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Figure 14.—Arctic tern. The longest flight known for an individual bird was accomplished by an arctic tern that in 3 months flew from the coast of Labrador to the coast of southeastern Africa.
The arctic tern (Sterna paradisaea) is the champion "globe trotter" and long-distance flier (figs. [14] and [15]). Its name "arctic" is well earned, as its breeding range is circumpolar and it nests as far north as it can find a suitable place. The first nest to be found in this region was only 7½° from the North Pole, and it contained a downy chick surrounded by a wall of newly-fallen snow that had been scooped out by the parent. In North America it breeds south in the interior to Great Slave Lake, and on the Atlantic coast to Massachusetts. After the young are grown, the arctic terns disappear from their North American breeding grounds, and a few months later they may be found in the Antarctic region, 11,000 miles away. Until very recently the route followed by these hardy fliers was a complete mystery, for although a few scattered individuals have been noted south as far as Long Island, the species is otherwise practically unknown along the Atlantic coasts of North America and South America. It is, however, known as a migrant on the west coast of Europe and Africa. By means of numbered bands the picture is now developing of what is apparently not only the longest but also one of the most remarkable of all migratory journeys.
Judging by the evidence at present available, it seems likely that the arctic terns of eastern North America originally found their way here from the Old World, probably by way of Iceland and Greenland. Consequently when the time comes for them to migrate to winter quarters they do not go directly south as do the common (Sterna hirundo) and Forster's terns (S. forsteri), but instead, they fly back eastward along their ancestral route across the Atlantic to the shores of Europe and then go south along the African coast to their winter home; those that breed in the northwestern part of the continent, as in Alaska, probably migrate chiefly down the western coast, as the species is not infrequently reported on the coast of California and also on the western coast of South America.
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Figure 15.— Distribution and the migration of the arctic terns of eastern North America. The route indicated for this bird is unique, as no other species is known to breed abundantly in North America and to cross the Atlantic Ocean to and from the Old World. The extreme summer and winter homes are 11,000 miles apart, and as the route taken is circuitous, these terns probably fly at least 25,000 miles each year.
The evidence yielded by banding consists of only three definite cases, but their interpretation seems to permit but one conclusion: All three birds were banded as downy chicks, one on July 3, 1913, at Eastern Egg Rock, Maine,[3] and the other two at the Red Islands, Turnevik Bay, Labrador, on July 22, 1927, and July 23, 1928. The first was found dead in the Niger River delta, West Africa, in August 1917, while the Labrador birds were recovered near La Rochelle, France, on October 1, 1927, and at Margate, near Port Shepstone, Natal, South Africa, on November 14, 1928. The flight shown by this last record is the longest known, the trip, between 8,000 and 9,000 miles, being accomplished in less than 3 months.
[3] Recorded at the time of banding as a common tern, a natural error, as the downy young of common and arctic terns look almost exactly alike.
Probably no other animal in the world enjoys as many hours of daylight as does the arctic tern, since for these birds the sun never sets during their nesting season in the northern part of the range, while during their sojourn in the south, daylight is continuous. During several months of the year they have 24 hours of daylight and during the other months considerably more daylight than darkness.