Arctic terns, champion long-distance flyers

Midsummer in Anchorage is a raucous time among the city’s lakes and along its coastal perimeters, as the eggs of songbirds, shorebirds, seabirds, and waterfowl hatch and avian offspring make the rapid transition from nestling to fledgling.

With families to watch and feed and protect, now is the brief but exhausting time of aggressive parenting. And among the water birds that seasonally inhabit Anchorage’s landscape, there is no more protective parent than the Arctic tern. They are fierce defenders of their young, as anyone who’s approached their nesting grounds can attest. Over the years I have seen them fearlessly attack gulls, ravens, humans, a northern harrier, and even a crane that came too close to nesting grounds.

Long fascinated by the ferocity and beauty of these amazing long-distance flyers, I once walked the Anchorage Coastal Wildlife Refuge’s sedge and mud flats, determined to seek further glimpses into the lives of Arctic terns.

Crossing a meadow of sedges, I skirted some ponds inhabited by several families of Canada geese, mallards, and American widgeon, while goslings and ducklings clustered about their parents on an early morning swim. Gulls screeched loudly as they circled and swooped above the ponds and their green perimeters, while families of violet-green swallows cut arcs through the calm air in their hunt for insects. In the distance, a fuzzy, gangly sandhill crane chick—already bigger than an adult goose--followed its parents, mimicking their slow, deliberate pace.

A hundred yards away or more, a couple of Arctic terns hovered over one of the small tidal guts that wind through the mudflats. I sat upon the bleached trunk of a cottonwood carried here by Cook Inlet tides and watched the terns through binoculars. They are such handsome, streamlined birds, which seem to carry themselves through the air with effortless grace on their slender wings.

Such flying talent is needed for their remarkable migrations. Arctic terns are the world’s long-distance flying champs; some members of their species make annual migratory flights between the high Arctic and the Antarctic, a round-trip distance of nearly 25,000 miles.

The evidence compiled by researchers suggests that terns take offshore, “oceanic” routes both north and south. Exactly where, or how often, they stop to rest or feed is largely unknown. In high winds they tend to travel low, right along wavetops; in calmer weather, they may fly hundreds of feet — and perhaps higher — above ocean waters.

Arctic terns leave Antarctica in March and begin to arrive in southernmost Alaska in the latter half of April. Researchers say they breed throughout the state’s coastal areas, from the southernmost Panhandle to the Arctic Coast, and west out the Aleutians. They breed inland as well, though their interior distribution is not as well documented.

According to Buzz Scher’s “Field Guide to Birding in Anchorage,” terns that spend their summers locally arrive from late April into early May. Mates will breed sometime in May and chicks hatch in June, reaching the fledgling stage in July. Most parents and offspring will then begin their southern migrations sometime between late July and mid-August.

While I watched the terns, one flew in and perched on a nearby piece of driftwood. This gave me an excellent opportunity to admire the tern’s sleek form, its black cap and striking blood-red bill and feet, which contrast so sharply with the white cheeks, neck and breast, the pale gray wings and back.

After several minutes, the bird lifted off and headed farther out onto the mudflats, where it joined another hovering tern. Mates, perhaps, engaged in hunting. I decided to follow. In a matter of moments, an alert was sounded. The two terns approached, yelling loudly in shrill, raspy voices.

Soon other terns joined the couple. I counted a handful, then 10, then a dozen. It seemed they had appeared out of nowhere. I must have been getting close—but to what? I can’t imagine that terns would try to raise a family out on the mudflats, where the inlet’s highest tides would swamp their nests. Research suggests that they will sometimes defend feeding territory. Is that what was going on?

My walk onto the mudflats was shortened when a pair of terns started dive-bombing me. Now uttering clicking sounds, the birds aimed straight for my head, then lifted or swerved at the last moment. Occasionally they swooped in close enough for me to hear the whoosh of their fast-moving bodies.

Arctic terns have been known to defecate on intruders and peck heads or hands uplifted to ward them off, sometimes drawing blood. In his pocket field guide “Alaska’s Birds,” author Bob Armstrong reported once being hit in the forehead by a tern. “It hit, drew blood, and made me more cautious,” he advised.

I quickly retreated back to the cottonwood. Almost immediately, the terns dispersed. Content to keep my distance, I scanned the coastal flats. Though some terns continued flying across the mudflats, others hovered above the pond, hunting sticklebacks and sculpins.

There is magic in the way a tern hunts. Hovering in place, with its long, forked tail spread wide for balance, the bird lifts its wings high above the body and beats them rapidly. Seen from below, the body is mostly white. And in that hovering whiteness, with the blood-red beak and black skullcap, the bird becomes a heavenly apparition.

If angelic, however, the tern is undoubtedly an angel of death. Sometimes hovering at 30 feet, other times just a few feet above the water, the tern zeroes in on its prey. Closing its wings, it then goes into a dive and plunges into the water with a splash.

Terns also feed by skimming the water, delicately picking prey at or near its surface. If successful at either plunge or skim methods, the bird emerges with a fish, or insect, or crustacean, which it quickly swallows—or carries to its mate or young.

There may be no better place locally to watch Arctic terns hunt and raise their families than Potter Marsh, where they can be observed from either roadside pullouts or the boardwalk. Through binoculars, I’ve watched terns circle and loop, heads down as they search for food. Finding it, they hover and dive, or skim gracefully across the water, opening and dipping their beaks.

On one memorable occasion, I watched terns lift from the water several times with small fish crosswise in their bills. Each time the birds circled and set down behind a wall of reeds. Were they feeding their families?

Seeking a different angle, I walked some distance along the Seward Highway. Sure enough, at my new vantage point, I saw two young terns perched on a log, 50 yards or more from the road. In between feedings, they preened their feathers, stretched and flapped their wings. From this distance, their plumage didn’t look much different than their parents’ and I wondered how close they were to flying.

The answer came a few minutes later when the fledgling terns joined their parents in flight. Aloft, the youngsters were clearly less streamlined than the adults. Their tails were shorter and less forked, their head caps a mottled black, and their bodies showed more grays and browns.

The fledglings returned to the log after a brief test flight. It would be a while yet before they were ready to hover and hunt.

The adults continued flying, looking for more food. And ever the protective parents, they would screech and dive-bomb and harass whatever stranger came too close to their young until the entire family was prepared to fly south together.

Anchorage nature writer Bill Sherwonit is a widely published essayist and the author of more than a dozen books, including “Living with Wildness: An Alaskan Odyssey” and “Animal Stories: Encounters with Alaska’s Wildlife.” Readers wishing to send comments or questions directly to Bill may do so at akgriz@hotmail.com.