Justification of Red List Category
This species is classified as Vulnerable because it has a very small range and is known from just two locations. It is therefore highly susceptible to stochastic events, and may be increasingly threatened in the near future by potential human developments in the area.
The population is estimated to number 1,000-2,499 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, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
There is no new information on population size or trends, and no evidence of any currently active threats to the population.
Basileuterus ignotus is confined to a very small range, estimated at c.180 km2, on Alturas de Nique and Cerro Tacarcuna in Darién, Panama, and north-west Chocó, Colombia (Wetmore 1984, Ridgely and Gwynne 1989, Wege 1996). Within this range it is thought to occupy an area of less than 100 km2 of suitable habitat (Wege 1996). It is generally uncommon (Ridgely and Gwynne 1989), but was found to be fairly common above 1,400 m on Alturas de Nique (above Cana) in 1985 (Robbins et al. 1985).
It inhabits the lower growth of humid elfin forest, where it is mainly recorded between 1,350 and 1,650 m, but sometimes as low as 1,200 m (Ridgely and Gwynne 1989). The breeding behaviour is virtually unknown, but recently fledged young have been seen in July (Robbins et al. 1985).
Its small range puts it at inherent risk from any habitat loss or degradation. Habitat in the region is being cleared and degraded for mining, agriculture and cultivation of coca (Wege 1996), but probably not yet within the altitudinal range of this species. Completion of the Pan-American highway link through Darién could lead to severe, long-term damage of forests in Darién and the adjacent Chocó (Alvarez-Cordero et al. 1994, Wege 1996).
Conservation Actions Underway
The Panamanian part (i.e. the majority) of its range lies entirely within Darién National Park (Wege 1996). However, legal protection has not halted habitat loss at lower altitudes (Wege 1996). In Colombia, it may be found to occur within Katíos National Park (Renjifo et al. 2002).
13.5 cm. Distinctively marked warbler. Dull olive-green upperparts, creamy-yellow underparts, greenish-yellow supercilium bordered by black above, rufous crown, dusky olive ear-coverts. Voice Song is undescribed. Call a penetrating tseeut.
Text account compilers
Bird, J., Butchart, S., Gilroy, J., Isherwood, I., Pople, R., Sharpe, C J, Stuart, T.
BirdLife International (2019) Species factsheet: Basileuterus ignotus. Downloaded from http://www.birdlife.org on 21/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/08/2019.