Data Zone
Justification of Red List category
This species's population size is unknown, but is suspected to be small to moderately large. The size of the largest subpopulation on Makira is also unknown and may be very small, but is suspected to be larger than 1,000 mature individuals. The population size has recently increased on Makira following the cessation of hunting with guns, but the rate of deforestation has increased across the species's range over the past few years, so an ongoing decline is inferred. For these reasons, the species is listed as Near Threatened.
Population justification
On Guadalcanal, an expedition in 1953 failed to find it (Cain and Galbraith 1956) and there are few recent records (G. Dutson pers. obs. 1997-8, K. D. Bishop in litt. 1999). Hunters at Komarindi reported shooting just one of this species for every 20 D. rubricera (van Oosten and Wyant 1999). On the little-studied island of Malaita, it is known from just one specimen and was seen twice in 1990 (Mayr 1931, Lees 1991, P. Scofield in litt. 1999). On Ugi and Ulawa, it was recorded as abundant in 1953 (Cain and Galbraith 1956). There have been no recent records on Ulawa or the Three Sisters, and it may be extinct on these small islands (G. Dutson pers. obs. 1997-8). A flock of eight individuals was recorded on Ugi in 2015 (Gregory 2015).
On Makira, it was recorded as common from coastal to ridge forest in 1953 (Cain and Galbraith 1956). More recent records include single birds and congregations of up to 20 birds around Hauta (Lees 1991, Buckingham et al. 1995, Gibbs 1996, G. Dutson pers. obs. 1997-8, R. James in litt. 1999). Surveys in 2006 found that the species was fairly common between elevations of 800-900 m (Danielsen et al. 2010). A total of 65 individuals were recorded during surveys in lowland forest in Kahua in 2012 (Davies et al. 2015). During surveys in 2015-2016, the species was observed frequently in flocks of 15-25 individuals in the lowland and hill forests in the south of the island (Mittermeier et al. 2018). The population on Makira appears to have rebounded following controls on guns, and many more individuals were observed in the lowlands in 2016 than had been in previous years (G. Dutson in litt. 2016, Mittermeier et al. 2018). The population on the island is suspected to be greater than 1,000 mature individuals (G. Dutson in litt. 2016).
No direct estimates of population size or population density are available. According to remote sensing data, there were approximately 10,072 km2 of tree cover with at least 30% canopy cover in the species's extant and possibly extinct range in 2010 (Global Forest Watch 2021). Based on the minimum and first quartile recorded densities of congeners (1.1 and 14 individuals/km2, respectively), the area of tree cover stated above, and assuming that tree cover to be 25-40% occupied, the population size may be estimated to fall in the range 2,700 - 59,000 individuals, roughly equating to 1,800 - 39,000 mature individuals. However, there have been few recent records from Guadalcanal, Malaita or Ugi, so the species may be rare on these islands, and no recent records from Ulawa and the Three Sisters, where the species may be extinct. Assuming a minimum of 50 mature individuals on each of Guadalcanal and Malaita, 10 on Ugi, and none on Ulawa or the Three Sisters, the minimum population size is placed at 610 mature individuals. Given the paucity of recent records from Guadalcanal and Malaita, the true population size is likely to fall towards the lower end of this estimate, but the population on Makira is suspected to be greater than 1,000 mature individuals (G. Dutson in litt. 2016), so a best estimate is here placed within the range 1,100 - 19,999 mature individuals.
It is assumed that the populations on Guadalcanal, Malaita and Makira are distinct subpopulations. Assuming that the subpopulation on Makira is the largest, based on the paucity of recent records from other islands, the minimum size of the largest subpoulation is placed at 500 mature individuals based on the area of tree cover and the method above, but it is suspected to be more than 1,000 mature individuals (G. Dutson in litt. 2016). Using the above method and the largest area of tree cover on one island (3,710 km2 on Guadalcanal), the maximum size of the largest subpopulation is placed at 15,000 mature individuals.
Trend justification
From 2001 to 2019, an estimated 7% of tree cover with at least 30% canopy cover was lost from across the species's range (Global Forest Watch 2021). The rate of forest loss was significantly higher over the period 2014-2019, with approximately 4% lost over this period alone. The population size is thus inferred to be undergoing a continuing decline. Based on the above rate of tree cover loss, 7% of tree cover is estimated to have been lost from the species's range over the past 20 years (three generations), and 8-14% is projected to be lost over three generations into the future.
This species appears to be tolerant of moderately degraded forest, although this may be an artefact of increased detectability (G. Dutson in litt. 2016). However, it avoids cacao plantations (Mittermeier et al. 2018), and is reliant on fruiting trees, so forest loss is likely to affect its population size. There may also be an additional population impact of forest degradation caused by logging (G. Dutson in litt. 2021). The population on Makira appears to have rebounded since 2003 following controls on guns, and many more individuals were observed in the lowlands in 2016 than had been in previous years (G. Dutson in litt. 2016, Mittermeier et al. 2018). This pattern may have been replicated in Guadalcanal and Malaita.
The population size is therefore suspected to have undergone an increase over the past three generations, but there is inferred to be a slow continuing decline owing to ongoing forest loss, and a reduction of less than 20% is suspected to take place over the next three generations.
Ducula brenchleyi is endemic to Guadalcanal, Malaita and Makira (= San Cristobal), including the satellite islands of Ulawa, Ugi (= Uki Ni Masi) and Three Sisters, Solomon Islands. There have been no recent records on Ulawa or the Three Sisters, and it may be extinct on these small islands (G. Dutson pers. obs. 1997-8).
It is usually recorded in primary forest but also occurs in fruiting trees in degraded forest and gardens (Cain and Galbraith 1956, Buckingham et al. 1995, R. James in litt. 1999, G. Dutson in litt. 2016). It avoids cacao plantations (Mittermeier et al. 2018). Records have been from sea-level to 700 m, but has been reported by local villagers on Guadalcanal as occurring in mist-forest (Cain and Galbraith 1956, Buckingham et al. 1995). It feeds on fruits, including figs and Canarium solomonense (R. James in litt. 2021). It appears to be nomadic (G. Dutson pers. obs. 1997-8, J. Waihuru verbally 1998, R. James in litt. 1999): at Hauta, birds congregate to feed on banyan figs for about a week until the fruit is finished and then disperse, often over large distances (Cain and Galbraith 1956, J. Waihuru verbally 1998, R. James in litt. 1999).
This large pigeon has been hunted by villagers on Makira and elsewhere across its range. Firearms were banned in the Solomon Islands in 2003, so hunting pressure has likely declined across most of the range of this species, and the ban seems to have allowed the species to rebound, with many more birds seen in the coastal lowlands of Makira than previous years (G. Dutson in litt. 2016).
Forest is being degraded and lost through commercial logging across the species's range, and this may particularly affect this species due to its reliance on fruiting trees. The rate of forest loss across the species's range has increased in recent years (Global Forest Watch 2021). Most accessible forests in the Solomon Islands have been logged (Katovai et al. 2015). On Makira, logging is extensive in the lowlands and is poorly-regulated (Danielsen et al. 2010).
Conservation Actions Underway
The effects of hunting pressure and the foraging behaviour of large pigeons has been studied briefly at Hauta. The forests around Hauta are part of an integrated conservation and development programme (R. James in litt. 1999). Community-based education programmes have taken place around Komarindi (van Oosten and Wyant 1999).
38 cm. Large, dark, slender imperial-pigeon. Dark grey above shading into pale grey on head. Dark vinous underparts, becoming chestnut on belly to undertail-coverts. In flight, grey with contrasting chestnut underwing-coverts. Similar spp. Island Imperial-pigeon D. pistrinaria is pale grey with paler spectacles, green-grey upperparts and chestnut only on the undertail-coverts. Yellow-legged Pigeon Columba pallidiceps has pale head, glossy black body and yellow legs. Voice Deep, smooth, prolonged coo, rising in pitch then falling ooloooo. Hints Usually seen flying overhead or in mixed pigeon flocks (often with Red-knobbed Imperial-pigeon D. rubricera and D. pistrinaria) in fruiting trees.
Text account compilers
Wheatley, H.
Contributors
Bishop, K.D., Dutson, G., James, R., Scofield, P., Waihuru, J., Stattersfield, A., Ekstrom, J., Derhé, M., Mahood, S., Van der Ploeg, J., O'Brien, M. & Brusland, S.
Recommended citation
BirdLife International (2024) Species factsheet: Chestnut-bellied Imperial-pigeon Ducula brenchleyi. Downloaded from
https://datazone.birdlife.org/species/factsheet/chestnut-bellied-imperial-pigeon-ducula-brenchleyi on 23/11/2024.
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 23/11/2024.