Data Zone
Justification of Red List category
This species qualifies as Vulnerable because it has a small population, which is confined to several small subpopulations. The population is declining and reportedly becoming scarce throughout the range, but the reasons for the decline are somewhat unclear.
Population justification
This species is poorly known. It appears to be very rare to rare and very local throughout its range. National population estimates include 250-2,499 mature individuals in Ecuador (Freile et al. 2019), 2,500-9,999 mature individuals each in Peru and Bolivia (Ministerio de Medio Ambiente y Agua 2009; SERFOR 2018), and an unknown, but likely very small, number in Argentina. Based on these numbers, the global population is estimated to number 5,250-23,000 mature individuals.
The species is suspected to form several small subpopulations, the largest of which is unlikely to contain more than 1,000 mature individuals, though this requires confirmation.
Trend justification
Trends have not been well documented, but the species appears to be declining for poorly understood reasons (B. Knapton in litt. 2003). It has been hypothesised that the species is suffering from habitat degradation and loss through the clearance of nesting habitat for sheep grazing and that it is hunted (Farnsworth et al. 2020). The species has reportedly declined in recent decades, being scarce in areas even in areas where it was formerly described as relatively numerous (e.g. Ridgely and Tudor 1994; Farnsworth et al. 2020). In Ecuador, there has been "an apparently precipitous drop in numbers" (Ridgely and Greenfield 2001). The situation in Peru is similar (Schulenberg et al. 2007). In view of the available evidence the species is inferred to undergo an continuing decline, the rate of which is tentatively placed in the band 1-9% over three generations (11.1 years).
Agriornis albicauda occurs in the high Andes from Ecuador through Peru and Bolivia to northern Chile and Argentina.
The subspecies andicola occurs in Ecuador (Imbabura, Pichincha, Napo, Chimborazo, Cañar, Zamora-Chinchipe, El Oro and Loja provinces). The nominate subspecies albicauda occurs in Peru (Cajamarca, La Libertad, Huánuco, Ancash, Pasco, Cuzco, Lima, Arequipa and Ayacucho), Bolivia (La Paz, Oruro, Potosí, Chusquisaca and Cochabamba); north Chile in (Tarapacá, Antofagasta and Arica), and north-west Argentina (Sierra de Aconquija and Tucumán, with one record from Catamarca in 1918).
The species inhabits páramo and puna zones, high above the treeline at 3,500-4,300 m. However, in south Ecuador, it has been found in semi-arid, bushy country, especially in areas with large Puyas, at 2,400-3,100 m (Krabbe et al. 1996). It favours open areas with sparse vegetation and scattered rocks, particularly near old buildings and walls, and has been recorded from rocky Polylepis groves (Ridgely and Tudor 1994; Vuilleumier 1994). There are also records from open farmland with hedgerows and introduced Eucalyptus trees, from agricultural land (crops and pasture) with introduced pine trees, and from cactus scrub with Eucalyptus (Krabbe et al. 1996, N. Simpson in litt. 2000; B. Knapton in litt. 2003; M. Ugarte-Lewis in litt. 2005).
The reasons for the species's scarcity and decline are not fully understood. A potential driver of the decline could be a high sensitivity to habitat degradation, as bushy vegetation is cleared for grazing (Farnsworth et al. 2020). Throughout the range, grasslands have been modified for centuries through burning and grazing (Fjeldså and Kessler 1996; Kessler and Herzog 1998; T. S. Schulenberg in litt. 1999). The species may furthermore suffer from hunting and direct persecution (Farnsworth et al. 2020). Historically, it may have been out-competed by A. montana, and this may continue, although the two have coexisted for at least a million years (T. S. Schulenberg in litt. 1999; B. Knapton in litt. 2003). It is however unclear whether these threats explain the species's rarity.
Conservation Actions Underway
There are recent records from Huascarán National Park, Peru, and Lauca National Park, Chile.
25 cm. Large, greyish-brown tyrant. Dark greyish-brown above, darker on wings. Inconspicuous pale supercilium. White throat heavily streaked blackish. Pale grey-brown breast and flanks. Pale centre to belly. White tail except for dark greyish-brown central rectrices. Heavy, dark bill. Similar spp. Black-billed Shrike-tyrant A. montana is slightly smaller, with less conspicuous streaking on throat, and much thinner and less stout bill.
Text account compilers
Hermes, C.
Contributors
Benstead, P., Capper, D., Fjeldså, J., Geale, D., Harding, M., Khwaja, N., Knapton, B., Krabbe, N., Mazar Barnett, J., O'Brien, A., Povedano, H., Schulenberg, T., Sharpe, C.J., Simpson, N., Symes, A., Temple, H. & Ugarte-Lewis, M.
Recommended citation
BirdLife International (2024) Species factsheet: White-tailed Shrike-tyrant Agriornis albicauda. Downloaded from
https://datazone.birdlife.org/species/factsheet/white-tailed-shrike-tyrant-agriornis-albicauda on 23/12/2024.
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 23/12/2024.