Metabolus rugensis 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Monarchidae

Scientific Name: Metabolus rugensis (Hombron & Jacquinot, 1841)
Common Name(s):
English Chuuk Monarch, Truk Monarch
Taxonomic Source(s): del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Identification information: 20 cm. Large, striking flycatcher. Adult male nearly all white, with glossy blue-black face and throat and black primary tips. Some are tinged pale salmon or buff below. Females dark slate, most individuals blotched with rufous feathers retained from juvenile plumage. Juveniles bright rufous above, rufous-buff below with ill-defined, buff eyebrow. Similar spp. Juveniles similar to Caroline Reed-warbler Acrocephalus syrinx, but much brighter rufous above and with less defined supercilium. Voice No well-defined song. Calls include human-like whistles slurred up or down and plaintive, querulous u-waw, reflected in the local name. Hints Slow-moving and rather tame, but surprisingly difficult to see.

Assessment Information [top]

Red List Category & Criteria: Endangered C2a(ii) ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Collins, C., Dutson, G., Pratt, H. & Scott, D.
Facilitator/Compiler(s): Mahood, S., O'Brien, A., Shutes, S., Stattersfield, A., Taylor, J.
This species qualifies as Endangered because it has a very small population, which appears to be in rapid decline owing to the loss of habitat within its small range. If this loss of habitat becomes chronic and causes the population to become severely fragmented then it may be uplisted to Critically Endangered.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Metabolus rugensis is widely but sparsely distributed on all, or nearly all, of the high lagoon islands, as well as some of the outer reef islets of Chuuk (= Truk), Federated States of Micronesia, with highest densities reported from Tol South. It has probably never been abundant in historic times. In 1984, numbers were estimated at 2,168 (Engbring et al. 1990). Observations in 2001 suggested that it had declined to lower population densities (G. Dutson in litt. 2003). On Tol South, no birds were found in a visit in 1991 and only 3-4 birds in 1993, although birds were seen again in 2005 (C. Collins in litt. 2005). It was thought to have been extirpated from Weno after a major fire destroyed the patch of forest where it was uncommon in the 1970s (H. D. Pratt in litt. 1994); however, two males were seen in Sopo Forest in 2005 (C. Collins in litt. 2005). The species now appears to be rare on Weno (C. Collins in litt. 2011), and according to local people it is becoming rarer on Tol South (D. Scott in litt. 2011). It was not found in 2010 in an area on Dublon Island where it had been seen in 2008 (D. Scott in litt. 2011).

Countries occurrence:
Micronesia, Federated States of
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:500
Continuing decline in extent of occurrence (EOO):YesExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:11-100Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):435
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The population estimate of 1,000-2,499 individuals is derived from Engbring et al. (1990) and H. D. Pratt in litt. (1994).

Trend Justification:  A population estimate in 2001 (G. Dutson in litt. 2003) suggested that the species had declined from the 1984 estimate (Engbring et al. 1990). The species is now thought to be rare on Weno (C. Collins in litt. 2011), and according to local people it is becoming rarer on Tol South (D. Scott in litt. 2011). Furthermore, it was not recorded in an area on Dublon Island in December 2010 where it had been seen in December 2008 (D. Scott in litt. 2011). On the basis of this information the population is suspected to be in declining at at least 1-9% over three generations (13 years).
Current Population Trend:Decreasing
Additional data:
Number of mature individuals:1000-2499Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It occurs at highest densities in small patches of upland native forest, but is also found in well-developed stands of mangrove, thickets, atoll strand and (rarely) plantations along scrubby slopes, often covered by hibiscus Hibiscus tiliaceus or along steep ridges or cliffs (Engbring et al. 1990, D. Scott in litt. 2011). It favours areas with a thick, leafy understorey where it is found in small family groups gleaning insects, lizards and other prey from the foliage (Engbring et al. 1990). It appears to be strongly territorial, nesting in trees with dense foliage and nesting has been recorded from April to July (Engbring et al. 1990).

Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):4.2
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): It is likely to have declined dramatically in the 1940s, owing to extensive agricultural development during the Japanese administration, and may still be gradually declining, most likely due to the rapidly expanding human population (Engbring et al. 1990) and consequent further loss of its habitat. Although it shows some flexibility in its habitat requirements, the species appears to prefer native forest, which on Tol South is now restricted to the summit plateau (D. Scott in litt. 2011). There are also second-hand reports that the species has been targeted with slingshots on Weno (C. Collins in litt. 2011).

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
This species is the state bird of Chuuk and may obtain some conservation benefit from this recognition.

Conservation Actions Proposed
Carry out comprehensive surveys to assess the current population size. Conduct regular surveys to monitor population trends (Engbring et al. 1990). Protect forest habitat, including the small patches of native forest remaining on the high islands, the atoll forest on the outer reef islands, and the more extensive stands of mangrove (Engbring et al. 1990). Assess the threat posed by direct persecution. Conduct awareness-raising activities to discourage persecution.

Citation: BirdLife International. 2016. Metabolus rugensis. The IUCN Red List of Threatened Species 2016: e.T22707227A94111958. . Downloaded on 18 June 2018.
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