Take a gander for mergansers’ return, but look fast

The flock of 30-plus common mergansers worked the edge of the rocky shoreline on an incoming tide, the first large group of mergansers to drop by this fall.

As they rounded the point of a finger cove, some paddled across the opening and formed a rough line while others edged into the cove. Suddenly there was a flurry of activity as they began to herd a school of small fish into shallower waters.

Some swam with their head partly submerged, looking for prey; a few did a short burst of running on water with wings folded. Others dove for fish with strong legs propelling them underwater, coming up with smolt-size ones snagged perpendicular to bills with backward-facing serrated edges.

A little juggling so that the head faced down the chute and a gulp meant satisfaction and a quick return to hunting. Occasionally space squabbles broke out between mergansers, punctuated by a lunge with a wide open bill.

Mergansers ride low in the water, especially when diving. The birds will compress their feathers to push out the air and reduce buoyancy to make it easier to stay under water.

Common, red-breasted and hooded mergansers consume more fish than any other ducks, although they won’t turn down mussels, crustaceans and other aquatic life if it’s handy.

Sometimes their herding efforts attract herons, although in this case it was a trio of gulls that stayed on the shoreline’s edge, seemingly unwilling to battle for space with ducks with a spikelike bill.

Washington mergansers are the 23-inch red-breasted, 25-inch common and 18-inch hooded varieties.

It’s easy to tell the males of the species apart, at least in breeding plumage. The head of the hooded merganser makes it an easy call. When the crest is up, it’s a vertically shaped head with a very large white patch; when the crest is lowered, the white still shows, but not as strikingly.

The red-breasted and common can be distinguished at a distance because the common will appear to be a black-and-white bird with a smooth head and white sides.

The red-breasted often appears to have a bad-hair day with its ragged-looking crest, and a reddish wash on its breast.

The females are tougher. The female common has a clearly delineated large white patch under its throat, but it and the red-breasted female have the bushy crest off the back of their heads; the red-breasted head is duller (or paler) than the common female.

Size matters with the female hooded merganser, because it’s clearly smaller than the other two females, without the white areas and with a dark, rather than orange, bill.

Common mergansers, according to Washington’s Christmas bird counts, may be slowly increasing in population. They are abundant in Puget Sound, the San Juans and the Strait of Juan de Fuca.

Common mergansers court in winter, then head inland in the spring to nest in a tree cavity 15 to 50 feet above the ground. Females often return to the same nest year after year. Hooded mergansers also nest in cavities; the red-breasted prefers ground nests.

She lays her eggs, the male leaves, the precocial chicks hatch, and a day or two later they leap out of the tree and flutter to the ground. A week later they’re good divers, but mother abandons them to molt long before they can fly.

Of the three, the red-breasted is one of the fastest flying ducks, clocked at 100 mph. And even under water, the mergansers are fast and agile on their way to dinner.

Snow Sports Expo: Winter can’t be far away because the annual expo is this weekend at Qwest Field Event Center in Seattle. Admission is $10, children under 12 are free. Hours today are 10 a.m. to 8 p.m.; Sunday it’s 10 a.m. to 6 p.m.

Columnist Sharon Wootton can be reached at 360-468-3964 or songandword@rock island.com.