Canada's rich waters are perfect habitat for fishing birds, but a "swimming" bald eagle spotted recently off the coast of British Columbia had local residents a little puzzled. The behaviour is only rarely seen – but after checking in with the experts, we have a solid explanation lined up.

The seafaring bird was filmed by local resident Cheryl Papove near her home in the village of Belcarra. A pair of bald eagles had been hovering near her dock when one of them reportedly opted to "take a dip".

"One flapped and flew away," Papove told CBC News. "As I watched, it did a dive bomb at the one in the water."

Many online commenters have suggested the birds were simply dive-fishing, but Louise Shimmel, executive director at the Cascades Raptor Center, thinks this is an unlikely scenario.

While many other fish-eating birds, including ospreys, can fully submerge during a hunt, eagles cannot take off from the water.

"When hunting, a bald eagle flies just above the surface of the water and dips a foot in to grab a fish," clarifies Shimmel. "If they grab a fish or bird or something too heavy to fly off with, they will end up swimming to shore, dragging their prey."  

The manoeuvre takes a lot of energy, and there's a high risk of death by drowning, so the raptors tend to avoid it whenever possible.

The eagle in Papove's clip actually tried to climb a nearby pylon before eventually giving up and heading for shore. After watching the footage, Shimmel suspects we're witnessing the aftermath of a territorial squabble – similar in nature to what caused this great horned owl to take a swim back in 2014.

"The eagle shown swimming is a younger adult," she says. "Notice the head is not yet fully white. My best guess is that there was a territorial altercation in the air, possibly they grappled, and ended up in the water."

Interestingly, Papove witnessed a similar swimming episode four years ago:

"It's really uncommon," Papove said. "The fact I saw it once ... I thought that was a once-in-a-lifetime experience. Then to see it yesterday – and see two of them – was so exciting."


Top header image: Howard Patterson/Flickr