Justification of Red List Category
This species appears highly restricted and is estimated to have a small population size, but there appear few threats to the species and as such the population is assumed to be stable. Given the likely small population size the species is evaluated as Near Threatened.
Monachella coultasi has apparently only been recently recorded from a single river in east New Britain, with historic records from an additional four rivers (G. Dutson in litt. 2016). While the extent of occurrence of the split species is calculated at 25,107 km2, the actual occupied range is a tiny percentage of this and arranged linearly. The entire length of suitable sections of rivers in the species’ apparent range is below 100 km, which at the estimate of 1 pair per 200 m (Boles 2016) (which is likely to be at maximum occupancy, and was not made on New Britain) indicating that the population falls in the range 1,000-2,499 individuals, equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
Restricted to fast-flowing and braided rivers in eastern New Britain, Papua New Guinea.
Confined to forest along rivers but appears to be tolerant of habitat disturbance as it occurs in degraded areas.
Threats to the species are not well known, and it utilises sections of streams with open space around as it occurs within small landslips (Dutson 2011). However, the response of the species to the removal of streamside vegetation is not documented, nor is it clear why it appears so restricted on New Britain. Rivers in the area which the species occurs are used as significant access routes and there is evidence of clearing along their banks by small-holders for agriculture (Hansen et al. 2013). There does not appear to be any particular reason to infer that the population is declining, and on New Guinea Monachella muelleriana is often found on rivers in degraded habitat.
Text account compilers
Butchart, S. & Ekstrom, J.
BirdLife International (2019) Species factsheet: Monachella coultasi. Downloaded from http://www.birdlife.org on 24/03/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/03/2019.