Castelnau's Antshrike Thamnophilus cryptoleucus


Justification of Red List category

Based on a model of future deforestation in the Amazon basin, it is suspected that the population of this species will decline by 25-30% over the next three generations, and it has therefore been uplisted to Near Threatened.

Population justification
The global population size has not been quantified, but this species is described as 'fairly common' (Stotz et al. (1996).

Trend justification
This species is suspected to lose 15.9-16% of suitable habitat within its distribution over three generations (15 years) based on a model of Amazonian deforestation (Soares-Filho et al. 2006, Bird et al. 2011). Given the susceptibility of the species to fragmentation and/or edge effects, it is therefore suspected to decline by a rate approaching 30% over three generations.

Distribution and population

Thamnophilus cryptoleucus is fairly common along the rivers of lowland Amazonia. In north-east Ecuador and north Peru, it is found locally on río Napo, río Marañon, río Santiago and río Ucayali. From there its range continues east along the Amazon River in west Brazil, as far as the mouth of Rio Negro (del Hoyo et al. 2003).


This is an understorey and middle storey species of várzea (seasonally flooded forest), and the tall growth on islands in white-water rivers. It is also known from the edges of older forest (del Hoyo et al. 2003).


The primary threat to this species is accelerating deforestation in the Amazon basin as land is cleared for cattle ranching and soy production, facilitated by expansion of the road network (Soares-Filho et al. 2006, Bird et al. 2011). It is rendered particularly susceptible because of its reliance on islands: changes in flooding patterns caused by deforestation, or changes in the flow regime driven by river dams, could have serious effects on the species (del Hoyo et al. 2003). It also thought to be generally vulnerable to fragmentation (A. Lees in litt. 2011). Proposed changes to the Brazilian Forest Code reduce the percentage of land a private landowner is legally required to maintain as forest (including, critically, a reduction in the width of forest buffers alongside perennial steams) and include an amnesty for landowners who deforested before July 2008 (who would subsequently be absolved of the need to reforest illegally cleared land) (Bird et al. 2011).


Conservation actions

Conservation Actions Underway
None is known.

Conservation Actions Proposed

Expand the protected area network to effectively protect IBAs. Effectively resource and manage existing and new protected areas, utilising emerging opportunities to finance protected area management with the joint aims of reducing carbon emissions and maximizing biodiversity conservation. Conservation on private lands, through expanding market pressures for sound land management and preventing forest clearance on lands unsuitable for agriculture, is also essential (Soares-Filho et al. 2006). Campaign against proposed changes to the Brazilian Forest Code that would lead to a decrease in the width of the areas of riverine forest protected as Permanent Preservation Areas (APPs), which function as vital corridors in fragmented landscapes.


16-17 cm. Medium-sized, black antshrike. Uniform black with red iris and white patch on shoulder. Male has white on some wing feathers.


Text account compilers
Butchart, S., Ekstrom, J., Khwaja, N., Symes, A.

Lees, A.

Recommended citation
BirdLife International (2023) Species factsheet: Thamnophilus cryptoleucus. Downloaded from http://datazone.birdlife.org/species/factsheet/castelnaus-antshrike-thamnophilus-cryptoleucus on 04/12/2023.
Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 04/12/2023.