By Rebecca Morelle
Science reporter, BBC News
Remarkable new footage of Canada's Arctic wolves has been caught on camera by a BBC crew.
The team managed to film the wolves taking to the water to hunt waterfowl - behaviour that has never been seen before, according to an expert.
Arctic wolves live in the Canadian Arctic and northern parts of Greenland; observing them is a difficult task as they rarely interact with humans.
The team followed a pack on Ellesmere Island for several weeks last summer.
This glimpse into the lives of these elusive animals was filmed for the Natural World wildlife programme: White Falcon, White Wolf, which also features other animals, including gyr falcons, Arctic foxes and snowy owls, that live on the remote island.
Wolf expert David Mech, from the US Geological Survey, said: "I'd never seen wolves try to catch waterfowl before and this was interesting to see."
Usually, he said, wolves eat large hoofed animals, although they will vary their diet as circumstances dictate.
He explained: "They take advantage of whatever food opportunities are available, and in this case, these waterfowl were available, so they took advantage of trying to get them.
"I'm interested in the challenges these animals overcome to hunt their food. I've been intrigued with how the wolf manages to solve problems in so many different ways, with so many different species."
Ellesmere Island sits at the northernmost tip of Canada; it is only during the brief Arctic summer that the snow thaws to reveal the true features of the rugged landscape beneath.
Here, the BBC Natural History Unit tracked down a pack of eight wolves, including a dominant male and three one-year-olds.
Harry Hoskyns-Abrahall, assistant producer of White Falcon, White Wolf, said the team was lucky to come across the wolves almost as soon as they arrived on the island.
He told the BBC News website: "We went to this particular area because wolves had been spotted there a few years earlier.
"We were immediately encouraged when we found wolf tracks and marking posts on day one; and then the next day, we went out on the same route and we saw a wolf, which was absolutely unbelievable and very exciting."
By following the wolf and its tracks, the team was eventually able to track down a den.
"We were incredibly lucky," said Mr Hoskyns-Abrahall. "Once you've got the den, you have somewhere where the wolves are going to focus their behaviour."
THE ARCTIC'S WHITE WOLF
The Arctic wolf is actually a subspecies of the grey wolf
In comparison it has a shorter stature but a bulkier build
Scientific name for the Arctic wolf is Canis lupus arctos
It ranges across the Canadian Arctic and north Greenland
Packs will prey on caribou, musk oxen, hares, lemmings
The crew was able to film the animals going about their daily business.
"The most incredible part was when we saw the young wolf swim out to the middle of a lake and go after the geese, we just couldn't believe that it could seriously consider getting a goose in that way," he added.
The team was also amazed by the wolves' boldness.
"The younger wolves in the pack would come right up to us, and they would come up to our camp and empty our rucksacks - you would wake up and find your clothing spread all over the place. They were very inquisitive," explained Mr Hoskyns-Abrahall.
Arctic explorer Jim McNeill, who worked with the crew and kept a diary of his experiences for the BBC News website, was particularly taken with one young wolf who he nicknamed Lucy.
He said: "The highlight for me was one afternoon when the crew was off filming.
"Lucy came near the camp and I spent the best part of an afternoon with her in spectacular sunshine. We just shared a space - it felt extremely special."
He added: "I've been exploring this area for 25 years and to spend this time with these animals gave me another perspective on Arctic life.
Luck played a factor when tracking down the Arctic wolves
"To be part of the process of finding them and then capturing that footage was a fantastic feeling."
Fergus Beeley, producer of the programme, said making the film was something of an accomplishment.
He said: "Arctic wolves have been an aspiration [to film] of mine for about 15 years.
"I have a bit of a reputation for going for animals that are a tricky: filming the wolves posed the ultimate challenge.
"We didn't know where they would be 'denning', what their movements would be, so we had to do a lot of planning based on 'guestimates' - and luckily they worked out to be right."
White Falcon, White Wolf is on BBC Two on Friday 1 February at 2000 GMT and Sunday 3 February at 1755 GMT