Metabolus rugensis 


Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Monarchidae

Scientific Name: Metabolus rugensis
Species Authority: (Hombron & Jacquinot, 1841)
Common Name(s):
English Chuuk Monarch, Truk Monarch
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: 2012
Date Assessed: 2012-05-01
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:
2008 Endangered (EN)
2004 Endangered (EN)
2000 Endangered (EN)
1996 Endangered (EN)
1994 Endangered (EN)
1988 Threatened (T)

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). It subsequently appears to have become much rarer according to a population estimate in 2001 (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). In addition, the species was not successfully located in December 2010 in an area on Dublon Island where it had been seen in December 2008 (D. Scott in litt. 2011).

Countries occurrence:
Micronesia, Federated States of
Continuing decline in area of occupancy (AOO): Yes
Extreme fluctuations in area of occupancy (AOO): No
Estimated extent of occurrence (EOO) - km2: 80
Continuing decline in extent of occurrence (EOO): Yes
Extreme fluctuations in extent of occurrence (EOO): No
Number of Locations: 11-100
Continuing 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). This equates to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.

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 rapid decline overall.
Current Population Trend: Decreasing
Additional data:
Number of mature individuals: 600-1700 Continuing decline of mature individuals: Yes
Extreme fluctuations: No Population severely fragmented: No
No. of subpopulations: 1 Continuing decline in subpopulations: Yes
Extreme fluctuations in subpopulations: No All 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).

Systems: Terrestrial
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. 2012. Metabolus rugensis. The IUCN Red List of Threatened Species 2012: e.T22707227A39421028. . Downloaded on 30 May 2016.
Disclaimer: To make use of this information, please check the <Terms of Use>.
Feedback: If you see any errors or have any questions or suggestions on what is shown on this page, please provide us with feedback so that we can correct or extend the information provided