Data Zone
Justification of Red List category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² or Area of Occupancy <2,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population size is suspected to be extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). For these reasons the species is evaluated as Least Concern.
Population justification
It is common in lowland forest in the Solomon Islands and New Britain (Blaber 1990, Kratter et al. 2001, Danielsen et al. 2010, Read 2013, Robbins and Robles Bello 2016, Davis et al. 2018, Callaghan et al. 2019). In a study by Davis et al. (2018) involving 415 hours of bird surveys on New Britain, this vocal species had the highest encounter rate of any bird (Davis et al. 2018, R. Davis in litt. 2020). No population density estimates are available, but the population size is suspected to be greater than 10,000 mature individuals (Buchanan et al. 2008, Davis et al. 2018).
The species has a large range, with an estimated 68,400 km2 of tree cover with at least 30% canopy cover within its range in 2010 (Global Forest Watch 2021). Although this area of tree cover is likely to include oil palm plantations, the species has been recorded as common in the lowlands in a number of surveys across its range, so the population size is likely to be very large. Based on the first quartile and median recorded densities of congeners (14.5 and 38 individuals/km2, respectively), the area of tree cover stated above, and assuming that tree cover to be 25-40% occupied, the population size is tentatively suspected to fall in the range 150,000 - 750,000 mature individuals.
The species has two subspecies, a fairly high dispersal ability, and occurs on a large number of islands. The number of subpopulations is suspected to fall within the range 2-20, based on a visual assessment of its range.
Trend justification
It is suspected to have declined in recent decades owing to ongoing clearance of lowland forest, at least in parts of its range (Buchanan et al. 2008). From 2001 to 2020, an estimated 9% of tree cover with at least 30% canopy cover was lost from across the species's range (Global Forest Watch 2021). The population size is thus inferred to be undergoing a continuing decline.
Based on the above rate of tree cover loss, 10% of tree cover is estimated to have been lost from the species's range over the past 22 years (three generations), and 11-16% is projected to be lost over three generations into the future. This species is tolerant of degraded forest, so its population size may not be declining at the same rate as deforestation, but it avoids oil palm plantations and more heavily degraded areas (Davies et al. 2015, Davis et al. 2018, G. Dutson in litt. 2021), so forest loss is likely to affect its population size. However, the population in the Solomon Islands appears to have become more easily detectable since the early 2000s following controls on guns (R. James in litt. 2021). Therefore, the population change over the past three generations is not known, but it is suspected to undergo a reduction of 1-16% over the next three generations.
Ducula rubricera is widely distributed in the Bismark Archipelago (Papua New Guinea), including New Britain, New Ireland, New Hanover, Watom, Duke of York, Lolobau, Umboi, and the island groups of Tabar, Lihir, Tanga and Feni, as well as Bougainville. It is also found on nearly all forested islands in the Solomon Islands, including Makira (San Cristobal), the New Georgia Islands (including Kolombangara and Tetepare), Santa Isabel, Malaita, Guadalcanal and Choiseul, but not on more remote islands such as Rennell (Dutson 2011, Weeks et al. 2017).
It inhabits primary and secondary lowland rainforest up to 500 m on New Britain, 700 m on New Ireland and 1,200 m on Guadalcanal and Kolombangara. It is common in both primary and degraded forests (Davis et al. 2018), and is often found at the forest edge, in cacao plantations, food gardens and even in urban areas (Blaber 1990, Davies et al. 2015, M. O'Brien in litt. 2021). However, it is thought to be very scarce or absent from more heavily deforested or degraded areas and oil palm plantations (Davies et al. 2015, Davis et al. 2018. G. Dutson in litt. 2021). It has a fairly high dispersal ability, but is not found on more remote islands (Weeks et al. 2017).
It is threatened by logging and forest conversion, particularly for conversion to oil palm plantations, across much of its range.
In 2002, all forest in New Ireland and West New Britain and most forest in East New Britain and Manus was allocated for industrial forestry, and New Britain alone accounted for approximately half of Papua New Guinea's timber exports (Bun et al. 2004). Regulations on the frequency of re-logging areas are being ignored (Nelson et al. 2014). On Makira, logging is extensive in the lowlands and is poorly-regulated (Danielsen et al. 2010). In the Solomon Islands, most accessible forests have been logged (Katovai et al. 2015).
Many areas of lowland forest in New Britain have been converted to oil palm plantations (Swartzendruber 1993, Buchanan et al. 2008). Much of the Bismarck Archipelago has been allocated as Special Agricultural Business Lease (SABL) areas, which would permit conversion to oil palm plantations. However, many of these areas appear to be unsuitable for oil palm, suggesting that they may be in place to facilitate commercial logging, under the pretext of oil palm development (Nelson et al. 2014, Bryan et al. 2015). Nevertheless, conversion to oil palm is likely to continue slowly in the region (Nelson et al. 2014).
Around 12% of forest cover in New Britain was lost between 1989 and 2000, with over 20% lost in the lowlands below 100 m (Buchanan et al. 2008). Since then, the rate of deforestation apparently slowed (B. Beehler in litt. 2016), and between 2002 and 2014, around 7.4% of forest on New Britain; 7.6% of forest on New Ireland; and 1.5% of forest on Bougainville, was logged or cleared (Bryan et al. 2015). On New Ireland, most lowland forest was lost before 1989, and the area converted to oil palm has been much smaller (Davis et al. 2018).
Other potential threats include hunting and road construction (Davis et al. 2018). The species has been hunted at low levels for subsistence on Makira (Davies 2014), but guns have now been banned in the Solomon Islands.
Conservation Actions Underway
It occurs in a number of protected areas, including community conserved areas.
40cm A large robust pigeon with pale upper back, head, neck, throat and breast (with a light pinkish flush except in Solomon islands race D. r. rufigula). Distinctive large reddish (occasionally yellowish) cere above bill. Wing-coverts iridescent emerald, bronzy or golden green with darker secondaries and tail feathers tainted bluish. Primaries blackish-blue; Underwing dull grey; Legs purplish-red. Juvenile resembles adult but lacking red cere. Similar spp. D. pacifica and D. myristricivora both superficially similar but with blackish ceres.
Text account compilers
Wheatley, H.
Contributors
Beehler, B.M., Bishop, K.D., Dutson, G., Wilkinson, R., Davies, T., Read, J., North, A., Ekstrom, J., Butchart, S., Mahood, S., Davis, R.A., Derhé, M., Brusland, S., O'Brien, M. & James, R.
Recommended citation
BirdLife International (2024) Species factsheet: Red-knobbed Imperial-pigeon Ducula rubricera. Downloaded from
https://datazone.birdlife.org/species/factsheet/red-knobbed-imperial-pigeon-ducula-rubricera 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.