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Grey-crowned Crocias Laniellus langbianis



Justification

Justification of Red List Category
This species is known from only three sites and is likely to have a very small, declining range as a result of the destruction and degradation of its montane evergreen forest habitat. It therefore qualifies as Endangered.

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. There is not sufficient evidence available to downlist the species.

Trend justification
Up-to-date information on population status is lacking, but various factors influencing habitats in the region are thought likely to be causing a population decline of 1-19% over ten years. The impact of these factors may increase in the near future with growing human population pressure.

Distribution and population

Laniellus langbianis is endemic to montane central Annam, Vietnam, where it is known from Lam Dong and Dak Lak provinces on the Da Lat Plateau, and has recently been discovered at Mang Den, Kontum province (T. Wheatley in litt. 2016). Previously known from only five specimens collected at two localities in 1938-1939, it was rediscovered in 1994 and subsequently has been found at 7 sites on the Da Lat Plateau (Eames et al. 1995, Mahood and Eames 2012). It appears to be very locally distributed and is considered fairly common only at Chu Yang Sin Nature Reserve and at Mang Den, however development at these sites may already be reducing their suitability (T. Wheatley in litt. 2016). A survey in Lam Dong province in 2009 resulted in the discovery of the species at three previously unknown sites, with two pairs in Da Nhim Watershed Protection Forest, three pairs in D'Ran Watershed Protection Forest and seven pairs in forest compartments of Don Duong Forest Company, which is being logged on a 35-year rotation (Mahood and Eames 2012). Virtually all remaining habitat within the range of the species appears to be at the edge of its elevational tolerance, and it appears highly localised and scarce throughout (Mahood and Eames 2012).

Ecology

It is resident in closed-canopy, tropical montane evergreen forest from 900-1,700 m (most recent observations come from a narrow altitudinal band from 910-1,130 m). Generally encountered in singles, pairs, and occasionally small groups of up to five, it is arboreal and forages with mixed-species flocks for invertebrates, particularly caterpillars, primarily in the outer canopy of broadleaved evergreen and coniferous trees.

Threats

A government resettlement programme has greatly increased human pressure on the Da Lat Plateau, exacerbating problems of forest degradation and fragmentation through logging, shifting agriculture, fuelwood-collection and charcoal production. Frequent use of fire to clear land for cultivation prevents evergreen forest regeneration and promotes unsuitable fire-climax pine-dominated woodland. These activities threaten all known sites for the species. Fieldwork in 2009 identified two new localities for the species which are currently being cleared for a hydroelectric project that started in 2008. Areas of primary evergreen forest within the altitudinal range of the species in the Da Nhim Watershed Protection Forest is also being threatened with forest clearance for coffee and Japanese horseradish plantations (Anon. 2009), which is likely to represent a serious threat to the species. On Mt Lang Bian, all land below 1,500 m is now logged or under cultivation. At Chu Yang Sin, a road has been constructed that virtually reaches the 900 m contour.

Conservation actions

Conservation Actions Underway
It occurs in one protected area, Chu Yang Sin Nature Reserve, which was included in the list of protected areas endorsed by the Government of Vietnam for establishment in 1986. The final boundaries of the reserve have yet to be been agreed and no protection measures exist. However, this site is currently under less pressure from logging and hunting than most other areas on the Da Lat Plateau.

Conservation Actions Proposed
Conduct further surveys in areas likely to support the species and identify those of high importance (BirdLife International 2009). Monitor population size and habitat changes at known sites in order to determine population trends. Gazette an extension to, and initiate management activities in, Chu Yang Sin Nature Reserve. Establish further protected areas containing populations of the species. Minimise further immigration into Lac and Krong Bong districts. Promote sustainable management of charcoal production on Mt Lang Bian and Ho Tuyen Lam and promote ecotourism there.

Identification

22 cm. Slim babbler with slaty-grey crown, blackish mask and boldly blackish-streaked flanks. Dull rufous upperparts with blackish-brown streaks and faint, pale shaft streaks on crown, nape and mask. White rest of underparts. Mostly slaty-grey, white-tipped tail, mostly grey greater coverts and secondaries and white-fringed, blackish primaries. Juvenile has browner crown with broader buffish streaks, duller head-sides, smaller flank-streaks, browner greater coverts and secondaries and narrower, white tail feather tips. Voice Song is loud wip'ip'ip-wiu-wiu-wiu-wiu-wiu-wiu-wiu (usually 7-8 wiu notes). Hints Listen for song in montane forest.

Acknowledgements

Text account compilers
Khwaja, N., Benstead, P., Gilroy, J., Tobias, J., Davidson, P., Martin, R, Derhé, M., Peet, N.

Contributors
Wheatley, T., Mahood, S.


Recommended citation
BirdLife International (2019) Species factsheet: Laniellus langbianis. Downloaded from http://www.birdlife.org on 15/12/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 15/12/2019.