Stanley Tate on Birds
Fall migration has started
Late summer is a restless time for birds.
As the days get shorter, they are beginning to eat with fervor, anticipating the task before them.
Male songbirds have stopped singing from the treetops and have become more furtive, their melodies and posturing from conspicuous perches no longer needed for courtship and territorial defense. They are abandoning their summer diet of insects and gorging on fruit and grain, which are more easily converted into lightweight high energy fat.
Birds are in passage now, obeying the orders of nature without knowing it.
Late summer is also a time for transformation as young birds fledge from the nest and breeding season ends. The young birds become more independent and roam about in their immature plumage. Meanwhile, adult birds shed their feathers, some undergoing striking changes in appearance. Birders encounter more plain-looking birds now than at any other time of the year.
They will leave soon. No matter the dangers that await them, they have only one option – to fly in autumn, the beating of their wings and the path of their flight determined by genetic mandate. Their journeys will begin at nightfall.
Every fall, 211 species of eastern North American land birds will travel up to 5,000 miles from places as far north as the forests of Canada to points as far south as the pampas of Argentina – most for the first time, many for the last time. Scarlet and Summer Tanagers will lift off from north Georgia bound for the evergreen forests of the Andes, and Bobolinks will leave North American grasslands for the marshes and grasslands of Argentina. The migration will swell each night as warblers, vireos, flycatchers, and thrushes go south to winter among Opal-crowned Tanagers and Blue-crowned Motmots.
As the migratory momentum increases, millions will stream overhead – orioles, tanagers, thrushes, vireos, warblers, grosbeaks, buntings, and others – funneling southward along the East Coast of the United States and through the Midwest to Texas and the North Gulf Coast. They stop along the way to rest and refuel, usually at safe areas like McIntosh Reserve and Kennesaw Mountain, but many times at less hospitable places because of bad weather or fatigue.
You can find them at daybreak as they land and disperse to sheltered places to rest and eat. Some will go on at sundown and others – the less fit and the young birds – will linger for several days where food is abundant and there is good shelter from predators.
At land’s end they have two options: follow the rim of land along the coast where Mexico and the United States connect or travel straight across the water to the Yucatan Peninsula and from there through southern Mexico and Central America south to their wintering grounds. All the while they are carried back to familiar summer places beyond the reach of frosts.