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

Justification of Red List category
This uncommon species is suspected of suffering moderately rapid declines in line with large-scale habitat losses in its range. As an extreme lowland specialist (occurring only rarely above 200 m) it is especially vulnerable, and impacts of habitat loss may be compounded by localised hunting. It is therefore classified as Vulnerable.

Population justification
The global population size has not been quantified, but the species is described as uncommon or rare, although it is common in some areas of swamp forest in southern Borneo and southeast Johor, Peninsula Malaysia (Wells 1999, Gibbs et al. 2001, D. L. Yong in litt. 2016, Eaton et al. 2021).

Trend justification
There are no direct trend data available for this species, but it is inferred to be in rapid decline owing to habitat loss and degradation. Although there are sporadic observations in other habitats (the species appears to be at least partially nomadic), this species' core habitat is mixed swamp-forest and peatswamp. Historically, this habitat was extensive along both coasts of the Thai-Malay Peninsula and widespread along the coasts of Borneo and Sumatra as well as inland along the fringes of large rivers. Over the past several decades, it has been substantially reduced in extent and become fragmented.
Records from Thailand are very sporadic and the species may now be confined to Phra Thong. In Peninsular Malaysia, there are no modern records from the west coast where most suitable habitat has been cleared, and sightings on the east coast may largely refer to wandering birds/small flocks, with little suitable habitat away from Johor. Most habitat on Sumatra has now been cleared and there are very few contemporary records away from Way Kambas National Park (eBird 2022), while on Nias recent surveys failed to detected the endemic taxon T. f. melopogenys, despite searches in apparently suitable habitat, the authors noting that 'heavy levels of degradation...may have led to its severe endangerment' (Rheindt et al. 2020). On Borneo it is generally scarce (Mann 2008), but it is locally common in larger patches of suitable habitat (D. L. Yong in litt. 2016, eBird 2022).
Based on remote sensing data (Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein), the forest cover extent in this species' range reduced by 31-34% in the three generations (12.9 years; Bird et al. 2020) to 2022. This is assumed to be the minimum rate of decline for this species. Although it is a capable disperser (demonstrated by sporadic records in, e.g., Singapore and small forest blocks in Peninsular Malaysia [eBird 2022]), large flocks of this species seem to depend on large areas of lowland habitat. It also appears to be partially nomadic and may depend on a network of feeding sites that vary spatially and temporally, making it especially vulnerable to habitat losses. Consequently, the population is suspected to have declined by 30-40% in the last three generations. In the years 2017-2021, the rates of forest loss slowed slightly, to an equivalent reduction of 27-28% over three generations, with an ever-increasing percentage of the species' population occurring in protected areas. Consequently, the rate of population reduction in the future is suspected to be slower, at 25-35% over three generations.

Treron fulvicollis is confined to the Sundaic lowlands, where it is known from south Tenasserim, Myanmar, peninsular Thailand (recorded only from Ko Pratong Island in the last fifty years [Anon. 2003, eBird 2022]), Sabah, Sarawak and Peninsular Malaysia, Singapore (non-breeding visitor), Brunei (very uncommon) and Kalimantan (where not uncommon) and Sumatra (including the Riau and Lingga archipelagos, Bangka, Belitung, Siberut and Nias islands), Indonesia (BirdLife International 2001).

It occurs in freshwater swamp forest, peatswamp forest, mangroves, coastal forest, open scrub and secondary growth, including wooded gardens, to 200 m. Non-breeders occasionally visit higher elevation dry land forests.

Lowland forests in Sundaland have been dramatically reduced in extent and quality by human activities such as logging and plantation agriculture (especially oil palm) and this is considered the principal threat to this forest-dependent species. Forest fires are also a more moderate threat. It may also locally be impacted by hunting, although this is unlikely to be driving substantial population declines.

Conservation Actions Underway
None is known but it occurs in numerous protected areas.

Conservation Actions Proposed
Survey to assess the population size. Regularly monitor at certain sites throughout its range to determine population trends. Investigate the extent and impact of hunting. 
Protect remaining areas of primary forest and significant areas of secondary or logged forest throughout its range, in particular coastal lowland forest which are rare in Malaysia and Indonesia and are threatened by conversion to agricultural land (D. L. Yong in litt. 2016). Control hunting where possible, perhaps using awareness campaigns. 

Text account compilers
Berryman, A.

Contributors
Yong, D.

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Recommended citation
BirdLife International (2024) Species factsheet: Cinnamon-headed Green-pigeon Treron fulvicollis. Downloaded from https://datazone.birdlife.org/species/factsheet/cinnamon-headed-green-pigeon-treron-fulvicollis on 22/11/2024.
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 22/11/2024.