Wolves in western Canada prefer to fish for salmon when it is in season rather than hunt deer or other wild game, researchers have found.
Scientists studied the eating habits of wolf packs in British Columbia.
Deer is the staple food of the wolves in the spring and summer but they often injure themselves hunting them.
When Pacific salmon return to the region's rivers to spawn in the autumn, the wolves prefer the taste of the more nutritious and easier-to-catch fish.
The researchers studied the droppings and hair of eight wolf groups over four years to discover what they ate.
They had expected the wolves to switch to salmon only if deer were in short supply but this was not the case.
"Selecting benign prey such as salmon makes sense from a safety point of view," wrote Dr Chris Darimont, from the University of Victoria, BC, and his colleagues in the journal BMC Ecology.
"While hunting deer, wolves commonly incur serious and often fatal injuries," the researchers said, adding that salmon fishing is much less time consuming than tracking deer in the forest."In addition to safety benefits, we determined that salmon also provides enhanced nutrition over deer, especially in fat and energy."