Data Zone
Justification of Red List category
A moderate to rapid population reduction is suspected based on an apparent reduction in the rate of reporting and the observation that the species may no longer occur on Narcondam Island. The rate of the reduction is highly uncertain, with the very rapid reductions from one analysis appearing unlikely, given the apparently similar proportion of observations reported from the majority of the speices's range over the time period in question. The population size is now suspected to exceed the threshold for listing as threatened under criterion C, it is suspected that there are considerably more than a thousand mature individuals in the largest subpopulation, and it is uncertain that the species is undergoing a continuing decline.
Population justification
No published direct population estimates are known. An approach using remote-sensed habitat data to infer the area of suitable habitat within the range at two points in time (6,105 km2 and 6,097 km2), then applying a predicted density value for the species (7.2 individuals/km2) gives an inferred population size of 44,029 and 43,570 individuals (Santini et al. 2019). However, the impact of hunting, noted to be severe in the Nicobar Islands (Pande et al. 2007) is not included in these values, hence the appropriate density may be considerably lower and the population correspondingly smaller. Given the extent of the range and the observation that the species is 'fairly common' even in agricultural landscapes on South Andaman (Gokulakrishnan et al. 2015), it is still believed that the overall population is more likely to exceed 10,000 mature individuals than not, but this is an uncertain estimate.
The number of subpopulations is uncertain: the species is considered monotypic but based on the range it is likely that there are a minimum of two separate subpopulations (Andaman and Nicobar Islands) at the very least. Potentially the species is a competent disperser, as noted for other Treron species, but there remains the possibility of much greater subdivision within the total population given the large number of occupied islands spread over a considerable distance.
Analysis of the relative proportion of eBird checklists including the species in each year between 2014-2019 suggest that the population is declining (State of India's Birds 2020). The rate of reduction is uncertain: the annual rate of change from the model was -10.81% plus or minus 6.67% (State of India's Birds 2020), which would equate to a reduction of 43-92% over three generations. However, there has been no indication of a severe decline from the extent of records that continue to be supplied to eBird (eBird 2021), and the proportion of lists on which the species is recorded also does not appear to have radically altered. Hence there is a very considerable uncertainty over the population trend. On Narcondam Island fieldwork in 2019-2020 failed to record the species (Naniwadekar et al. 2021), when it was present in 2007 (Pande et al. 2007).
Trend justification
State of India's Birds (2020) deduce from relative proportions of occurrence records on eBird checklists that this species may currently be declining at a rate of 10.81% annually, with a confidence interval of 6.67%. This would equate to a reduction of 43-92% over three generations. However, the extent of records that continue to be supplied to eBird does not suggest a rapid decline and the proportion of lists on which the species is recorded also appears similar (eBird 2021) creating considerable difficulty in interpreting the reported reduction. It is apparent that the sample size used for the initial time period is very small relative to the later period, and as such it is clear that no statistically significant trend can be detected from the raw data. A particular problem is a lack of any sufficiently severe threat: hunting impacts may be considerable in the Nancowry group but not elsewhere in the range (Pande et al. 2007, del Hoyo et al. 2020). The species may no longer be present on Narcondam: fieldwork in 2019-2020 failed to record it (Naniwadekar et al. 2021), while surveys in 2007 did report it (Pande et al. 2007). Overall, it is suspected that there is a moderate to rapid population reduction occurring, but not at the rates reported by State of India's Birds (2020) and this rate is most likely not sufficiently rapid to exceed the thresholds for listing as Vulnerable.
Treron chloropterus is found in the Andaman and Nicobar islands (India) (Gibbs et al. 2001, Rasmussen and Anderton 2005), and Coco Island (Myanmar) (del Hoyo et al. (2020). It is common or fairly common on south (Mount Harriet National Park, Chidiyatappu, Shoalbay), middle (Long Island) and north (Saddle Peak National Park) Andamans, as well as on Great and Little Nicobar, Car Nicobar and the Nancowry group (C. Sivaperuman in litt. 2016, GBIF.org 2021). It also occurs on Narcondam Island (Pande et al. 2007), though fieldwork there in 2019-2020 did not detect the species (Naniwadecker et al. 2021).
Occurs in evergreen forest and edge, feeds on figs and other fruit and breeds in February-March (Rasmussen and Anderton 2005).
Forest remains fairly extensive on the Andaman and Nicobar islands and the rate of forest cover loss is low at 2.3% between 2001-2019 (Global Forest Watch 2021), below 2% over three generations (13.4 years). Hunting has been reported to be a particular problem in the Nancowry Islands (Pande et al. 2007), but less of a threat in the Andaman Islands. The impact of the 2004 tsunami is unclear, though there have been suggestions that damaged forest areas are being developed rather than allowed to regenerate, although this species may actually benefit from the creation of more edge habitat and mixed plantation gardens.
Conservation and research actions underway
The Department of Environment and Forests, Andaman & Nicobar Islands has initiated steps to conserve the endemic and threatened bird species of Andaman and Nicobar Islands, and the Zoological Survey of India is monitoring the bird population of this archipelago (C. Sivaperuman in litt. 2016).
Conservation and research actions proposed
Conduct repeated surveys in areas within the species's range to generate density estimates on different islands to determine current distribution and abundance, as well as assess population trends. Assess hunting pressure on different islands and link this to the density estimates. Consider educational campaigns if hunting is found to be a significant threat. Ensure that the species is included in lists of key features in protected areas within the range and is considered in the management of these protected areas.
c. 27 cm. Medium-sized, green pigeon with a thick bill. The relatively long wings have prominent yellow edging on the flight feathers and a yellow bar across the coverts. Both sexes have a white forehead with a grey crown, as well as a bright yellow-green rump. Male has a fairly small dark maroon mantle patch with a green shoulder, all green in the female. Similar spp. T. affinis of southern India is smaller, has a much duller green rump and the male has entirely dark maroon back. Voice. Slightly nasal whistles, typically starting with two short steeply up- then downslurred notes.
Text account compilers
Martin, R.
Contributors
Praveen, J., Sivaperuman, C., Taylor, J., Symes, A. & Westrip, J.R.S.
Recommended citation
BirdLife International (2024) Species factsheet: Andaman Green-pigeon Treron chloropterus. Downloaded from
https://datazone.birdlife.org/species/factsheet/andaman-green-pigeon-treron-chloropterus on 22/12/2024.
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 22/12/2024.