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 'fairly common' (Stotz et al. 1996).
Trend justification
There are no data on the population trend, but despite the species' tolerance of some disturbance and secondary and shrubby growth, declines are suspected on the basis of widespread habitat loss.
Within the range, up to 7% of tree cover is lost over three generations (10.7 years; Global Forest Watch 2022, using Hansen et al. [2013] data and methods disclosed therein). Under the assumption that population declines are roughly proportionate to the rate of tree cover loss, they are here placed in the band 1-19% over three generations. The rate of decline may however vary geographically, with steeper declines suspected in areas of extensive logging (e.g. in the eastern part of the range; Global Forest Watch 2022).
Thamnophilus nigrocinereus is a polymorphic species of north-eastern South America.
Subspecies cinereoniger occurs on the drainages of río Meta, in north-east Colombia, the upper Orinoco River, in south-west Venezuela, and the lower Rio Uaupés and Rio Negro, in north-west Amazonian Brazil. Subspecies tschudii is found along the lower Rio Madeira in eastern Amazonas, west-central Brazil, and subspecies huberi occurs along the lower Rio Tapajós in western Pará, east-central Brazil. The nominate subspecies nigrocinereus occurs in east Brazil, ranging along the Amazon River and its tributaries from the mouth of Rio Tapajós eastwards to Amapá. Subspecies kulczynskii is found in coastal mangroves of east French Guiana (del Hoyo et al. 2003).
This is an understorey and middle storey species of flooded forest, gallery forest, dry woodland and sometimes shrubby forest borders (del Hoyo et al. 2003, Zimmer and Isler 2020).
Habitat requirements vary geographically, as different subspecies occupy different habitat types: Throughout most of the Amazon basin, subspecies tschudii and huberi are found on river islands, tall thickets near rivers, as well as along the borders of seasonally flooded 'várzea' and 'igapó' forest and of clearings (Zimmer and Isler 2020). Subspecies nigrocinereus in the eastern Amazon occurs in dense forests surrounded by seasonally flooded grassland, while subspecies cinereoniger in Colombia and Venezuela occurs in dense, seasonally flooded savanna woodland and gallery forest (Zimmer and Isler 2020). Subspecies kulczynskii in French Guiana is solely found in coastal and estuarine mangroves (O. Claessens and V. Pelletier in litt. 2020).
The primary threat to this species is accelerating deforestation in its range for agricultural purposes, livestock ranching and selective logging (Soares-Filho et al. 2006, Bird et al. 2011, ICMBio 2018). It is thought likely to be particularly susceptible to fragmentation and edge effects (A. Lees in litt. 2011). In parts of the range, the construction of hydroelectric dams may affect flow regimes of major rives within the range and thus further contribute to habitat loss and degradation (ICMBio 2018, Aleixo et al. 2021).
Conservation Actions Underway
The species is listed as Near Threatened at the national level in French Guiana (UICN France et al. 2017). While the species is assessed as Least Concern in Brazil, subspecies huberi is separately listed as Vulnerable and subspecies tschudii as Endangered (ICMBio 2018).
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, dimorphic antshrike. Male is blackish grey, with a pale belly and some white on the wings. Female has a blackish cap but is otherwise brown, paler below than above.
Text account compilers
Hermes, C.
Contributors
Butchart, S., Claessens, O., Ekstrom, J., Khwaja, N., Lees, A., Pelletier, V., Phalan, B. & Symes, A.
Recommended citation
BirdLife International (2024) Species factsheet: Blackish-grey Antshrike Thamnophilus nigrocinereus. Downloaded from
https://datazone.birdlife.org/species/factsheet/blackish-grey-antshrike-thamnophilus-nigrocinereus 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.