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 or Area of Occupancy <2,000 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 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). 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 this species is described as 'common' (Stotz et al. 1996) or 'fairly common' (Whittaker 2009). The subpopulation structure is unknown.
Remote sensing data indicates that approximately 6.5% of tree cover with at least 50% canopy cover was lost from the species's range over the past decade to 2020 (Global Forest Watch 2021). Based on the rate of forest loss over the past four years (Global Forest Watch 2021), and assuming deforestation continues at the same pace, it is projected that 8% of the species's habitat may be lost over the next decade. An analysis of the impact of forest degradation in northeast Amazonia found that it contributes, on average, an additional 51% decline in biodiversity (Barlow et al. 2016). This species is dependent on forest and is considered sensitive to disturbance (Zimmer and Isler 2020), so its population size may be declining at a faster rate than that suggested by the rate of tree cover loss. The species's population size is nevertheless suspected to be declining by less than 20% per decade.
This species occurs from the east bank of the Rio Madeira south and east through Rondônia to west Mato Grosso on the Serra dos Parecís and Serra das Ararasin in central Amazonian Brazil.
The species is found at elevations up to 300 m (Ridgely and Tudor 1994), and is common in undergrowth of wet várzea evergreen forest. It is thought to be highly sensitive to disturbance (Zimmer and Isler 2020). It is considered to be an obligate ant-following species, obtaining virtually all of its prey items from attending primarily Eciton burchelli swarms and seizing arthropods that are flushed by the ants. Breeding is thought to take place during the rainy season, with fledging occurring from February onwards.
Deforestation is the primary threat affecting this species (Soares-Filho et al. 2006; Bird et al. 2011). The species is highly sensitive to human disturbance and is suffering from widespread deforestation, particularly in Mato Grosso and Rondônia, which has increased markedly since the 1960s owing to road building, ranching, agriculture, commercial logging, mining and hydroelectric development (Cleary 1991; Ridgely and Tudor 1994; Stotz et al. 1996; M. Cohn-Haft in litt. 1999).
Conservation Actions Underway
A significant proportion of the range of the species now lies within Protected Areas (A. Lees in litt. 2011), including the Pacaás Novos National Park in Rondônia.
Conservation Actions ProposedCarry out surveys to gain an estimate of the population size and trends. Research the species's distribution. Research the impact of forest degradation on the species. Monitor habitat loss and degradation within the species's range.
14-15cm, 28-34g. Large bare periorbital patch, ear coverts, breast sides, breast and throat all white. Top of head black in male, chestnut brown in female. Upperparts olive-brown, female has buff-edged black tips to coverts, mantle, and rest of underparts while the male is plain, and has grey underparts. Similar spp. Bicoloured Antbird Gymnopithys leucapsis has a similar pattern of white throat and breast, and the nominate has white extending onto face sides. This does not extend across the whole of the ear coverts or the breast sides, both of which are black. The periorbital patch is also smaller than in R. hoffmansi. Voice Loudsong begins with a long slurred whistle followed by 6-7 shorter whistles becoming downslurred and ending with a few lower pitched burry notes. Calls are similar to R. gymnops; a harsh "chirr" and an abrupt "chip".
Text account compilers
Fisher, S., Ekstrom, J., Butchart, S., Symes, A., Harding, M. & Mendes Lima, D.
BirdLife International (2023) Species factsheet: Rhegmatorhina hoffmannsi. Downloaded from http://datazone.birdlife.org/species/factsheet/white-breasted-antbird-rhegmatorhina-hoffmannsi on 10/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 10/06/2023.