Bird of the Month - May 2003
 

Pacific Loon
Gava pacifica

by David Fix

For living things throughout the Northern Hemisphere, the time of year we call the month of May is flush with purpose, poignant in its hope and promise.  Winter is scarcely a memory, nor can summer yet be foreseen by those beings consumed by the irresistible urgency of procreation.  Across landscapes pulsing with the fever of the season, those which are alive rush to pass the baton, members of each nation striving to keep unbroken the string of generations.  Mid-spring touches the face of the waters as well. Along the eastern north Pacific coast and well out over the continental shelf, the ocean's surface now and again mirrors the fleet images of millions of northbound migratory birds, throngs headed in flocks, wedges, and individually to far northern nesting grounds.  For a period of a month or more, Pacific Loons typically dominate the migratory spectacle witnessed by birders watching the sea from shore points or on boats close to the coast.  This phenomenon is impressive.  More than one million have been tallied in passage in the course of a single season by an observer conducting daily seabird counts. 

Pacific Loons breed on lakes and ponds in n.e. Siberia, Alaska, and n.w. Canada.  Certainly the vast majority of their numbers are seen by but few humans in summer--nor in winter, when most of the population appears to retire to the Sea of Cortez.  It is during their annual spring migration from subtropical wintering grounds to the freshly-exposed wet wilderness of the tundra that we are able to admire their lean forms and white-spangled summer plumage.  Beginning in mid-April, flocks of these large waterbirds race northward near shore and over the comparatively shallow shelf waters.  Typically in early May, the floodgates are thrown wide open:  it is then that a birder armed with no more than binoculars and an ability to scan the horizon may see flocks of scores and hundreds pass any exposed coastal point.  A spotting scope brings even more into view.

These loons migrate in large, dispersed, open flocks, with plenty of space between each bird.  Because of this, the larger flocks (sometimes as many as a thousand) may occupy a great reach of sky, individuals flying both low over the water and quite high above it, seeming to fill the air with flashing wings.  Hours can pass, still the loons swarm past.  So many migrate past the Redwood Region that, although 99% of them may have disappeared to the north by early June, at least a few late stragglers can be spotted as late as the middle of the month!  The return movement of birds takes place mostly in October and November and is a more protracted, less conspicuous affair.  Surprisingly few of these hardy birds linger into mid-winter here.  Christmas Bird Count participants learn to train their scopes on the lee waters of headlands and jetties, where one or a few may associate with Red-throated Loons, Red-necked Grebes, and similar species.

Owing to distant views, poor lighting, and the birds' active diving, loon identification is a bit more involved than the straightforward accounts in the field guides may lead one to believe.  This is especially true for the duller, basic-plumaged or immature birds.  In winter, the Pacific Loon may resemble both the Common and Red-throated Loon, and practice is demanded in order to learn them well.  In their brilliant alternate plumage, however, they are distinctive.  The key points to notice are the eye-catching silvery crown and nape, black throat patch, and two rows of neat white spots along the shoulders.  Any flock of loons numbering in the dozens or hundreds will likely prove to be this species.