Loons are no sitting ducks

Tom Spears, Canwest News ServicePublished: Friday, April 04, 2008
OTTAWA -- Loons, those serene emblems of peaceful wilderness lakes, are emerging in modern research as bloodthirsty attackers that drive out or kill their neighbours and take over the rivals' families.
And that lovely, haunting call? It's often a prelude to a fight. Sometimes a fight to the death, if one loon can dive under its rival and stab that sharp beak up into its heart.
It only looks like the same pair of loons returning year after year to the same lake, says professor Charlie Walcott of Cornell University.
Sure, that sometimes happens -- but it only lasts until an intruder lands on the lake, kicks out the resident male or female, and takes the loser's spot.
"Because loons look very much alike, you may not see the effects of the takeover that happened a week before you arrived," he said. "We only see it because our loons are all banded.
"You see the pair of loons gliding along peacefully. Most of the time, we don't see the effects of these intrusions. Mostly, I think, because we tend to get up later than the loons, and the intrusions tend to happen around daybreak."
Walcott's research comes from a couple of hundred small lakes in Wisconsin. He has watched loons for nearly 20 years along with biologist Walter Piper of Chapman University in California. Walcott studies neurobiology and behaviour and is dean of the university faculty at Cornell.
Here's how the hostile takeover works: A lone male or female flies over a lake and gives out a coded call -- a high, laugh-like sound that acts as a challenge.
The rival below answers, in a very different call. It's the more familiar loon call. Walcott calls it the yodel.
And the yodel contains information about the loon on the lake's surface. In particular, it shows the bird's weight (smaller birds have a higher pitch) -- crucial intelligence for the intruder if there's going to be a fight.
Sometimes, the intruder flies away. Sometimes it lands.
If it's a female, there can be a scuffle with the local female. The two birds beat each other with powerful wings and try to drown each other, but one bird inevitably gives up before either is killed.
Males, though, fight to the death in about 30 per cent of cases, in a savage fight that can last all day. For unknown reasons, he says, it's always the resident bird that is killed in these cases.
If the attacking male or female wins, it moves in to stay and takes over the mate of the defeated rival.
Loons can live 30 years, but they usually stay on one lake for about four or five years.
"It has been known that there were intrusions but nobody understood how it worked, so I think all of this is brand new," he says. His work is published in a science journal called Animal Behavior.