Emerald Starling (Coccycolius iris – BirdLife species factsheet) is currently classified as Data Deficient due to a prior lack of knowledge on its ecology, movements and population size.
C. iris is known from west and south-east Guinea, Sierra Leone and west-central Côte d’Ivoire. It is found in orchard bush and wooded and open savanna, where it keeps to the tops of tall trees, often using dead trees for perches (Hall and Moreau 1970, P. Robertson verbally 1998). It is considered to be localised and generally scarce (Butchart 2007), although large flocks are sometimes recorded (Demey 2003). The population size of this species has not previously been quantified. The population trend is unknown, although habitat modification and capture for the wild bird trade have been considered to be potential threats.
A recent study by G. Buchanan (in prep) has provided new information on the range and status of C. iris. Between 2012 and 2014, surveys were carried out in Sierra Leone and Guinea and the results were used to model the species’s distribution and estimate population size. The results of this study predict that the range of C. iris is smaller in the west, but potentially more extensive in the east, than was previously known. The potential distribution was estimated at 78,500km2 or 121,500 km2, depending on the threshold used by the model to determine suitable habitat. The population density was found to be 5.13 birds per km2. Based on these figures for the predicted distribution and population density, the total population of C. iris was estimated to be 623,295 or, more conservatively, 402,705 individuals.
Population trends of C. iris remain unknown. Habitat modification such as large-scale woodland clearance for open-cast mining and agriculture remains a potential threat. Exploitation of Lake Sonfon in Sierra Leone is thought to pose a particular threat as this area is an important site for the species. The impact of capture for trade is still unknown.
The results of the new study indicate that C. iris has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion. The estimated population size is very large, and hence does not approach the thresholds for Vulnerable under population size criteria. The population trend is difficult to determine because of uncertainty over the impacts of habitat modification and trapping on population sizes, but rapid declines are probably unlikely. It is therefore proposed that C. iris is listed as Least Concern.
Additional information and comments on this proposal are welcomed.
Butchart, S.H.M. 2007. Emerald (Iris Glossy) Starling Coccycolius iris. Bulletin of the African Bird Club 14(2): 148.
Buchanan, G. in preparation. Re-assessing the Red-List status of the Data-Deficient Emerald starling Coccycolius iris. RSPB report.
Demey, R. 2003. Recent reports. Bulletin of the African Bird Club 10(2): 129-141.
Hall, B.P. & Moreau, R.E. 1970. An atlas of speciation in African passerine birds. British Museum (Natural History), London.