Colorado, and a couple were killed in the northeast region that includes metro Denver and the booming north Front Range suburbs. One bear attacked a camper west of Denver who was sleeping outside a tent. The bear bit his head.

Traditionally at this time of year, bears forage for forbs and bugs. But they are opportunistic omnivores who find food wherever they can.

Colorado’s booming human population and expanding suburbs mean bears face more people more often, learning to locate human food in trash cans, in pet food bowls outside houses — and occasionally enter houses and cars.

Thorpe said at least four bears this month broke into homes near Durango. The homeowners responded. “Justifiably,” he said, “they shot the bears.”

This summer’s bear-human conflicts reflect complex dynamics that CPW researchers are studying. A recent bear-tracking project over six years around Durango reached conclusions expected to inform a smarter approach to bears. Among the findings:

• Bear-human conflicts do not necessarily mean the bear population is growing but that bears are adapting to take advantage of urban expansion.

• Bears that eat human food do not become addicted — contrary to long-held beliefs that have justified a two-strikes policy of euthanizing “food-conditioned” bears.

• Rising temperatures around dens and urban development in bear habitat shorten bear hibernation, leading more bears out more often, potentially increasing clashes with people.

• Colorado’s bear population could decline. In southwestern Colorado around Durango, where researchers studied 617 bears starting in 2011, the female bear population decreased by 60 percent.

“Coloradans do care about their wildlife, and we need their help to keep these bears wild. It is on all of us to do our part by taking simple steps like locking up trash, taking down bird feeders,” Truitt said. “If more people would be willing to secure their trash we could significantly reduce many of the encounters we face each summer.”