Two young bull moose in Canada took a dip recently. Not odd, you might say: moose in North America's vast boreal forest wade into lakes and ponds all the time to browse willows and slurp water lilies.

Yeah, fair enough – but these gawky adolescents got their hooves wet in the Arctic Ocean.

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Image: James Ruben/used with permission. 

Catching wind of the amphibious beasts this past Monday, James Ruben Jr, a resident of Paulatuk in the Northwest Territories, rushed to the shores of Darnley Bay and managed to snap a few pictures. Paulatuk lies about 100 kilometres (60 miles) north of the Arctic treeline.

"It's hard to believe, to see moose that close to the community!' Ruben Jr told CBC News.

The sight of a pair of bull moose up to their dewlaps in Arctic brine is unusual, for sure, but their appearance well away from the treeline has precedent.

For one thing, young moose often take extensive walkabouts. "The easiest explanation is that they are just curious animals," Trent University biology professor Dennis Murray told the CBC. "They are reaching those teenage years. They want to investigate their surroundings."

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Image: James Ruben/used with permission. 

What's more, moose have increasingly been spotted out on the barrens of Arctic Canada: along Coronation Gulf, for instance, and even on huge Victoria Island in the Canadian Arctic Archipelago (which, you should probably be aware of, may lay claim to the world's biggest island-in-a-lake-on-an-island-in-a-lake). The same trend has been seen in Arctic Alaska and Eurasia.

One limitation for tundra moose is the decreasing height northward of shrubs such as willows, which are both favoured fodder and also shelter. Stubbier shrubs don't protrude enough above the winter snowpack for moose to easily nibble them, and the animals may be more vulnerable to wolves where they can't seek cover in tall thickets.

A study last year, though, suggested that warming temperatures and a corresponding increase in both shrub extent and stature along tundra waterways may explain the northward expansion of moose in Arctic Alaska. The researchers estimated shrubs in the region were about 1.1 metres (3.6 feet) tall in 1860, compared with 2 metres (6.6 feet) in 2009. More (and taller) riparian shrubs means better year-round stomping grounds for moose.

And some modelling suggests that increased fires, longer and warmer growing seasons, and melting permafrost could boost shrub habitat along the taiga-tundra interface, expanding moose geographies at the potential expense of barren-ground caribou. 

(Then again, even as moose make climate-change gains on the northern frontier of their range, they're dealing with more diseases and parasites farther south that may be spreading under warmer temperatures.)

Meanwhile Ruben Jr took pleasure in the novelty of moose soaking in the Arctic bay near his town. "I love different animals," he told the CBC. "They are amazing to watch."