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

Justification of Red List category
Napothera pasquieri is one of South-East Asia's most poorly known, and perhaps most threatened, endemic passerines. It is confined to the Hoang Lien Mountains in West Tonkin, northern Viet Nam, where it is known from only a handful of sites. This species is believed to be declining, perhaps rapidly, in response to the proliferation of cardamom plantations in this part of Viet Nam since the 2000s. In particular, the planting of cardamom involves the removal of the dense understorey on which this species depends. Given how few sites this species' sensitivity to habitat degradation and its very limited native range, it is believed to be at high risk of extinction. It is accordingly listed as Endangered.

Population justification
Population size very poorly known and in urgent need of elucidation, but crudely suspected to fall in the band of 500-5,000 mature individuals given the scarcity of records, and the presumed small area of suitable habitat even within its mapped range.

Trend justification
There are no data on population trends for this species but it is evidently declining, potentially rapidly, in response to habitat loss and degradation driven largely by the cultivation of cardamom. North-west Viet Nam has undergone rapid changes over the past two decades and this species' close relationship with certain bamboo species (Arundinaria dwarf bamboo especially: see Eames and Mahood 2011) has rendered it especially susceptible to habitat degradation and the removal of forest understorey. Much of this habitat loss is not adequately captured by remote sensing data, hence while Global Forest Watch (2023) data show only minimal losses from its elevational range (c. 1,200-2,200 m), forest throughout is heavily degraded (Grantham et al. 2020) and reportedly nothing below c. 1,800 m is now suitable (J. Eaton in litt. 2023). Notably, some sites where the species was found in 2020 were vacant (with no suitable habitat) in 2023 (J. Eaton in litt. 2023). This destruction has occurred even in protected areas, with Eames and Mahood (2011) noting more than a decade ago that it was 'almost impossible to find undisturbed evergreen forest undergrowth in Hoang Lien Son and Van Ban Nature Reserves'. Determining potential rates of decline are hampered further by this species' very low occupancy within its already limited range. Consequently the percentage of habitat altered/removed (itself almost indeterminable) is not necessarily parallel to population reduction. Accordingly no rate of population decline is estimated here, but this should be among the highest research priorities for this species.

Napothera pasquieri has a very limited range, being restricted to the Hoang Lien Mountains in West Tonkin, northern Viet Nam, where only a handful of sites are known (Eames and Mahood 2011, eBird 2023). Given the distribution of forest in its elevational range, it is possible that this species awaits discovery in south-easternmost Yunnan, China, but this requires confirmation.

It inhabits submontane and montane forest habitats, including broadleaf evergreen forest, secondary growth and bamboo stands, at c.1,220-2,500 m (Eames and Mahood 2011). It appears to strongly favour areas of forest with an undergrowth dominated by dwarf bamboo of the genus Arundinaria (Eames and Mahood 2011). Nothing is known of the species' diet, but it has been observed to skulk on the forest floor and in undergrowth, where it rummages amongst fallen leaves (del Hoyo et al. 2007, Eames and Mahood 2011).

There are no data on population trends for this species but it is evidently declining, potentially rapidly, in response to habitat loss and degradation driven largely by the cultivation of cardamom. Cardamom cultivation has increased markedly in north-western Vietnam since c.2006 (J. Pilgrim in litt. 2011) and is the most important threat to the species (Eames and Mahood 2011). Cardamom cultivation involves the removal of natural undergrowth (dense Arundinaria sp. bamboo) from intact forest and is equally prevalent within and outside protected areas, with the apparent support or tacit acceptance of authorities (Eames and Mahood 2011, J. Pilgrim in litt. 2011). The resulting understorey of cardamom is much simpler in structure than bamboo and is thought to be unsuitable for the species. All recent records have been from locations with a dense understory of Arundinaria sp. bamboo and surveys have thus far failed to find it in cardamom plots. Cardamom cultivation is so widespread that it is reportedly now almost impossible to find undisturbed evergreen forest undergrowth in Hoang Lien Son and Van Ban Nature Reserves (Eames and Mahood 2011, J. Pilgrim in litt. 2011). This expansion has continued into the 2020s, with some sites the species occupied as recently as 2020 cleared of understorey in 2023 (J. Eaton in litt. 2023). In part, this expansion has been facilitated by the construction of new roads and settlements, rendering almost all forest areas accessible.

Conservation Actions Underway
It occurs in Hoang Lien Son Nature Reserve, Mu Cang Chai Species and Habitat Conservation Area and Van Ban Nature Reserve, which evidently provide very limited protection (Eames and Mahood 2011, J. Pilgrim in litt. 2011). No targeted actions are known.

Conservation Actions Proposed
Determine the true extent of its range, including in southern Yunnan, China. Survey areas of suitable habitat, preferably those furthest from settlements, to improve knowledge of its distribution, and occupancy rates within its range. Ensure that additional parts of this species' range are encompassed by protected areas. Ensure that existing protected areas are effective in preventing habitat degradation (i.e. enforcing that understorey is kept free from cardamom planting). Determine this species' habitat tolerances (particularly its ability to persist in secondary forest types if an understorey remains). Monitor rates of habitat loss and degradation within its range.

11-12 cm. Small, almost tailless, streaky brown babbler, with a very long, slightly decurved bill and prominent white throat. Its crown, nape and head side are darkish rufescent brown with vague buff streaks. Dorsal feathering long, darkish brown and with long buff streaks, becoming vague on dark rufescent rump. Upperwing and tail plain darkish rufescent-brown, face slightly paler, with dark brown submoustachial streak bordering pure white on chin and throat, with clear-cut break to darkish ochre-tinged brown underparts marked with long whitish-buff streaks.

Text account compilers
Berryman, A.

Contributors
Pilgrim, J., Mahood, S., Hung, L. & Eaton, J.

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Recommended citation
BirdLife International (2024) Species factsheet: White-throated Wren-babbler Napothera pasquieri. Downloaded from https://datazone.birdlife.org/species/factsheet/white-throated-wren-babbler-napothera-pasquieri on 21/12/2024.
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 21/12/2024.