Nombre en español: Aguililla Tijereta
Nombre en ingles: Swallow-tailed Kite
Nombre científico: Elanoides forficatus
Foto: Edwar Guarín/Memo Gomez
Canto: Peter Boesman
El elanio tijereta (Elanoides forficatus), también conocido como gavilán tijerilla, halcón tijereta o aguililla tijereta, es una especie de ave accipitriforme de la familia Accipitridae, la única del género Elanoides. Se extiende desde el sudeste de los Estados Unidos hasta el este de Perú y el norte de Argentina, aunque casi todos invernan en América del Sur. En México recibe el nombre de milano tijereta.
El elanio tijereta mide de 55 a 65 cm de longitud, con una envergadura de 1,3 m. El macho y la hembra son similares. El plumaje es blanco y negro, muy contrastado. Las plumas remeras, la cola, las patas y el pico son negros. Se caracteriza por la cola ahorquillada, de la que recibe el nombre.
Los jóvenes tienen la coloración menos marcada, y la cola no está tan profundamente ahorquillada.
El elanio tijereta habita principalmente en bosques y humedales arbolados. Construye el nido en los árboles, generalmente cerca del agua. El macho y la hembra participan en la construcción del nido.
A veces emite un grito agudo; pero en general es un ave silenciosa.
El elanio tijereta se alimenta de pequeños reptiles e insectos, y bebe en vuelo rasante sobre la superficie del agua.
El apareamiento se desarrolla entre marzo y mayo; la hembra pone de dos a cuatro huevos. La incubación dura 28 días, y los polluelos abandonan el nido entre 36 y 42 días después.
Se reconocen dos subespecies de Elanoides forficatus:
- Elanoides forficatus forficatus – tierras bajas y litoral del sudeste de Estados Unidos y norte de México.
- Elanoides forficatus yetapa – del sur de México (excepto la península de Yucatán) hasta Brasil y noreste de Argentina.
The swallow-tailed kite (Elanoides forficatus) is a pernine raptor which breeds from the southeastern United States to eastern Peru and northern Argentina. It is the only species in the genus Elanoides. Most North and Central American breeders winter in South America where the species is resident year round. It was formerly named Falco forficatus.
Taxonomy and systematics
The swallow-tailed kite was first described as the “swallow-tail hawk” and “accipiter cauda furcata” (forked-tail hawk) by the English naturalist Mark Catesby in 1731. It was given the binomial scientific name Falco forficatus by Carl Linnaeus in the 10th edition of Systema Naturae, published in 1758; he changed this to Falco furcatus in the 12th edition of 1766. The latter spelling was used widely during the 18th and 19th centuries, but the original spelling has precedence. The genus Elanoides was introduced by the French ornithologist Louis Jean Pierre Vieillot in 1818. The name is from Ancient Greek elanos for “kite” and -oides for “resembling”.
Plate 72 of the Birds of America by John James Audubon, depicting the swallow-tailed “hawk,” or kite
The species is 50 to 68 cm (20 to 27 in) in length, with a wingspan of approximately 1.12–1.36 m (3.7–4.5 ft). Male and female individuals appear similar. The body weight is 310–600 g (11–21 oz). The body is a contrasting deep black and white. The flight feathers, tail, feet, bill are all black. Another characteristic is the elongated, forked tail at 27.5–37 centimetres (10.8–14.6 in) long, hence the name swallow-tailed. The wings are also relatively elongated, as the wing chord measures 39–45 cm (15–18 in). The tarsus is fairly short for the size of the bird at 3.3 cm (1.3 in).
Young swallow-tailed kites are duller in color than the adults, and the tail is not as deeply forked.
Habitat and behavior
The Swallow Tailed Kite is largely associated with large tracts of wetland forests which accommodates the birds nesting habits. Loblolly pines are the most prevalent choice for building nests but bald cypress (Taxodium distichum) are also used when the pines are unavailable. The major requirement of these nesting sites are food availability and tree height. Nesting locations are often found in trees as high as 100ft. Historic ranges in the United States covered the majority of the Southern states and much of the Midwest (As far north as Minnesota). Aside from the US, it resides in many areas throughout Central and South America. Habitat degradation and changes in wetland hydrology have caused the range to shrink in the US to just coastal regions of the southeastern and southwestern US, roughly an 80% decline in population. Swallow-Tailed kites are considered migratory raptors and during the spring months often move from areas in Central and South America to breed. Roughly 3% of the worlds population breed in the United States. Traveling thousands of miles these birds move towards the most suitable nesting habitat found within coastal wetlands between the Americas. Satellite-telemetry has allowed researchers to track movements of individual birds over the years and has yielded data that demonstrates some migration journeys longer than 10,000 miles. Land located within migration routes is thought to be another concern for the kites, as deforestation and habitat degradation in Central and South Americas can have adverse affects as the birds move to breed. The birds are considered one of the most graceful fliers seen in America and often spend the majority of their lives scouring high tree tops for lizards, small mammals, and insects. The morphology of the Swallow-Tailed kite’s wing and tail structure allows the bird to glide effortlessly for long distances.
Sometimes a high-pitched chirp is emitted, though the birds mostly remain silent.
The swallow-tailed kite feeds on small reptiles, such as snakes and lizards. It may also feed on small amphibians such as frogs; large insects, such as grasshoppers, crickets; small birds and eggs; and small mammals including bats. It has been observed to regularly consume fruit in Central America. It drinks by skimming the surface and collecting water in its beak. The bird usually does not break flight during feeding.
Mating occurs from March to May, with the female laying 2 to 4 eggs. Incubation lasts 28 days, and 36 to 42 days to fledge. Often thought to form monogamous pairs, the birds are thought to spend some time apart and meet up during migrations to nesting locations. These nesting locations are often found in the highest trees in wetland areas. On occasion, pairs will return to the same nesting locations of the previous years and refurbish old nests. Generally, nests take about four days to complete.
Conservation in the United States
Swallow-tailed kites are not listed as endangered or threatened by the federal government in the United States. They are listed as endangered by the state of South Carolina and as threatened by the state of Texas. They are listed as “rare” by the state of Georgia.
The Center for Birds of Prey in Charleston, SC has an ongoing effort to track sightings within the state. Anonymous reports can be made at https://stki.thecenterforbirdsofprey.org or by telephone. They will also send you the summary of the years reported sightings if you leave them your contact information.
Destruction of habitats is chiefly responsible for the decline in numbers. A key conservation area is the Lower Suwannee National Wildlife Refuge in Florida. As of 2016, populations have seemed to stabilize and even show increasing trends. Successful habitat restoration and management has allowed these birds to reestablish nesting populations on areas of Georgia, Florida, and South Carolina.