Justification of Red List Category
This species has a very 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.
The global population size has not been quantified. The species is described as uncommon to locally fairly common, but infrequently seen (Krabbe and Schulenberg 2020).
Information on population trends is lacking, but the species is suspected to be declining owing to continuing habitat loss and degradation.
Tree cover within the range is lost at a rate of 6% over three generations (10.5 years; Global Forest Watch 2021, using Hansen et al.  data and methods disclosed therein). The species is restricted to forests, and as such population declines may be aggravated by the degradation of forested habitat. Therefore, the rate of population decline is tentatively placed in the band 1-19% over three generations.
Merulaxis ater occurs in south-east Brazil from Espírito Santo and Minas Gerais through Rio de Janeiro, east São Paulo and east Paraná to east Santa Catarina.
This species is uncommon to locally relatively common in thickets within montane and lowland evergreen forest and mature secondary woodland (Ridgely and Tudor 1994, Parker et al. 1996, Naka 2011). It is found in elevations of 400-1,800 m, but may locally be found down to 100 m, although it is almost entirely montane in Espírito Santo and Rio de Janeiro (Sick 1993, Ridgely and Tudor 1994).
Agricultural conversion and deforestation for mining and plantation production historically threatened lowland forests within the range. Current key threats are agricultural expansion, colonisation, urbanisation, industrialisation and associated road-building (Dinerstein et al. 1995, Fearnside 1996). Although montane forests have suffered less destruction, isolated forest remnants in parts of the range have virtually disappeared due to the expansion of pasture and cultivation. Remaining forest fragments are under pressure from clearance and fires spreading from adjacent cultivated areas (Gonzaga et al. 1995).
Conservation Actions Underway
The species occurs in several protected areas throughout its range, including Serra do Mar, Intervales and Carlos Botelho state parks, as well as Itatiaia National Park (Krabbe and Schulenberg 2020).
Conservation Actions Proposed
Quantify the population size. Research threats to the species. Repeat surveys of known sites to determine population trends.
Ensure that remaining areas of suitable habitat receive adequate protection.
Text account compilers
Butchart, S., Gilroy, J., Sharpe, C.J. & Subirá, R.
BirdLife International (2023) Species factsheet: Merulaxis ater. Downloaded from http://datazone.birdlife.org/species/factsheet/slaty-bristlefront-merulaxis-ater on 07/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 07/06/2023.