Albert Lee was out for a bike ride near the Country Hills Golf Course in northwest Calgary last Saturday when he came across a man trying to fight off an aggressive coyote.

"I heard screaming," Lee told CBC News on Friday.

"The screaming continued on for almost a minute. I looked around. I saw somebody trying to fight something off." 

Lee then realized it was a coyote that was trying to get at the man's dog and wasn't taking no for an answer.

"He was screaming. The coyote wasn't scared."

Lee was able to help the man and his medium-sized dog get to safety by using his bike as a shield at first, shaking it wildly, and then escorting them away from the area.

The city has closed two trails as a result of aggressive coyote sightings in the area, a parks department ecologist told reporters at a Friday news conference.

Coyote in NW Calgary park

Albert Lee said the risk he faced only started to sink in after he was looking at the pictures. (Submitted by Albert Lee)

Tanya Hope said it's denning season for the animals and coyotes often will move their pups between more than one den.

"If the den is close to the pathway, the coyote can be very aggressive," Hope said.

"They just want the space for their babies."

Hope says if you come across a coyote, "Don't run, be as tall as you can, be as loud as you can and back away."

Residents should call 311 with a specific location if the animal is aggressive, she adds.

Coyote in NW Calgary park

Albert Lee says he was shaking his bike between the coyote and another man's dog. (Submitted by Albert Lee)

Hope says homeowners in the area can help by keep their yards clean, especially animal waste.

"Pick up dog poo. It's like chocolate to coyotes," she said. 

Meanwhile, Lee says the risk he faced only came into focus after he was looking at the photos he shot.

"Only after I looked at the pictures, I realized I was in a dangerous position because the coyote has really sharp teeth. He could have killed any human being in an instant."