Nombre en español: Candelita Norteña
Nombre cientifico: Setophaga ruticilla
Nombre en ingles: American Redstart
Foto: Juan Carlos Noreña
La candelita norteña o pavito migratorio (Setophaga ruticilla) es una especie de ave paseriforme de lafamilia de los parúlidos que vive en América. Tradicionalmente era la única especie del género Setophaga, pero posteriormente se incluyó en él a todos los miembros del género Dendroica y algunos de Parula.
Los adultos miden una media de 12 cm de largo. Los machos son de color negro en la cabeza, las partes dorsales, la garganta y el pecho; el vientre y las plumas cobertoras de la cola son blancos. En los flancos del pecho hay manchas naranjas brillantes, también en las rémiges del ala y en la cola.
En las hembras, la cabeza y las partes dorales son grisáceas o grisáceo oliváceas, y las partes ventrales blancas. En los costados y la cola hay manchas amarillo limón brillante.
Los juveniles se parecen a las hembras pero los machos presentan tintes naranjas en los costados, además de presentar algunas manchas negras en el cuerpo.
Distribución y hábitat
Anida en Canadá y el norte y este de los Estados Unidos. Es una especie migratoria que invierna en el sur deCalifornia, México, en las Antillas, América Central y norte de Sudamérica.
Habita en el interior o el límite de bosques con abundante hierba o arbustos. Se alimenta principalmente de insectos, ya sea en solitario o en grupos; es muy activo, revolotea constantemente y abre su cola en abanico. Caza insectos en el vuelo.
Durante la migración habita en selvas tropicales, bosques secundarios deciduos y campos con abundante hierba.
The American redstart (Setophaga ruticilla) is a New World warbler. It is unrelated to the Old World redstarts.
The genus name Setophaga is from Ancient Greek ses, «moth», and phagos, «eating», and the specific ruticilla is New Latinfor «redstart» from Latin rutilus, «red», and New Latin cilla, «tail». «Redstart» refres to the male’s red tail, «start» being an old word for tail.
Distribution and habitat
Although perhaps not as common as in the past, this appears to be one of the most stable and abundant species of New World warbler, its numbers exceeded in total by the common yellowthroat, yellow warbler and yellow-rumped warbler, because of much wider natural breeding ranges in those species and perhaps exceeding those in sheer density within appropriate range. They breed inNorth America, across southern Canada and the eastern United States. These birds are migratory, wintering in Central America, the West Indies, and northernSouth America (in Venezuela they are called «candelitas»). They are very rare vagrants to western Europe. During the breeding season, this warbler inhabits open-canopy, mostly deciduous forests, second growth, and forest edge across much of the United States and southern Canada. This insectivorous bird often shares its foraging habitats with other warblers, and is found feeding in the mid to lower regions of a tree or shrub. A wide range of habitats are occupied during migration, including many shrubby areas. On their wintering grounds in Central and South America, this warbler may be found in nearly all woody habitats but tend to avoid non-forested agricultural areas. It is often found in shade-grown coffee plantations which provide native trees and shrubs, as well as coffee trees. Elevations occupied vary by location, as this species may be found at elevations up to 3,000 m (9,800 ft) in South America, but only up to 1,500 m (4,900 ft) in Jamaica.
The breeding habitats of the redstarts are open woodlands or scrub, often located near water. They nest in the lower part of a bush, laying 2–5 eggs in a neat cup-shaped nest. The clutch is incubated by the female for 10 to 13 days. The young fledge after 9 days in the nest, and may remain with one parent for up to 3 weeks after fledging. First-year males are able to reproduce during their first breeding season, but they retain the female-like plumage which may contribute to low reproductive success (less than 50% of first-year males) until year 2. In contrast, most first-year females successfully reproduce during their first breeding season. There is evidence for a skewed sex ratio that results in a surplus of unmated males.
American redstarts display a mixed mating strategy; they are predominantly monogamous but around 25% of males maintain multiple territories and arepolygynous. Even within monogamous pairs, a high proportion of offspring—as many as 40%—are not fathered by the male of the pair. The intensity of the male’s coloration (which is due to carotenoid pigments) predicts their success at holding territory in their non-breeding, winter locations in the Caribbean, the probability that they will be polygynous, and the proportion of offspring in their nests that they will themselves father. Males are invariably very territorial and the superior males occupy the best habitats, such as moist mangroves, while inferior males occupy secondary habitats such as dry scrub forests.
The redstarts feed almost exclusive on insects which are usually caught by flycatching. American redstarts also have been known to catch their insect prey bygleaning it from leaves. This is a very active species. The tail is often held partly fanned out. These birds have been observed flashing the orange and yellow of their tails, on and off, to startle and chase insects from the underbrush. Overall, this species is a very flexible, opportunistic feeder that can easily adapt to varying habitat, season, insect community, vegetation structure, and time of day. The diet consists largely of caterpillars, moths, flies, leafhoppers and planthoppers, smallwasps, beetles, aphids, stoneflies and spiders. Few berries and seeds are consumed, but are most often from barberry, serviceberry, and magnolia.
The oldest known redstart to be banded was over 10 years of age. Other adults have been known to live up to around 5 years of age. However, few survive past the first stages of life. Setophaga ruticilla is vulnerable to both terrestrial and aerial predators. Highest rates of predation occur during the breeding season when eggs and helpless nestlings are abundant and easy prey for varied predators. Females mostly brood during this period and thus often fall prey to nest predators. Common terrestrial predators include red squirrels, fishers, eastern chipmunks, American black bears, flying squirrels, fox snakes, and domestic cats. Aerial predators take nestlings, eggs, or even adults in flight. Possible aerial predators include jaegers, blue jays, common ravens, northern saw-whet owls, common grackles, northern goshawks, and sharp-shinned hawks, and Cooper’s hawks.
Successful conservation efforts of the redstart, like any other migrating bird, include protecting and providing habitat throughout its entire range. The benefits to coffee farms that redstarts and other «coffee birds» provide have encouraged coffee farmers to adapt shade trees and adjacent forest patches in their farming practices as additional habitat for the birds. While shade tree coffee farms offer a somewhat practical compromise between habitat preservation and agriculture, there is still not enough data to back the notion that practices like shade tree coffee farms can replace the natural habitat that was once there. Still, the most effective method for American redstart conservation would be natural habitat preservation at wintering and breeding grounds.