LC
Red-and-black Grosbeak Caryothraustes erythromelas



Justification

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 is very large, and hence does not 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.

Population justification
The global population size has not been estimated directly, but this species is described as 'uncommon and patchily distributed' (Stotz et al. 1996, O. Ottema in litt. 2020), and is not present in all suitable habitat patches within its range (Thiollay 2002). Based on the minimum recorded population density of a congener (Caryothraustes canadensis, 2.1 individuals per km2; Thiollay 1986), the estimated area of forest within the species's range in 2010 (1,090,000 km2; Global Forest Watch 2020), and assuming 10-25% of the forest is occupied by the species, the population size is tentatively suspected to fall within the band 216,200 - 540,800 individuals, roughly equating to 144,100 - 360,500 mature individuals and here placed in the band 100,000 - 499,999 mature individuals.

Trend justification
Remote-sensed data indicates that over ten years from 2009-2019, approximately 7% of tree cover was lost within the species's mapped range (Global Forest Watch 2020). The species is therefore inferred to be undergoing a continuing decline.

An analysis of the impact of disturbance on forest species in Pará found that in private lands or sustainable-use reserves, the impact of disturbance on biodiversity was equivalent to that of an additional 51% loss of forest (Barlow et al. 2016). Assuming that the population size is proportional to forest area, and taking into account the potential additional impact of disturbance, the population size is suspected to have undergone a reduction 7-11% over the past decade.

Over the period 2016-2019, approximately 4% of the total forest area was lost. If this rate were to continue over the next ten years, this would amount to a loss of 10%. Assuming that the population size is proportional to forest area, and that disturbance may increase the impact of deforestation by 51%, a population reduction of 7-15% is suspected over the next decade.

Distribution and population

Extreme eastern Venezuela, northern and central Guyana, Suriname (except southwest), French Guiana and Brazil from Amapá south to Pará and Maranhão (del Hoyo et al. 2011, WikiAves 2015) and west across southern Amazonian Brazil into the Madeira drainage in Rondônia (Fernandes 2007, A. Lees in litt. 2011, WikiAves 2015).

Ecology

The species is found in the lower levels of pristine mature lowland humid forest, terre firme, and seasonally flooded forest. Occasionally it ranges into subcanopy, but does not appear to join mixed-species flocks. It is recorded from sea level to 1,100m (Milensky et al. 2016). It occurs at low density and does not appear to adapt to human habitat modifications, though the species has been recorded in selectively logged forest (A. Lees in litt. 2011).

Threats

Deforestation is the primary threat affecting this species (Soares-Filho et al. 2006, Bird et al. 2011). It requires near pristine forest (del Hoyo et al. 1992) and so is especially sensitive to fragmentation and disturbance, particularly as it is already rare and occurs at low densities. Deforestation has been especially rapid in the Belem area in Pará (Global Forest Watch 2020), due to the expansion of agribusiness, logging and grazing, and the species is likely to be locally extinct in this area (Moura et al. 2014). Remote-sensed data has indicated that the rate of clear cut deforestation in the Brazilian legal Amazon was higher in 2019 than in the previous few years, and was particularly high in the state of Pará (INPE 2019). A study found that disturbance caused by fire and logging significantly added to the biodiversity loss caused by deforestation in Pará (Barlow et al. 2016). In Suriname, possible threats are logging and gold mining, the former of which is increasing rapidly (O. Ottema in litt. 2020). Around 10-20% of primary inland forest in Suriname are timber concessions, and around 20-30% of inland forests are gold mining concessions (GONINI 2020, O. Ottema in litt. 2020). Destroyed areas are often relatively small and are surrounded by rainforest, and more than 50% of forests south of the savannah belt are still pristine (O. Ottema in litt. 2020).

Conservation actions

Conservation Actions Underway
It occurs in a number of protected areas, including the Brownberg Nature Park and the Central Suriname Nature Reserve, both in Suriname (O. Ottema in litt. 2020).

Conservation Actions Proposed
Carry out surveys to estimate the species's population densities. Continue to monitor habitat loss within its range. 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).

Identification

20.5 cm, 48 g (n=1 male). Head, chin and throat black. Male with bright red nape collar and underparts, deep reddish upperparts. Female greenish-yellow, brightest on nape and underparts including vent. Massive dark bill with paler base of the lower mandible. Similar spp. Female may be confused with Yellow-green Grosbeak Caryothraustes canadensis but in that species the black is restricted to the foreface and does not extend on to the crown or ear coverts. Voice Series of exceptionally sweet rising and falling phrases consisting of variations on 2-3 standard phrases; delivered slowly and hesitantly. Call a sharp and high-pitched "spink".

Acknowledgements

Text account compilers
Wheatley, H.

Contributors
Butchart, S., Ekstrom, J., Lees, A. & Ottema, O.


Recommended citation
BirdLife International (2024) Species factsheet: Red-and-black Grosbeak Caryothraustes erythromelas. Downloaded from https://datazone.birdlife.org/species/factsheet/red-and-black-grosbeak-caryothraustes-erythromelas on 24/12/2024.
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 24/12/2024.