Data Zone
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, but this species is described as uncommon to fairly common (Stotz et al. 1996, Schulenberg and Rosenberg 2020).
Trend justification
There are no data on the population trend, but declines are suspected on the basis of accelerating rates of deforestation along large rivers in the Amazon basin.
Within the range, 5% of tree cover is lost over ten years (Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein). Even though the species appears to show some tolerance of low levels of human disturbance (Schulenberg and Rosenberg 2020), the population may be disproportionately affected as its riverine habitat is easily accessible and thus highly susceptible to forest loss and degradation. Precautionarily, population declines are therefore here placed in the band 1-19% over ten years.
Thamnophilus cryptoleucus occurs along the major rivers of lowland Amazonia. In Ecuador and Peru, it is found locally on ríos Napo, Marañon, Santiago and Ucayali. From there its range continues east along the Amazon River in south Colombia and west Brazil, as far as the mouths of ríos Negro and Madeira.
This is an understorey and middle storey species of "várzea" (seasonally flooded forest), and the tall growth on islands and along the banks of white-water rivers. Even though it prefers forest it may also be found on the edges of older forest, in small clearings and in areas with low levels of human disturbance (del Hoyo et al. 2003, Schulenberg and Rosenberg 2020).
The primary threat to this species is accelerating deforestation in the Amazon basin, as land is cleared for agricultural production (Soares-Filho et al. 2006, Bird et al. 2011). It is rendered particularly susceptible because of its reliance on islands and riparian forest, which are easily accessible and therefore subject to higher levels of human encroachment and logging activities (Schulenberg and Rosenberg 2020, Global Forest Watch 2022). Moreover, changes in flooding patterns and flow regime caused by deforestation, the construction of river dams or global climate change, could have serious effects on the species (del Hoyo et al. 2003).
Conservation Actions Underway
None is known.
Conservation Actions Proposed
Survey to locate additional populations and to identify the true extent of the distribution range. Quantify the population size. Research the species' ecology, behaviour and population structure. Research the impact of threats on the population size. Monitor the population trend. Monitor rates of habitat loss.
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).
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
Hermes, C.
Contributors
Butchart, S., Ekstrom, J., Khwaja, N., Lees, A. & Symes, A.
Recommended citation
BirdLife International (2024) Species factsheet: Castelnau's Antshrike Thamnophilus cryptoleucus. Downloaded from
https://datazone.birdlife.org/species/factsheet/castelnaus-antshrike-thamnophilus-cryptoleucus on 26/12/2024.
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 26/12/2024.