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Dusky Tetraka Bernieria tenebrosa

Justification
The species appears to have a small range which is severely fragmented and continuing to decline in extent, owing to widespread destruction and degradation of its forest habitat. The total population size is unknown but could be small, given the species's apparently very patchy distribution within its range. At present the species is treated as Vulnerable until improved information on its population and distribution becomes available.

Taxonomic source(s)
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Synonym(s)
Bernieria tenebrosus BirdLife International (2004), Phyllastrephus tenebrosus Collar and Andrew (1988), Phyllastrephus tenebrosus Sibley and Monroe (1990, 1993), Phyllastrephus tenebrosus Collar et al. (1994), Phyllastrephus tenebrosus BirdLife International (2000)

Identification
14-15 cm. Small, rotund, terrestrial babbler-like bird. Dull dark earth-brown upperparts, with no green or yellow. Bright yellow eye-ring and loral streak to eye, and oval patch on throat. Breast similar dark brown to upperparts, belly paler. Legs stout. Bill and tail rather short. Bill mostly pale pink; pinkish-grey legs. Similar spp. From other Malagasy greenbuls by largely terrestrial habits, dark upper- and underparts, short tail, narrower yellow eye-ring and throat patch, and stronger legs. Hints Hops along ground in lowland rainforest, often in rather open areas.

Distribution and population
Bernieria tenebrosa is found only in lowland rainforest in eastern Madagascar, where it is apparently extremely scarce (ZICOMA 1999). The species has been widely misidentified and only recently have the key identification criteria been elucidated (Morris and Hawkins 1998). The only reliable records in recent years have been from Marojejy (800 m), Masoala (200 m) and Zahamena (500 m), but it is probably present in all large blocks of suitable habitat (ZICOMA 1999). If many apparently spurious reports from Ranomafana and Perinet-Analamazaotra are discounted, it has the most restricted range of the eastern Malagasy rainforest species (ZICOMA 1999). Specimens are known from the central-east (Forêt Sihanaka, near Zahamena, and Mantadia [ZICOMA 1999]). During inventories of protected areas at Andringitra, Anjanaharibe-South, Andohahela and Marojejy, the species has been recorded only once and never mist-netted, despite around 10 months of survey effort and substantial mist-netting effort (ZICOMA 1999).

Population justification
The population size is preliminarily estimated to fall into the band 2,500-9,999 individuals. This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification
The species's population is suspected to be declining in line with the clearance and degradation of lowland rainforest in eastern Madagascar. The likely rate of decline, however, has not been estimated.

Ecology
This still-mysterious species is found in the understorey of both lowland and mid-altitude (up to 950 m) undisturbed, humid, evergreen forest. It forages for small insects, larvae and small spiders, both on the ground and in low shrubs (Randriamanindry 1995, Morris and Hawkins 1998). It often occurs with other ground or low-understorey species, and has been observed recently in mixed-species foraging flocks, where there were usually fewer B. tenebrosa than Spectacled Tetraka B. zosterops or Common Tetraka B. madagascariensis (Randriamanindry 1995, Morris and Hawkins 1998).

Threats
Its habitat is being reduced in extent, the principal threat coming from slash-and-burn cultivation by subsistence farmers, which results in progressively more degraded regrowth and leads eventually to bracken-covered areas or grassland (Du Puy and Moat 1996). Much of the eastern coastal plain has either already been cleared or is covered by highly degraded forest (Jenkins 1987), remaining habitat is under pressure from the increasing human population (Jenkins 1987), and commercial logging is an additional threat in some areas (A.F.A. Hawkins in litt. 1995). If present trends continue, the remaining forest will disappear within decades (Du Puy and Moat 1996).

Conservation Actions Underway
This species is known from only three eastern Malagasy IBAs (ZICOMA 1999), including the following protected areas: Marojejy National Park, Masoala National Park, Zahamena National Park (Morris and Hawkins 1998).Conservation Actions Proposed
Locate other populations. Establish habitat requirements and other factors limiting its distribution/population, in order to better predict its likely distribution and population size. Monitor the clearance and degradation of forest within its potential range. Increase the area of suitable habitat that has protected status.

References
Collar, N. J.; Stuart, S. N. 1985. Threatened birds of Africa and related islands: the ICBP/IUCN Red Data Book. International Council for Bird Preservation, and International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.

Du Puy, D. J.; Moat, J. 1996. A refined classification of the primary vegetation of Madagascar based on the underlying geology: using GIS to map its distribution and to assess its conservation status. In: Lourenço, W.R. (ed.), Proceedings of the International Symposium on the biogeography of Madagascar, pp. 205-218. ORSTOM, Paris.

Jenkins, M. D. 1987. Madagascar: an environmental profile. International Union for Conservation of Nature and Natural Resources, Cambridge, U.K.

Morris, P.; Hawkins, F. 1998. Birds of Madagascar: a photographic guide. Pica Press, Robertsbridge, UK.

Randriamanindry, J. J. 1995. The Dusky Greenbul Phyllastrephus tenebrosus in the Zahamena Strict Reserve, Madagascar. Working Group on Birds in the Madagascar Region Newsletter 5: 1.

ZICOMA. 1999. Zones d'Importance pour la Conservation des Oiseaux a Madagascar.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Evans, M., Shutes, S., Starkey, M., Symes, A., Taylor, J.

Contributors
Hawkins, F., Lambert, F., Rabenandrasana, M., Schulenberg, T.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2014) Species factsheet: Bernieria tenebrosa. Downloaded from http://www.birdlife.org on 18/12/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 18/12/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Vulnerable
Family Sylviidae (Old World warblers)
Species name author (Stresemann, 1925)
Population size 1500-7000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 16,000 km2
Country endemic? Yes
Links to further information
- Additional Information on this species