EXTINCIÓN, HISTORIA NATURAL Y CONSERVACIÓN DE LAS POBLACIONES DEL YETAPÁ DE COLLAR (ALECTRURUS RISORA) EN LA ARGENTINA

DI GIACOMO, ADRIÁN S.; DI GIACOMO, ALEJANDRO G.

ORNITOLOGIA NEOTROPICAL

Neotropical Ornithology Society

Lugar: Montreal; Año: 2004 vol. 15 p. 1 - 14

1075-4377

Strange-tailed Tyrants (Alectrurus risora) are globally threatened and classified as vulnerable. Their populations inhabited temperate and subtropical grasslands of Argentina, Paraguay, Brazil and Uruguay, but they have declined dramatically and, currently, most of the populations are limited to Argentina and south of Paraguay. On the basis of a literature and museum survey, field trips and direct observations, we present information about the extinction pattern, distribution, natural history and conservation of the species in Argentina. The past range covered 10 provinces, but the current populations are located in eastern Formosa and northeastern Corrientes. Between 1840 and 1991, the extent of the species range decreased from 380 400 to 41 500 km2 in association with major environmental transformations. Also, in the past, the population on northeastern Argentina was partially migratory, reaching Buenos Aires province during the breeding season, and Brazil during the winter. Currently, the remnant populations are all year residents and the area that they occupy could be considered as a “refuge” since it maintains the conditions and resources to develop the whole annual cycle. Breeding occurs between September and January. The nest is located in tall grasses close to the ground, and parental care is carried out by females. Clutch size is three eggs and they are incubated during 16 days. Chicks remain in the nest for 12–15 days. The populations of Strange-tailed Tyrants disappeared from the pampas due to intensive agriculture, and from the Central Chaco due to the spread of invasive species of Prosopis in the savannas, and the establishment of cotton crops. In Corrientes and Formosa, the cattle ranching has not produced critical modifications of natural grasslands, but there are short-term threats from the spread of soybean and rice crops, and pine and eucalyptus plantations. Only three populations of this species are protected in reserves and others are in Important Bird Areas. More information is needed concerning the responses of  the species to the management actions in the remnant natural grasslands.