Justification of Red List Category
The species is considered to have a very small population, estimated to be below 250 mature individuals, but which appears to be stable. Any indication of a decline would warrant listing as Critically Endangered, however in the absence of a decline Yap Cicadabird is evaluated as Endangered under Criterion D1.
E. nesiotis appears to have always been considered rare or uncommon and Engbring et al. (1990) estimated that the total population was just 273 birds, roughly equivalent to 180 mature individuals. The species is found widely across the island but with four times the density in forest compared to savanna (Engbring et al. 1990). It is still possible to locate the species during short visits to the island (e.g. Morris 2016), but there is no more recent population estimate or trend assessment.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
Edolisoma nesiotis is endemic to Yap, Federated States of Micronesia. Surveys in the 1980s found the species widely spread but at low density, and the species was recorded in both forest and savanna habitat.
During the Micronesian Forest Bird surveys in the 1980s (Engbring et al. 1990) the species was recorded in both forest and savanna habitat, but at four times the density in forest than savanna, and sightings away from forest appear very rare (G. Dutson in litt. 2016). It is suspected that the species is highly dependent on remaining forest for much of its life cycle, but is likely to roam over relatively large areas. This also supports the idea that this is a low density species with a small total population size.
Loss of habitat from fire is a threat as local people set fire to large areas of savanna during the dry season (B. Raynor in litt. 1995). The species is also at risk from the accidental introduction of alien species, particularly brown tree snake Boiga irregularis which has caused the extinction of many bird species on Guam (to USA) (Engbring et al. 1990).
Conservation Actions Underway
Nothing targeted to the species is known.
Conservation Actions Proposed
Obtain a new population estimate and carry out regular monitoring to determine trends. Educate local people about the effects of dry-season fires on the species. Limit the use of fire in the dry season. Take measures to prevent the introduction of B. irregularis to Yap.
24 cm. A distinctive cicadabird, formerly part of the Slender-billed group of species, being long-tailed and narrow-bodied with a relatively long bill. Males are a fairly uniform dark slate grey with a smudged darker grey face mask. Females have barred flanks and rump and are rufous-brown above and pale rufous below.
Text account compilers
Ekstrom, J., Martin, R, Butchart, S.
Dutson, G., Trainor, C.
BirdLife International (2019) Species factsheet: Edolisoma nesiotis. Downloaded from http://www.birdlife.org on 24/08/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 24/08/2019.