The grizzly bears at Canada's Grouse Mountain have woken up from hibernation at the record earliest time because of the warm weather.

The team at the Grouse Mountain Refuge for Endangered Wildlife decided to open the den door for Grinder and Coola at the start of March after the warm weather had seen the bears stirring from their slumber.

A statement from 6 March said: The groggy bears emerged and checked out their outdoor hibernation yard, munched on a little bit of green grass, and then returned to sleep back inside the den.

"Grinder and Coola will slowly wake up more now over the next couple weeks as their 2015 winter dormancy comes to an end! If you are up on the mountain be sure to stop by and see if they happen to be out and about!"

However, six weeks later, the bears fully emerged after 139 days asleep. The two males – both aged 13 – weighed about 450kg (992lbs).

Ken Macquisten, refuge director and veterinarian, said: "We continue to be amazed that ... two male grizzlies choose to share their den together and can sleep so long without seeking nourishment."

The bears were introduced to Grouse Mountain in 2001 after being orphaned.

Photos of them emerging were released by the sanctuary:

hibernating grizzly bears
Hibernating grizzly bears at the Grouse Mountain sanctuary.Grouse Mountain
Grouse Mountain grizzly bears
Wake up sleepy bearGrouse Mountain
grizzly bear hibernation
Best pals Grinder and CoolaGrouse Mountain
grizzly bear hibernation
Big yawns after 139 days asleepGrouse Mountain
grizzly bear hibernation
Still a bit sleepyGrouse Mountain
grizzly bear hibernation
Not all there yetGrouse Mountain
grizzly bear hibernation
Who is that handsome man?Grouse Mountain
grizzly bear hibernation
Steady does itGrouse Mountain
grizzly bear hibernation
First dip of the yearGrouse Mountain
grizzly bear hibernation
Back to normalGrouse Mountain