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

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 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). 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). The population size has not been quantified, but it is not believed to 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). For these reasons the species is evaluated as Least Concern. 

Population justification
Due to the apparent rarity of C. aeruginosus heinrichi on Halmahera and Bacan, when considered separately this subspecies was placed in the band 6,000-15,000 mature individuals. The species as now defined contains additional subpopulations on Obi, Buru and Seram where the species has been encountered in a wider range of habitats and across a greater elevational range (Thibault et al. 2013, Mittermeier et al. 2013). On Obi was it was described as reasonably common and tolerant of moderate habitat disturbance (Mittermeier et al. 2013) while on Seram it was uncommon to fairly common with around 2 birds per day encountered in montane primary forest (A. Reeve in litt. 2016). Despite the fact that the overall population size has not been quantified the species is therefore not believed to approach the thresholds for Vulnerable under the population size criterion.

Trend justification
The population is inferred to be undergoing a continued decline owing to forest clearance and degradation. Vetter (2009) used remote sensing techniques to track the rate and spatial pattern of forest loss in the North Maluku Endemic Bird Area (EBA) between 1990 and 2003, and project rates of deforestation over the next three generations for restricted range bird species found in this region, with consequent recommendations for category changes on the IUCN Red List. This study estimated the rate of forest loss within the elevation range of Moluccan Cuckoo in the EBA to be c.5.7% between 1990 and 2003, and projected the loss of c.6% of forest in its range in the EBA over the next three generations (estimated to be 12.6 years, based on an estimated generation length of c.4.2 years). The species, however, appears to show greater tolerance for degraded habitat away from the North Maluku EBA and there is uncertainty over deforestation rates in parts of the species's range not covered by Vetter's (2009) study, such as Buru and Seram. Given this uncertainty, it is suspected that the species has been declining at a rate between 5-10% over the past 12 years. It is suspected that this decline is ongoing based on the assumption that degradation and loss of forested habitat throughout the range of the species continues.

Cacomantis aeruginosus is found on the islands of Halmahera, Bacan, Obi, Ambon, Seram and Buru, Indonesia (Mittermeier et al. 2013, Thibault et al. 2013, del Hoyo and Collar 2014). 

The subspecies C. a. heinrichi (Halmahera and Bacan) is known from relatively few records and appears to be restricted to primary or selectively-logged forest between 800-1500 m above sea level (Tebb et al. 2008). The nominate race occurs across a wider elevational range: on Obi it occurs from sea level to at least 1150 m and utilises lowland swamp-forest, dense secondary and montane forest (Mittermeier et al. 2013).

It may be vulnerable to forest loss within its range owing to the expansion of small-holder farming and subsistence logging.

Conservation Actions Underway
None are known.

Conservation Actions Proposed
Survey for this species and calculate density estimates in order to revise its global population estimate. Assess its dependence on forest. Calculate rates of forest loss using remote sensing of satellite images. Protect areas of suitable habitat and safeguard against encroachment and degradation.

Text account compilers
Dutson, G., Bird, J., Wheatley, H., Martin, R, Taylor, J., Symes, A., Benstead, P.

Contributors
Dutson, G., Eaton, J., Reeve, A.H.R.

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Recommended citation
BirdLife International (2024) Species factsheet: Moluccan Cuckoo Cacomantis aeruginosus. Downloaded from https://datazone.birdlife.org/species/factsheet/moluccan-cuckoo-cacomantis-aeruginosus 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.