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Mount Karthala White-eye Zosterops mouroniensis
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This species is classified as Vulnerable since it has a very small range, confined to the top of an active volcano. The population is suspected to have declined since 1985 owing to a reduction in the Area of Occupancy as a result of volcanic activity, however the extent of habitat is expected to recover through natural regeneration so the species is not suspected to be undergoing a continuing decline. Nevertheless, the limited range and small population of this species render it extremely susceptible to future threats, most notably, a serious eruption. In such a case the species may warrant uplisting to Critically Endangered.

Taxonomic source(s)
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

13 cm. Medium-sized, warbler-like bird. Dull olive-brown upperparts with narrow white eye-ring. Yellowish-green underparts, brighter on throat and vent. Similar spp. Madagascar White-eye Z. maderaspatanus much brighter yellow below and greener above, but range rarely overlaps. Voice Noisy, with continual contact by typical buzzy white-eye calls and twitterings. Hints Gregarious, restless.

Distribution and population
Zosterops mouroniensis is restricted to, although common in, the upper reaches of the actively volcanic Mt Karthala, Grand Comoro (= Ngazidja), Comoro Islands. In 1988, the population was estimated to be "a few thousand birds at most" (Louette et al. 1988). Surveys in 2005 indicated that densities had remained stable since 1985 (C. Marsh in litt. 2007). However, the population is suspected to have declined since 1985 owing to a reduction in the extent of habitat as a result of volcanic activity. The extent of habitat is expected to recover through natural regeneration (C. Marsh in litt. 2007, 2009).

Population justification
The range estimate of 2,500-9,999 individuals is supported by recent surveys that estimated densities of 1,500 birds/km2, suggesting the population size is towards the high end of this range (C. Marsh in litt. 2007). This estimate equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification
Surveys in 2005 indicated that densities had remained stable since 1985 (C. Marsh in litt. 2007). However, the population is suspected to have declined at an unknown rate since 1985 owing to a reduction in the extent of habitat as a result of volcanic activity. The extent of habitat is expected to recover through natural regeneration (C. Marsh in litt. 2007).

It is confined to a single small area of Philippia heath woodland around the crater of Mt Karthala. During surveys in 2005 is was recorded at 1,870-2,180 m, with a few individuals encroaching into the upper limits of the forest (C. Marsh in litt. 2007). It can be seen in large groups foraging in bushes or flying just over vegetation, and has been observed with Z. maderaspatanus (Louette et al. 1988, C. Marsh in litt. 2007). It is a fruit- and insect-eating bird. One nest has been found 4 m above the ground and another 1 m from the top of a Philippia bush.

Large patches of heath near the summit of Mt Karthala were burnt in 1958, probably as a result of volcanic activity (Benson 1960). Following eruptions in 2005, a reduction in the area of Philippia habitat was observed, particularly within and just around the crater above 2,500 m (C. Marsh in litt. 2007). A future eruption could be catastrophic for the species. Tree-heath is threatened by browsing cattle and by fire used to stimulate growth of palatable shoots (Safford 2001). In 2005, cattle grazing was judged to be limited in extent (C. Marsh in litt. 2007). With this island's large, increasing human population (Louette et al. 1988), clearance of forest for agriculture is occurring on all but the poorest soils. Since 1983, intact forest may have declined by over 25% as agriculture has advanced steadily up the slopes of Mt Karthala towards the habitat of this species. Secondary forest in the agricultural belt is dominated by exotic plants, particularly strawberry guava Psidium cattleianum, which could spread into and degrade remaining native forest. If plans to build a road to Mt Karthala's crater are resurrected, exploitation and fragmentation of the forest, and the spread of exotic species, could be accelerated (Safford 2001). Introduced rats may act as nest predators or food competitors (Safford 2001). The lower boundary of Philippia, and thus the species's range, may be pushed upwards by an expansion of the forest owing to a future rise in global temperatures (C. Marsh in litt. 2007).

Conservation Actions Underway
A protected area (national park, biosphere reserve or resource management area) on Mt Karthala has been proposed, but has not yet materialised (Louette and Stevens 1992, Safford 2001). Conservation Actions Proposed
Carry out surveys to monitor population trends. Monitor rates of habitat clearance and degradation. Research the ecology of this species to aid conservation plans. Create a protected area on Mt Karthala to encompass the known range of this species, and develop a management strategy (Louette and Stevens 1992, Safford 2001). Develop an environmental education programme on the island (Louette and Stevens 1992). Encourage locally-organised ecotourism as an alternative source of income for inhabitants of the Mt Karthala area (Safford 2001).

Benson, C. W. 1960. The birds of the Comoro Islands: results of the British Ornithologists' Union Centenary Expedition 1958. Ibis 103b: 5-106.

Louette, M.; Stevens, J. 1992. Conserving the endemic birds on the Comoro Islands, 1: general considerations on survival prospects. Bird Conservation International 2: 61-80.

Louette, M.; Stevens, J.; Bijnens, L.; Janssens, L. 1988. Survey of the endemic avifauna of the Comoro Islands. International Council for Bird Preservation, Cambridge, U.K.

Safford, R. J. 2001. Comoros. In: Fishpool, L.D.C.; Evans, M.I. (ed.), Important Bird Areas in Africa and associated islands: Priority sites for conservation, pp. 185-190. Pisces Publications and BirdLife International (BirdLife Conservation Series No.11), Newbury and Cambridge, UK.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Benstead, P., Ekstrom, J., Pilgrim, J., Shutes, S., Symes, A., Taylor, J., Warren, B.

Marsh, C.

IUCN Red List evaluators
Butchart, S., Taylor, J.

Recommended citation
BirdLife International (2016) Species factsheet: Zosterops mouroniensis. Downloaded from on 28/10/2016. Recommended citation for factsheets for more than one species: BirdLife International (2016) IUCN Red List for birds. Downloaded from on 28/10/2016.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Key facts
Current IUCN Red List category Vulnerable
Family Zosteropidae (White-eyes)
Species name author Milne-Edwards & Oustalet, 1885
Population size 1500-7000 mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 70 km2
Country endemic? Yes
Links to further information
- Additional Information on this species