• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Justification of Red List category
The species's population is estimated at less than 10,000 mature individuals. A total dependence on one or few species of bamboo, whose reproduction is followed by massive die-off events, suggests that the species's current population is fluctuating and declining due to the clearing of its bamboo habitat. It consequently qualifies as Vulnerable.

Population justification
The population is estimated to number 2,500-9,999 mature individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 3,750-14,999 individuals, rounded here to 3,500-15,000 individuals.

Trend justification
This species's population is inferred to be declining as habitat within its range is lost.

Biatas nigropectus is rare in south-east Brazil and uncommon in north-east Argentina. All Argentine records are from Misiones, where the largest series of specimens has been obtained. The species persists in stands of Guadua trinii bamboo throughout northern and eastern Misiones from Iguazú National Park to the Yabotí Biosphere Reserve, and especially in the area from the northern half of the Yabotí Biosphere Reserve to Santa Rosa and Piñalito Sur (Bodrati and Cockle 2006, A. Bodrati in litt. 2007). Between 2003 and 2011, more than 300 individuals have been detected in Misiones using tape playback (Bodrati and Cockle 2006, A. Bodrati in litt. 2007, A. Bodrati and K. Cockle in litt. 2012). In Brazil, most records are from Rio de Janeiro and São Paulo, with Itatiaia National Park and Intervales State Park particular strongholds. There are further records from Minas Gerais, from Itatiaia on the border with Rio de Janeiro, and at Itabira and São Domingos do Prata in the mid-1980s; Paraná, from Iguaçu National Park, Fazenda Santa Rita and the Tibagi River Basin (Anjos et al. 1997), and Santa Catarina, from Araranguá (do Rosário 1996) and Serra do Itajaí National Park (Kohler et al. 2009). Evidence from the 19th century indicates that this was always a rare bird, but it is presumably declining in response to habitat loss.

It inhabits stands of bamboo in lowland and montane Atlantic forest up to 1,200 m, occurring primarily in openings and along edges where thickets are most extensive and tall. In Argentina, it is an extreme habitat specialist, found only in stands of Guadua bamboo, with nearly all records in Guadua trinii (Bodrati and Cockle 2006, A. Bodrati in litt. 2007). In Argentina, it inhabits stands of Guadua trinii bamboo even on small-holder farms where all other forest vegetation has been removed (A. Bodrati in litt. 2007). The diet includes insect larvae, spiders, small ants and seeds (Bodrati et al. 2005). Breeding is probably between October and January. It is usually very hard to observe, individuals being hidden among foliage in the bamboo canopy and rarely vocalising spontaneously (Bodrati and Cockle 2006, A. Bodrati in litt. 2007).

In Brazil, there has been rapid destruction and fragmentation of Atlantic forest for agriculture, mining, and coffee, banana and rubber plantations (Fearnside 1996). Remaining forest in Brazil suffers from urbanisation, associated road-building and agricultural expansion (Dinerstein et al. 1995). In Argentina, the species depends on Guadua trinii bamboo (Bodrati and Cockle 2006), which has a 30 year cycle of growth, mast seeding, and massive die-off (Parodi 1955). It is not known how Biatas nigropectus responds to these bamboo cycles, but strong population fluctuations are suspected, with bottlenecks during periods of bamboo die-off, increasing the species's vulnerability to stochastic extinction (A. Bodrati in litt. 2007). It is a species that could easily fall through the cracks of current conservation policies, because its bamboo habitat is rarely contemplated in conservation strategies for the Atlantic forest. In Misiones, most Guadua trinii, and hence most records of Biatas nigropectus, are outside of parks, often near houses, plantations and roads, where the bamboo has colonised degraded forest and is at considerable risk of being cleared (A. Bodrati in litt. 2007, A. Bodrati and K. Cockle in litt. 2012).

Conservation Actions Underway
It occurs in a number of protected areas: Itatiaia, Serra dos Órgãos, Serra do Itajaí (Kohler et al. 2009) and Iguaçu national parks, Juréia-Itatins Ecological Station (Develey 1997), Intervales, Serro do Mar and Desengano state parks, all in Brazil, and Yabotí Biosphere Reserve (A. Bodrati in litt. 2007), Iguazú National Park, and Cruce Caballero, Piñalito, and Urugua-í provincial parks, in Argentina (Wege and Long 1995, Bodrati and Cockle 2006). Proyecto Selva de Pino Paraná is raising local awareness of this species and its dependence on Guadua trinii around San Pedro and Tobuna, Misiones. Formerly considered Vulnerable at the national level (Silveira and Straube 2008), it is now considered Near Threatened in Brazil (MMA 2014).

Conservation Actions Proposed
Survey to estimate population densities and clearly delineate the distribution of this species using tape-playback. Study its dependence on Guadua bamboo, particularly in Brazil where other genera are reportedly used (A. Bodrati and K. Cockle in litt. 2012). Determine its response to massive bamboo die-off events, to advise the creation of networks of protected areas capable of sustaining the species through full cycles of bamboo growth and die-off. Determine the minimum size of bamboo stands needed to support a territory. Study the ecology and life cycle of Guadua bamboos. Assess the distribution of its bamboo habitat. Target populations of Biatas nigropectus when creating or enlarging protected areas in Argentina, e.g. Cruce Caballero Provincial Park (Bodrati and Cockle 2006). Protect key areas in Santa Catarina and Paraná. In Misiones, raise local awareness and provide technical support to promote soil conservation on small-holder farms, especially around parks, to avoid clearing of Guadua bamboo for crops. Conservation strategies for the Atlantic forest should include measures to conserve the complex spatio-temporal dynamics of bamboo stands and their inhabitants (A. Bodrati and K. Cockle in litt. 2012).

18 cm. Brown-and-black antshrike. Overall rich brown with rufous wings and tail, olivaceous-buff below. Male has black cap, which is often raised. White ear-coverts and chin join pale buff nuchal collar. Whitish supercilium sometimes hidden. Black lower throat and breast. Considerable variation between individuals in extent of black bib, and colour of bill (ivory to silver) and legs (grey to light blue); individuals with different colouration exist at the same sites and variation does not appear to be geographically based. Female has rufous crown, whitish supercilium and olive-brown breast. Similar spp. Female similar to White-collared Foliage-gleaner Anabazenops fuscus, which lacks rufous crown and wings, and has different bill shape and behaviour. Voice Series of 6-12 soft, fluty kíu notes (c.2 per second).

Text account compilers
Khwaja, N., Pople, R., Capper, D., Hermes, C., Sharpe, C.J., Symes, A., Wheatley, H., Williams, R.

Contributors
De Luca, A., Bodrati, A., Cockle, K.

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Recommended citation
BirdLife International (2024) Species factsheet: White-bearded Antshrike Biatas nigropectus. Downloaded from https://datazone.birdlife.org/species/factsheet/white-bearded-antshrike-biatas-nigropectus on 23/11/2024.
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 23/11/2024.