Data Zone
Justification of Red List category
This species is classified as Vulnerable because it has suffered a large contraction in range and, presumably, numbers. Further declines are expected because suitable habitat is subject to extensive agricultural modification and afforestation.
Population justification
The population is estimated to number 10,000-19,999 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size (the lower limit of such estimates for tyrannids is one individual/km2), and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate equates to 6,667-13,333 mature individuals, rounded to 6,000-15,000 mature individuals here.
Trend justification
This species's population is suspected to be declining rapidly, in line with rates of habitat loss within its range.
Alectrurus risora now occurs primarily in south Paraguay (Presidente Hayes, Amambay, Central, Cordillera, Alto Paraná, Paraguarí, Guairá, Misiones, Itapúa and San Pedro) and north Argentina (Di Giacomo and Di Giacomo 2004) (Corrientes, eastern Formosa, and rarely in Chaco and Misiones). There has perhaps been a catastrophic loss of range in Brazil, the last record coming from Rio de Janeiro in 1974 (Pearman and Abadie 1995), with older records from Mato Grosso, São Paulo and Rio Grande do Sul; Uruguay, where it was formerly an uncommon breeder, but has only yielded one unconfirmed record since 1986 (A. B. Azpiroz in litt. 1999), and Argentina (Santiago del Estero, Santa Fe, Entre Ríos, Córdoba, San Luis and Buenos Aires). In 1993, the population in Corrientes was estimated at c.23,000 birds, but recent records indicate that numbers in Chaco and Formosa are considerably lower (di Giacomo and di Giacomo 2004). The species is currently found in only 10% of its historical range in Argentina (Codesido and Fraga 2009, Azpiroz et al. 2012).
It inhabits wet grasslands near or within marshes. It apparently requires relatively tall grasses, mostly over 1-1.5 m (Pacheco and Gonzaga 1994, Di Giacomo and Di Giacomo 2004). Breeding occurs in the austral spring. It feeds on invertebrates. It was formerly partially migratory in north-east Argentina with birds reaching Buenos Aires province in the breeding season and Brazil during the winter, but remnant populations are resident (Di Giacomo and Di Giacomo 2004). In Paraguay it is sedentary, remaining even when grassland has been recently burned (H. del Castillo in litt. 2007). It has been observed following army ants Labidus praedator and armadillos Euphractus sexcinctus to forage for insects (Di Giacomo and Di Giacomo 2006). The mating system is complex (lek-like), involving breeding groups with monogamous and polygamous males that can be maintained for more than 10 years (A. S. Di Giacomo and A. G. Di Giacomo in litt. 2007). It is gregarious, commonly being found in groups of 20 and exceptionally up to 50 birds (H. del Castillo in litt. 2007).
Agricultural conversion and over cattle-grazing of natural grasslands are the principal threats to remaining populations in Argentina (Di Giacomo and Krapovickas 2002, Clay et al. in prep.). Early declines in the Pampas of Argentina were caused by the spread of corn, wheat and soybean monocultures (Di Giacomo and Di Giacomo 2004). Later declines in the central Chaco of Argentina were caused by the establishment of cotton crops (Di Giacomo and Di Giacomo 2004). In Corrientes and Formosa, cattle ranching has not caused critical modifications of natural grasslands. However, spring and summer fires for improving pastures affects reproductive success in Corrientes (A. S. Di Giacomo and A. G. Di Giacomo in litt. 2007). Other short-term threats come from the spread of soybean and rice crops, and pine and Eucalyptus plantations in some traditional cattle ranching areas (Di Giacomo and Di Giacomo 2004). In Corrientes, afforestation with Eucalyptus and Pinus spp., encouraged by government incentives (Di Giacomo and Krapovickas 2002, Clay et al. in prep.), is even affecting wet valley bottoms since trees are often planted adjacent to, or within, inundated grasslands, regardless of their subsequent poor growth and unsuitability for the market (R. Davies verbally 1998). In Paraguay the main threats are loss of grassland habitats for afforestation with Eucalyptus, cattle ranching and the introduction of invasive grasses, and excessive burning. Conversion of wetlands and grasslands for rice fields is a rapidly increasing threat in Eastern Paraguay (H. del Castillo in litt. 2007). Its preference for tall grasses makes it intolerant of even biannual burning (Di Giacomo et al. 2011). Pesticides, fertilisers and other chemicals are widely used and must have profound effects on suitable grasslands (Clay et al. in prep.). It is apparently not disturbed by extensive cattle ranching (H. del Castillo in litt. 2007).
Conservation Actions Underway
CMS Appendix I. It is legally protected in Brazil, Paraguay and Uruguay. The most important and continuous population occurs in Argentina at Reserva Natural del Ibera, Corrientes, a provincial reserve that is established on state and private lands (Di Giacomo and Di Giacomo 2004). It is also protected at Mburucuyá National Park, Corrientes. In Formosa province it is protected at Pilcomayo National Park, El Bagual Private Reserve (where there is a population of 150 individuals), and Guacolec Private Reserve (Di Giacomo 2005). In Chaco province a small population is protected in El Cachape Private Reserve. Its population ecology and the effects of different management regimes are being studied in Formosa and Corrientes provinces (A. S. Di Giacomo and A. G. Di Giacomo in litt. 2007). In Paraguay it occurs at low numbers in the proposed San Rafael National Park, where is protected in a Guyra Paraguay reserve and occurs in others several unprotected areas (mostly cattle ranches). The Grassland Alliance, a conservation initiative acting in Paraguay, Argentina, Brazil and Uruguay, is working to encourage cattle ranchers to keep natural grasslands in their properties (H. del Castillo in litt. 2012).
Conservation Actions Proposed
Conduct quantitative censuses in Chaco and Formosa. Establish a Biosphere Reserve in the southern grasslands of Paraguay. Remove incentives for planting trees on grasslands. Conduct an educational campaign alongside those aimed at protecting the Atlantic Forest to discourage the planting of Eucalyptus as reforestation. Implement the management plan for the Reserva Natural del Ibera to facilitate sustainable land use on private lands. Secure San Rafael National Park (H. del Castillo in litt. 2007). Search for the species at new sites in suitable habitat. Study cattle ranching management best practices on the critical breeding grounds in Argentina (Esteros de Ibera, Corrientes). A population of about 50 birds had been reduced to 10-20 after the construction of a new paved road in the Arroyos and Esteros IBA, Paraguay; farmers inside the IBA should be encouraged to join the Grassland Alliance (H. del Castillo in litt. 2012).
20 cm (male 30 cm including tail). Striking tyrant-flycatcher. Male has black head, back and breast-band. White lower underparts. Unfeathered throat bright pinky-red when breeding. Outer rectrices black and greatly elongated, tapered at base, but outer two-thirds broad. Female has brown streaked upperparts. Diffuse, pale brown breast-band, white lower underparts. Outer rectrices quite elongated, terminating with narrow brown racquets. Similar spp. Individuals lacking tail-streamers resemble Cock-tailed Tyrant A. tricolor, but only A. risora has complete breast-band. Voice Mostly silent, but some inconspicuous calls recorded.
Text account compilers
Capper, D., Mazar Barnett, J., Pople, R., Sharpe, C J, Symes, A., Williams, R., Khwaja, N.
Contributors
del Castillo, H., Di Giacomo, A., Di Giacomo, A., Davies, R., Azpiroz, A.
Recommended citation
BirdLife International (2024) Species factsheet: Strange-tailed Tyrant Alectrurus risora. Downloaded from
https://datazone.birdlife.org/species/factsheet/strange-tailed-tyrant-alectrurus-risora on 22/11/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/11/2024.