Ash-browed Spinetail Cranioleuca curtata


Justification of Red List Category

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Population justification
The global population size has not been quantified. The species is described as uncommon to fairly common, but possibly overlooked (Stotz et al. 1996, Remsen and Sharpe 2020).

Trend justification
This species is suspected to decline as forests within the range are lost and fragmented.
The rate of population decline has not been quantified directly, but tree cover within the range is lost at a rate of 3% over ten years (Global Forest Watch 2021, using Hansen et al. [2013] data and methods disclosed therein). As the species is highly dependent on forests, the population may decline faster than the rate of tree cover loss suggests due to the impact of habitat degradation. However, based on the overall low rate of tree cover loss, it is considered unlikely that the rate of population decline exceeds 10% over ten years.

Distribution and population

Cranioleuca curtata is a polytypic species found in the east Andes of western South America. The nominate subspecies curtata is endemic to central Colombia, from Norte de Santander south as far as Huila. Subspecies cisandina occurs south from west Caquetá, south Colombia, through east Ecuador to north Peru, where it spreads south as far as Pasco and Junín. Subspecies debilis ranges from Ayacucho and Cuzco in central Peru, south to west Santa Cruz in central Bolivia (del Hoyo et al. 2003).


This is a species of montane and lower montane humid and evergreen forest. It shows some tolerance of secondary habitats and is common along edges and in forest remnants (M. Sánchez-Nivicela in litt. 2022). It usually ranges from 900-1,700 m, but may locally be found down to 650 m and up to 2,500 m. It feeds on arthropods. The only breeding information is a record of a fledgling from March in north Ecuador (del Hoyo et al. 2003, Remsen and Sharpe 2020).


The primary threat to this species is accelerating deforestation as forests within the range are converted for ranching and farming (Soares-Filho et al. 2006, Bird et al. 2011).

Conservation actions

Conservation Actions Underway
The species is found in a number of protected areas throughout its extensive range, including Serranía de los Yariguíes National Park (Colombia), Podocarpus National Park (Ecuador), Manu Biosphere Reserve (Peru), Madidi and Isiboro-Sécure National Parks (Bolivia), as well as in several private protected areas (Remsen and Sharpe 2020).

Conservation Actions Proposed
Quantify the population size. Monitor the population trend.
Expand the protected area network to effectively protect key sites. Effectively manage protected areas, utilising emerging opportunities to finance protected area management with the joint aims of reducing carbon emissions and maximizing biodiversity conservation. Incentivise conservation on private lands through expanding market pressures for sound land management and preventing forest clearance on lands unsuitable for agriculture (Soares-Filho et al. 2006).


14-15 cm. Smallish, brown ovenbird. Quite dark. Face is a dull brown, with a pale supercilium. Brown forehead, with reddish chestnut crown. The back is a rich brown, but becomes reddish chestnut lower down, the wings and tail also being this colour. Iris is chestnut to brown, upper mandible brown, lower mandible pinkish. Voice Song is a high-pitched, accelerating, deepening and fading series of shrill notes, lasting around two seconds.


Text account compilers
Hermes, C.

Butchart, S., Ekstrom, J., Khwaja, N., Lees, A., Sharpe, C.J., Symes, A. & Sánchez-Nivicela, M.

Recommended citation
BirdLife International (2022) Species factsheet: Cranioleuca curtata. Downloaded from on 16/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from on 16/08/2022.