Nombre en español: Garza Patiamarilla
Nombre en inglés: Snowy Egret
Nombre científico: Egretta thula
La garceta nívea (Egretta thula), también conocida como garceta nivosa, garcita blanca, garza dedos dorados, garza chica o chusmita es una especie de ave pelecaniforme de la familia Ardeidae propia de América.
Es nativa de América, desde Canadá a Argentina y Chile. Divagante en Islandia, Portugal, Sudáfrica, Reino Unido, Samoa Georgias del Sur y Sandwich del Sur.
El plumaje de un blanco puro de esta especie y las delicadas plumas que cuelgan de su cabeza, cuello y dorso, tienen justa fama por su belleza. Ambos sexos adquieren esta coloración al principio de la estación de cría, y erizan sus plumas para exhibirse en el nido. Fuera de esta temporada, es una garza pequeña blanca, de pico negro y pies amarillo brillante.Plumaje nupcial.
Suele vivir en manglares de aguas dulces o saladas. Se alimenta de día, correteando en busca de peces y pequeños animales. A veces hurga el fondo del agua con sus pies, para hacer salir a sus presas. Se reúne en grandes bandadas para dormir sobre los árboles, donde anida en colonias.
Se conocen dos subespecies de Egretta thula:
- Egretta thula brewsteri Thayer & Bangs, 1909 – Local de Estados Unidos al centro de Argentina y Chile, e Indias Occidentales.
- Egretta thula thula (Molina, 1782) – W Estados Unidos a Baja California y litoral NW México
Egretta thula fue descrita por Juan Ignacio Molina y publicada en Saggio sulla Storia Naturale del Chili. Nella stamperia de S. Tommaso d’ Aquino, pp. 235, 344, en el año 1782.Etimología
Egretta: del francés aigrette, una garceta.
Thula: epíteto del nombre mapuche del ave, trüla.Sinonimia
- Ardea thula (Molina), 1782
- Egretta candidissima (Gosse), 1847
- Ardea candidissima (J. F. Gmelin), 1789
The snowy egret (Egretta thula) is a small white heron. The genus name comes from the Provençal French for the little egret aigrette, a diminutive of aigron, «heron». The species name thula is the Araucano for the black-necked swan, applied to this species in error by Chilean naturalist Juan Ignacio Molina in 1782.
The snowy egret is the American counterpart to the very similar Old World little egret, which has become established in the Bahamas. At one time, the plumes of the snowy egret were in great demand as decorations for women’s hats. They were hunted for these plumes and this reduced the population of the species to dangerously low levels. Now protected in the United States by law, under the Migratory Bird Treaty Act, this bird’s population has rebounded.
Adult snowy egrets are entirely white apart from the yellow lores between the long black bill and the eye, black legs, and bright yellow feet. The nape and neck bear long, shaggy plumes known as aigrettes. Immature snowy egrets have duller, greenish legs.
Distribution and habitat
The snowy egret is native to North, Central and South America. It is present all year round in South America, ranging as far south as Chile and Argentina. It also occurs throughout the year in the West Indies, Florida and coastal regions of North and Central America. Elsewhere, in the southern part of the United States, it is migratory, breeding in California, Nevada, Utah, Colorado, Arizona, New Mexico, Texas, Louisiana and Mississippi. It is found in wetlands of many types; marshes, riverbanks, lakesides, pools, salt marshes and estuaries. It is not found at high altitudes nor generally on the coast. The snowy egret has occurred as a vagrant in Europe, in Iceland, Scotland and the Azores.
The birds eat fish, crustaceans, insects, small reptiles, snails, frogs, worms and crayfish. They stalk prey in shallow water, often running or shuffling their feet, flushing prey into view by swaying their heads, flicking their wings or vibrating their bills. They may also hover, or «dip-fish» by flying with their feet just above the water surface. Snowy egrets may also stand still and wait to ambush prey, or hunt for insects stirred up by domestic animals in open fields. They sometimes forage in mixed species groups.
Snowy egrets breed in mixed colonies, which may include great egrets, night herons, tricolored herons, little blue herons, cattle egrets, glossy ibises and roseate spoonbills. The male establishes a territory and starts building the nest in a tree, vines or thick undergrowth. He then attracts a mate with an elaborate courtship display which includes dipping up and down, bill raising, aerial displays, diving, tumbling and calling. The immediate vicinity of the nest is defended from other birds and the female finishes the construction of the nest with materials brought by the male. It is constructed from twigs, rushes, sedges, grasses, Spanish moss and similar materials and may be 15 in (38 cm) across. Up to six pale bluish-green eggs are laid which hatch after about 24 days. The young are altricial and covered with white down when first hatched. They leave the nest after about 22 days.
Fossils of the snowy egret have been reported from the Talara tar seeps of Peru and in Bradenton in Manatee County and Haile XIB in Alachua County in Florida, United States. The deposits were dated to the Late Pleistocene.
In the early twentieth century, the snowy egret was hunted extensively for their long breeding plumes that fashionable ladies wore on their hats. This trade was ended in 1910 in North America but continued for some time in Central and South America. Since then populations have recovered. The bird has a very wide range and the total population is large. No particular threats have been recognised and the population trend seems to be upwards, so the International Union for Conservation of Nature has assessed its conservation status as being of «least concern».