Artic terns are our most punctual spring visitors. Their arrival at the rookery near my house occurs somewhere between May 11th and May 13th each year. They can’t afford to be casual, because they are on a tight schedule. These beautiful, little birds that are distant cousins of gulls have one of the longest migrations of any animal. How far they travel is still not certain, but they fly at least from Alaska to Antarctica and back in a year, a distance of 25,000 miles (40,234 km). Only the sooty shearwater has a migration as long, or perhaps even longer, than an arctic tern’s, since they travel between New Zealand and the North Pacific.
Another interesting fact about Arctic terns is that since they spend summers in Alaska during our long days and then fly to Antarctica for the summer there with the corresponding long days, this species spends more hours in daylight than any other animal.
Arctic terns are slim and graceful. They have the largest breeding range of any water bird in Alaska, nesting from Point Barrow in the north to the Southeastern Panhandle. An adult Arctic tern is gray to white in color. Its pointed beak and its legs are red, and it has a black patch over the head and forehead. It has webbed feet, long, gray wings, and a forked tail. Because of their long wings and forked tails, terns are very agile and can make sudden turns and even hover in place. They look much like swallows and are sometimes called “sea swallows.”
Soon after their arrival in Alaska in May, they choose mates and begin nesting. During mating, the male performs a “fish flight,” in which he carries a small fish in his bill and flies low over a female on the ground. If she notices him, she will join him in a high climb and flight. An Arctic tern’s nest is a simple, scraped, shallow depression in the ground with very little or no lining material. The female lays two eggs that are brown or green in color and are lightly speckled. Both parents incubate the eggs, which hatch in approximately 23 days. As soon as they hatch, the chicks quickly leave the exposed nest and hide in nearby vegetation. The parents bring the chicks small fish to eat for the next 25 days, until the chicks fledge.
Less than three months after their arrival, by about mid-August here, terns leave their breeding areas and start their southward migration. It is interesting to watch the interaction between adults and their chicks when the young terns are just learning to fly. Because their webbed feet are small, terns don’t swim well. They hover over water until they spot a small fish and then dive into the water to catch it, but they don’t sit on the water, so young terns must learn to land on solid surfaces, which is tricky. Once a young tern lands, sometimes it is hesitant to take off again, and the adults will dive-bomb it until they force it to leave its safe perch. This behavior may seem harsh to an observer, but the adults must prepare the young Arctic tern for a 12,000-mile flight in the very near future.