With its striking black and white plumage, deeply forked tail, and extraordinary aerial grace, the Swallow-tailed Kite is rarely misidentified as it courses low over the treetops in search of small vertebrates or twists and dives in pursuit of flying insects. Even at great distances, soaring Swallow-tailed Kites can be distinguished from Buteo hawks and vultures by their silhouette, slightly downcurved wings, and tendency to hang motionless while heading upwind. They rarely flap their wings but almost continuously rotate their tail, often to nearly 90 degrees, in order to hold a heading, turn abruptly, or trace tight circles while drifting across the sky.
The sexes are indistinguishable by plumage or size. The northern subspecies, Elanoides forficatus forficatus, breeds in the southeastern United States and winters in South America. The southern subspecies, E. f. yetapa, breeds from southern Mexico to south-central South America and is migratory at least in the northern portion of its range.
Gregarious in all seasons, this kite is a conspicuous inhabitant of wetlands in the southeastern United States, where it ranges over swamp and lowland forests as well as freshwater and brackish marshes. Several pairs, each apparently monogamous and producing a single clutch per season, may nest in close proximity. Extra, nonbreeding kites usually associate with nesting birds, whether solitary or in loose colonies. Although flying insects are the mainstay for this species during most of the year, nesting birds feed their young a diverse array of small vertebrates, including tree frogs, lizards, nestling birds, and snakes, which they glean from the tree canopy or emergent vegetation of marshes and ponds while in flight. Communal night roosts near nests are common, and premigration roosts may draw hundreds of kites from large areas.
The relative ease with which this kite can be observed in areas where it regularly nests and roosts belies the small size of its present U.S. population. The breeding range of this population (i.e., the northern subspecies, E. f. forficatus), which once covered parts of at least 16 (and perhaps as many as 21) states from Minnesota to Florida, presently includes portions of just seven southeastern states. Breeding habitat on publicly owned lands almost certainly is insufficient to ensure persistence of the population, but the lack of demographic data limits our ability to predict trends. Almost nothing is known of the biology, status, or conservation needs of the southern subspecies, E. f. yetapa, or of the migration routes and wintering destinations of E. f. forficatus .