Common loon's life is far more interesting than its name implies

Unlike most birds, which have hollow or air-sac-filled bones to create a weight easily moved by wings, loon bones are filled with marrow.

SHARON WOOTTON

Originally published October 23, 2001

Moments like this come by chance.

I had arrived home at dusk, but rather than unpack the pickup, I followed an urge to the point of land that juts out from the madrona-lined shore.

My instincts were rewarded by a pair of common loons, cutting through the water perpendicular to my position.

My bird calls are embarrassing, but since I was alone, I tossed out a tremolo call, a series of rising and falling notes.

The nearest bird made a 90-degree turn and looked in my direction with its red eyes. What the heck, I thought. I let loose again.

The bird started paddling directly toward me, aggressively (OK, so I'm overlaying my perception on a wild creature, but it's my story).

Aggressively, I say.

I took a step back and stayed still. The cartoon image of a loon attacking a birder filled my mind.

The loon stopped, still zoning in on my position. Having "scared away" the unseen "loon," it returned to its companion. They paddled away without another glance.

Loons are tremendously interesting. Unlike most birds, which have hollow or air-sac-filled bones to create a weight easily moved by wings, loon bones are filled with marrow.

Air-filled bones are tougher to keep under water, the loons' hunting ground. Marrow-filled bones' specific gravity is closer to water, thus it's easier to stay under.

The drawback is that there's more weight to move by wing, especially when their wings have the smallest wing-surface-to-weight ratio of any flying bird.

That's why loons, when sprinting and flapping along the surface of the water, wing tips splashing early in the run, look like they're one misstep from drowning.

The most likely of the five loons to be seen in the Puget Sound area is the common loon (Gavia immer), Pacific loons usually camping out in deeper ocean coast waters. While the most likely, they are not common in the sense of buffleheads or mergansers.

This is one of their wintering grounds, away from the ice-locked breeding grounds of the far north. Unfortunately, that means we miss all the bill-dipping courtship, dancing-on- water rituals and babies-on-the-back photographs.

When they arrive, most are still in their distinct, geometric-shaped black-and-white plumage, but molting soon turns that into shades of grays and whites for the winter. Molting leaves them flightless but not vulnerable because they can dive away from danger.

By compressing their feathers and forcing the air out, they can float with only their eyes and bill above the surface.

When diving for fish (crustaceans, frogs, occasional plant food), the missile-like loons usually stay down a minute or less and within 30 feet of the surface, but that's more convenience than pushing their limits.

Bird books usually give the outer limit as in the 200-foot range and the maximum time under water as 10-15 minutes.

Unlike a mallard, whose legs are more or less in the middle so that they can walk on land, loon legs are set far back on the body. That's great for propulsion under water, but walking is out.

The legs, ending in heavily webbed feet, extend outward to some degree when diving, creating an oarlike approach to paddling rather than the alternate-stroke that most ducks use.

The web collapses on the forward stroke to minimize resistance, then opens on the backward stroke to provide maximum force.

Physical dynamics aside, the loon's voice is the most appealing quality: hoots (short single notes), yodels (male only), wails (unbroken note or notes) and tremolos (loon laughter) that will stop most of us in our tracks.

Sharon Wootton is a free-lance writer from the San Juan Islands. E-mail questions, suggestions or comments about nature, or Nature's Journal, to songandword@rockisland.com.

The Olympian Copyright 2001

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