TERNS AND SKIMMERS ON THE WING
(Summer Bird-Life, Cobbs Island, Va. Am. Museum Nat. Hist., N.Y.)
“Notwithstanding this, something besides sight guides these travellers in the upper air. (Here is a route for you to trace on the map.) In Alaska, a few years ago, members of the Biological Survey on the Harriman expedition went by steamer from the island of Unalaska to Bogoslof Island, a distance of about sixty miles. A dense fog had shut out every object beyond a hundred yards. When the steamer was halfway across, flocks of Murres, returning to Bogoslof after long quests for food, began to break through the fog wall astern, fly side by side with the vessels, and disappear in the mists ahead. By chart and compass, the ship was heading straight for the island; but its course was no more exact than that taken by the birds. The power which carried them unerringly home over the ocean wastes, whatever its nature, may be called ‘a sense of direction.’ We recognize in ourselves the possession of some such sense, though imperfect and easily at fault. Doubtless a similar, but vastly more acute, sense enabled the Murres, flying from home and circling wide over the water, to keep in mind the direction of their nests and return to them without the aid of sight. It is probable that this faculty is exercised during migration.
“Reports from lighthouses in southern Florida show that birds leave Cuba on cloudy nights when they cannot possibly see the Florida shores, and safely reach their destination, provided no change occurs in the weather. But if meantime the wind changes or a storm arises to throw them out of their reckoning, they become bewildered, lose their way, and fly toward the lighthouse beacon. Unless killed by striking the lantern, they hover near or alight on the balcony, to continue their flight when morning breaks, or, the storm ceasing, a clear sky allows them once more to determine the proper course.
“Birds flying over the Gulf of Mexico to Louisiana, even if they ascended to the height of five miles, would still be unable to see a third of the way across. Nevertheless this trip is successfully made twice each year by countless thousands of the warblers of the Mississippi Valley.
“Probably there are many short zigzags from one favoured feeding-spot to another, but the general course between the summer and winter homes is as straight as the birds can find without missing the usual stopping-places.
Accidents during Migration
“Migration is a season full of peril for myriads of winged travellers, especially for those that cross large bodies of water. Some of the shore-birds, such as Plover and Curlew, which take long ocean voyages, can rest on the waves if overtaken by storms, but woe to the luckless warbler whose feathers once became water-soaked,—a grave in the ocean or a burial in the sand of the beach is the inevitable result. Nor are such accidents infrequent. A few years ago on Lake Michigan a storm during spring migration piled many birds along the shore.
“If such a disaster could occur on a lake less than a hundred miles wide, how much greater might it not be during a flight across the Gulf of Mexico. Such a catastrophe was once witnessed from the deck of a vessel, thirty miles off the mouth of the Mississippi River. Large numbers of migrating birds, mostly warblers, had accomplished nine-tenths of their long flight, and were nearing land, when they were caught by a ‘norther’ with which most of them were unable to contend, and, falling into the Gulf, were drowned by hundreds.
“Then, as I have told you before, birds are peculiarly liable to destruction by striking high objects. A new tower in a city kills many before the survivors learn to avoid it. The Washington Monument has caused the death of many little migrants; and though the number of its victims has decreased of late years, yet on a single morning in the spring of 1902 nearly 150 lifeless bodies were strewn around its base.