Clinical pharmacist Laura Keene, 57, spotted the bears while visiting the Arctic National Wildlife Refuge on the Barrier Islands, of Barter Island in Kaktovik Alaska. The two cute cubs wave for the camera: Keene, said: 'It was such a surreal moment for me as a photographer when I saw that wave movement.' After spotting a sleeping male polar bear close by, a second family of polar bears began to walk away from the area while this mother and her two cubs watched them leave. Adult males can attack and kill young polar bears and the protective mothers were consistently watching the male.

Keene was in a 22ft boat where she and a group of other people could watch and photograph the bears for up to six hours a day while dealing with temperatures as low as -4 degrees celsius. Keene, Mason, said: 'It was such a surreal moment for me as a photographer when I saw that wave movement. Though intellectually I knew it was simply the cub moving to keep his balance as he stood upright, I pressed the shutter desperately hoping that I could capture that scene in focus as our boat rocked and pulled away. That event, in the character of the setting, with the mounds of snow and the wintery-grey background, are the sort of thing for which you always hope to be in the right place.'

She added: 'That day, our bear guide Ketil Reitan scanned the islands and noticed two families of bears, each with a mum and two cubs. 'From a distance he could see unusual behaviour, the mother bears were occasionally standing. 'He navigated the boat to the area and when we arrived he saw the reason - there was a huge male polar bear sleeping nearby.

'Adult males have been known to attack and kill young polar bears, so the mums were protectively monitoring his activity, standing occasionally to see over the mounds of accumulated snow. We stopped at a distance, with the male out of our view, hoping to have the opportunity to photograph the momma polar bears as they stood. 'Picking up on their mothers' concern, the cubs were on alert, not playing or roughhousing as they usually do. 'We were photographing the other family of bears which were about 60m away from our boat, as that mum stood and the cubs watched her face for direction.

'We couldn't see it, but figured out later that the male was waking up and beginning to move. The nearer family started moving in our direction, away from the male, so Ketril began to move our boat away. I focused on the family in the distance and took this series of shots when I saw them standing and watching the other cubs with intense curiosity. Their behaviour at the moment this photo was taken differed from their usual playing or sleeping. They were all on alert, the mum was serious and anxious and the cubs curious and attentive.'