Strange-tailed Tyrant Alectrurus risora Scientific name definitions

The tail of the Strange-tailed Tyrant is strange indeed, at least in the male. The outer pair of rectrices are greatly elongated (they are longer than the bird's body); the bases of the outer pair of rectrices are bare, but the outer two-thirds of the feather are very broad, forming a long streamer. The plumage is black and white, but the breeding male has exposed pinkish or orangey skin on the throat. The behavior of the Strange-tailed Tyrant is no less unusual. This species is polygynous, as males maintain territories where up to four females breed. Currently the Strange-tailed Tyrant largely is restricted to southern Paraguay, northeastern Argentina, and western Uruguay, where it occupies tall grasslands, but the distribution formerly extended much farther north and east. In view of this range contraction, primarily due to habitat loss, the Red List conservation status of the Strange-tailed Tyrant is rated as Vulnerable.

S Paraguay (S from Presidente Hayes) and NE Argentina (E Formosa and Corrientes, rarely Chaco and Misiones; formerly S to Buenos Aires); no recent records from S Brazil and Uruguay.

Eggs in Sept–Dec. Nest an open grassy cup, lined with feathers, hidden on or near ground; in Formosa, Argentina, built in tall grasses such as Imperata brasiliensis, c. 30 cm above ground (1 Di Giacomo, A.S., Di Giacomo, A.G. and Reboreda, J.C. (2011). Male and female reproductive success in a threatened polygynous species: the Strange-tailed Tyrant Alectrurus risora. Condor. 113(3): 619–628. Close ). Clutch three immaculate white eggs, size c 21∙8 mm × 16∙8 mm; incubation period, 16–18 days; chick mass at hatching c. 2∙8 g; recently hatched chicks have orange skin with dense and long down on the head, back and underparts, the mouth being orange with yellow flanges; nestling period 12–14 days (1 Di Giacomo, A.S., Di Giacomo, A.G. and Reboreda, J.C. (2011). Male and female reproductive success in a threatened polygynous species: the Strange-tailed Tyrant Alectrurus risora. Condor. 113(3): 619–628. Close ). Only females build the nest, incubate the eggs, and brood and feed the chicks. In a study in Formosa, more than 80% of males were polygynous and defended contiguous territories of 2–2.5 ha, that included the territories of up to 4 females; successful nests fledged 2·3 chicks on average; nest survival 23%, decreasing with nest age and time of breeding, and 75% of nest failures were due to predation; most females made 2–3 nesting attempts per breeding season (2·3 on average, n = 35) and bred in the same area for 2–3 consecutive years, while males were rarely seen in the same area more than one year, suggesting sexual differences in mortality as well as broadly similar reproductive success of males and females (1 Di Giacomo, A.S., Di Giacomo, A.G. and Reboreda, J.C. (2011). Male and female reproductive success in a threatened polygynous species: the Strange-tailed Tyrant Alectrurus risora. Condor. 113(3): 619–628. Close ).

VULNERABLE. Rare to locally uncommon or fairly common. Estimated global population at least 10,000 individuals continuing to decline, and no recent reports from a large portion of its former range of c. 100,000 km², which is increasingly fragmented owing to native moist grassland being burned, drained and cultivated for pasture, eucalypt (Eucalyptus) and pine (Pinus) plantations and agriculture (encouraged by government incentives). This species’ preference for tall grasses suggests that it is intolerant of even biannual burning (although in years when accidental fires do not affect the whole area, birds nest in the remaining unburned patches and both the number of nesting attempts and the nesting success are similar to years without fire (2 Di Giacomo, A.G., Di Giacomo, A.S. and Reboreda, J.C. (2011). Effects of grassland burning on reproductive success of globally threatened Strange-tailed Tyrants Alectrurus risora. Bird Conservation International. 21: 411–422. Close ) ); pesticides, fertilizers and other chemicals are widely used and must have profound effects. Consequently, there has been a catastrophic loss of range in Brazil (last record in Rio de Janeiro in 1974, and even older records from Mato Grosso, São Paulo and Rio Grande do Sul), Uruguay (formerly uncommon breeder, but only one unconfirmed record since 1986) and Argentina (no recent records from several provinces or from Urugua-í Provincial Park, in Misiones, where all suitable habitat now destroyed). In Paraguay, it remains locally numerous, e.g. W of San Juan Bautista (Misiones), in Estancia San José and La Golondrina Private Nature Reserve (both in Presidente Hayes), and in three areas within San Rafael National Park; also recorded in the proposed Tacuara National Park. In Argentina, regularly recorded at El Bagual, Guaycolec and San Juan de Poriahú Private Reserves, and El Palmar and Mburucuyá National Parks, and in the 12,000-km² Iberá Natural Reserve, in Corrientes, where the largest known population was estimated at c. 23,000 birds in 1992; recent records indicate that numbers in Chaco and Formosa are considerably lower. A conservation award was recently given to study different management regimes and to raise public awareness at Mburucuyá National Park. Although the species is apparently resident throughout much of its range, seasonal movements have been noted in Buenos Aires and several of the Paraguayan records are thought to refer to migrants, making part of the population vulnerable to loss of either breeding or wintering habitats.