Zeus, an 11-year-old Maine coon cat, had a curious encounter with a young mountain lion.

The cats checked each other out — from opposite sides of a sliding glass door — about 6:30 p.m. Thursday in the Pine Brook Hills area of Boulder.

Gail Loveman, Zeus’ owner, said she was busy in the office of her home when she heard a noise and turned to see a young mountain lion on the porch.

“There was this cat 4-feet away from me!” Loveman recalled during an interview Tuesday.

That’s when Zeus entered the room and got into a stare down with the mountain lion. Another house cat, Bacchus, a litter mate of Zeus, peeked in but decided he was better off staying in the hallway out of sight, Loveman said.

Loveman, a volunteer firefighter with the Boulder Mountain Fire Protection District, grabbed a camera and started taking photographs.

The interaction between the cats went on for about 5 minutes.

Zeus typically stands tall, hisses and acts fairly aggressive when he sees other animals – mostly squirrels, other house cats or even dogs – through the glass door. But Zeus remained calm as he appraised the big cat.

“I think he thought ‘Hmmm! This is different,’ ” Loveman said.

When the lion left the porch, Loveman went to an upstairs balcony and spotted a second lion, which Loveman thought was likely the mother of the first lion.

She watched and took photos as the cats wandered off, jumped a fence and disappeared.

The Colorado Division of Wildlife describes the foothills of Boulder County as prime mountain lion habitat.

“We have a healthy population there,” said Jennifer Churchill, a division spokeswoman.

Still, human encounters with the secretive big cats are rare.

“People can live there their entire lives and not see them,” Churchill said.

Residents in lion country should take precautions to avoid potentially dangerous encounters, Churchill said, especially pet owners, and families with children.

Lions hunt prey to survive and should not be encouraged to visit, Churchill said.

People should safely try to scare wild animals off of their property, typically by making loud noises. Motion lights are a good deterent, Churchill said, and pets, even large dogs, should not be let out alone for long periods.

Churchill recalled an incident in which a lion killed a German shepherd and pulled it over a 6-foot fence.

“It’s rare, but it happens,” she said.

People should be deliberately noisy when they come and go from their homes, especially at dusk and dawn, prime feeding times for lions.

Loveman said she never felt threatened by her visitor last Thursday. She habitually takes measures to protect her house cats — they never go outside.

She had never seen a mountain lion prior to Thursday’s visit, and she hasn’t seen one since.

“The first cat looked at me but was clearly more interested in Zeus,” Loveman said. “The mother was clearly leery of me. I didn’t do anything to shoo them away.”

Loveman said she’ll be more aware of her surroundings when outside, especially around dusk and dawn.

Meanwhile, the thrill of the encounter remains fresh.

“I feel blessed.”

Kieran Nicholson: 303-954-1822 or knicholson@denverpost.com.