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). The population size may be moderately small to large, 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). 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). For these reasons the species is evaluated as Least Concern.
No survey data is available. The species has been described as infrequent and difficult to see (R. Amorin in litt. 2020). Based on the recorded population density of a congener (Phylloscartes virescens: 1.14 individuals per km2; Thiollay 1986), the area of tree cover with over 30% canopy cover within the range in 2010 (94,000 km2; Global Forest Watch 2020) and assuming that only 40-60% of forest within the species's range is occupied, the population size is tentatively suspected to be in the range of 42,864-64,296 individuals, roughly equating to 28,576-42,864 mature individuals. The population size is here placed in the band 20,000-49,999 mature individuals. The species has a disjunct distribution, so is likely to have more than one subpopulation.
Approximately 4% of tree cover was lost between 2009 and 2019 within the species's range (Global Forest Watch 2020). A continuing decline in population size is inferred. The population size is suspected to have declined by 1-9% over the past ten years.
Over three years from 2017-2019, approximately 1.6% of tree cover within the species's range was lost over three years (Global Forest Watch 2020). If this rate were to continue across ten years, this would equate to a loss of 5% of tree cover. Hence, over the next ten years, the population size is suspected to undergo a reduction of 1-9%.
Phylloscartes difficilis occurs in south-east Brazil (Espírito Santo and south Minas Gerais to north-east Rio Grande do Sul). It has a disjunct distribution and is found in the mountains of the Serra da Mantiqueira in the southeast of Minas Gerais, east of Rio de Janeiro, northeast of São Paulo and southwest of Espírito Santo; in the Serra do Mar in the east of Paraná and northeast of Santa Catarina and in the Serra Geral in the southeast of Santa Catarina and northeast of Rio Grande do Sul (WikiAves 2018).
It is resident in the lower growth of montane evergreen forest and edge (Ridgely and Tudor 1994, Parker et al. 1996).
Its montane forests have suffered less destruction than adjacent lowland areas, but the isolated patches in the north of its range have virtually disappeared owing to the expansion of pasture and cultivation. Unregulated tourism increases the risk of fires within the species's range and may lead to habitat clearance due to the development of infrastructure (R. Amorin in litt. 2020).
Conservation Actions Underway
It occurs in Itatiaia National Park, Pico Paraná State Park and Marumbi State Park.
Text account compilers
Amorin, R., Capper, D., O'Brien, A., Sharpe, C.J. & Symes, A.
BirdLife International (2021) Species factsheet: Phylloscartes difficilis. Downloaded from http://www.birdlife.org on 23/04/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/04/2021.