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Zosterops modestus 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Zosteropidae

Scientific Name: Zosterops modestus
Species Authority: Newton, 1867
Common Name(s):
English Seychelles White-eye, Seychelles Grey White-eye
French Oiseau-lunettes des Seychelles
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: 10 cm. Small, dull olive-grey, warbler-like bird. Dark olive-grey upperparts with paler underparts and narrow, white eye-ring. Flank feathers sometimes fluffed open to impart pale grey flank-flash. Tiny, sharp bill. Voice Short, trilling nasal contact call and loud song.

Assessment Information [top]

Red List Category & Criteria: Vulnerable D1+2 ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Adam, P., Bristol, R., Hardcastle, J., Parr, S., Rocamora, G., Shah, N., Skerrett, A. & Gerlach, J.
Facilitator/Compiler(s): Ekstrom, J., Harding, M., Pilgrim, J., Shutes, S., Symes, A., Taylor, J., Warren, B., Ashpole, J & Westrip, J.
Justification:
Recent assessments have revealed no evidence of declines in habitat quantity or quality, and following intensive conservation work the population numbers more than 250 mature individuals. This species remains threatened, but has been downlisted to Vulnerable, because it still has an very small population and is found in only a very small number of locations.

Previously published Red List assessments:

Geographic Range [top]

Range Description:This species was thought to survive only in three tiny areas on Mahé, Seychelles and appeared to be declining inexorably towards extinction. In 1996, only 25-35 individuals were known (Rocamora 1997a). In 1997, a previously unknown population was discovered on Conception (Rocamora 1997a). In 1997, this island was estimated to hold "at least 250" individuals (Rocamora and Francois 1999), with c.50 more on Mahé (G. Rocamora in litt. 1999). The population on Conception was estimated at c.275 (244-336) individuals in 1999, at c.230 (189-266) in 2006, and c.340 in 2009 (Rocamora and Labiche 2009). The population on Mahé was estimated at c.50 birds in 1997 (G. Rocamora in litt. 2007) and at c.60 birds in 2006, and appeared to have slightly increased (G. Rocamora in litt. 2007) however it is now apparently decreasing with less than 40 birds censused in 2011-2013 (G. Rocamora in litt. 2014). The transfer of 37 individuals from Conception to Frégate Island in 2001 and 2003 resulted in the establishment of an estimated population of c.100 individuals there in 2007 (G. Rocamora in litt. 2007) with the latest estimate of approximately 150 individuals in 2010/2011 (G. Rocamora in litt. 2014).

Further translocations took place in 2007, when 25 birds were transferred to North Island, and 23 to Cousine (Rocamora and Henriette-Payet 2009). The North Island population has increased to approximately 100 individuals (Havemann and Havemann 2014). However the population on Cousine has apparently failed with no more than five individuals recorded there in 2013 (G. Rocamora in litt. 2014). Habitat quantity and quality are both increasing (due to rat eradications and restoration programmes in the islands where the species has been transferred) (G. Rocamora in litt. 2007). Results from a monitoring programme started since 1996 indicate a moderate increase in the total population (G. Rocamora in litt. 2007), which was estimated at c.400 birds in 2007 (Rocamora and Henriette-Payet 2009). A further estimate of 500-650 individuals was provided in 2013 (Safford and Hawkins 2013).

Countries occurrence:
Native:
Seychelles
Additional data:
Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:120
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:2-5Continuing decline in number of locations:No
Extreme fluctuations in the number of locations:No
Upper elevation limit (metres):600
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The total population is estimated at c. 500-650 individuals (Safford and Hawkins 2013), roughly equivalent to 330-430 mature individuals, placed here in the range of 250-999 mature individuals.

Trend Justification:  Habitat quantity and quality are both increasing (owing to rat eradications and restoration programmes in the islands where the species has been transferred) (G. Rocamora in litt. 2007). Results from the monitoring programme started since 1996 indicate a moderate increase in the population (G. Rocamora in litt. 2007).
Current Population Trend:Increasing
Additional data:
Number of mature individuals:250-999Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:Yes
No. of subpopulations:3Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No
No. of individuals in largest subpopulation:1-89

Habitat and Ecology [top]

Habitat and Ecology:Data from a recent study have suggested that the populations on Mahé and Conception are genetically isolated from each other (<1-2 migrants per generation), and that one does not represent a subsample of the other (Rocamora and Richardson 2003). They probably became isolated following the decline of the Mahé population, caused by human disturbance, 100-200 years ago, and retain different genetic fragments of the original population. The populations on both Mahé and Conception show low levels of genetic variability, comparable with the inbred island populations of other species (Rocamora and Richardson 2003). The ecology of two populations differs, with those on Conception holding territories in dense mixed woodland with an abundance of native fruiting trees, whereas birds on Mahé show flexibility in habitat choice (Rocamora and Richardson 2003).

On Mahé, it is predominantly found in man-made habitats, such as farms, residential areas, orchards, forest edge and mixed secondary forest (Rocamora 1997a), seeming to prefer particular exotic tree and shrub species (Mee 1996a, 1997, Rocamora 1997a). It principally eats insects, but also berries and nectar (Rocamora 1997b). On Mahé, its productivity in the 1990s was poor and recruitment very low, and it is possible that more widely dispersed populations have been lost in the past as productivity has declined (Mee 1997, Rocamora 1997a). It is a cooperative breeder, and on Conception breeding groups and clutch sizes tend to be bigger than on Mahé, with adult birds on Conception also showing low fidelity to particular nests. The trapping of birds has indicated a possible deficit of females on both Mahé and Conception, although the tape luring methods used are more likely to attract males (Rocamora and Richardson 2003).

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):3.5
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Loss of native vegetation - particularly large trees - may have been a factor in its decline (Gerlach 1996). However, there is no recent evidence of a significant decline in habitat quantity or quality (R. Bristol in litt. 2004), although invasion by alien plants continues on Mahé (J. Gerlach in litt. 2012). Nest-predation, by the introduced Black Rat Rattus rattus and Common Myna Acridotheres tristis, is the biggest threat on Mahé (Rocamora 1997a, Rocamora et al. 1999), while fire or disease are the main threats on Conception (Rocamora 1997a, Rocamora 1997b, G. Rocamora in litt. 2007). Conception was inhabited by R. norvegicus but an eradication operation was conducted in August 2007 (G. Rocamora in litt. 2007). On Mahé, abundant Seychelles Bulbul Hypsipetes crassirostris predates nests (Rocamora 1997a, 1997b, Rocamora and Francois 1999). Given its extremely small and fragmented range, the species is vulnerable to sudden stochastic events. Health screening done during 2007 transfers revealed the presence of a widespread Microfileria in the Conception population, although presence of such blood parasites in white-eye populations is common and normally not considered a significant threat (G. Rocamora in litt. 2007).

Conservation Actions [top]

Conservation Actions: Conservation and Research Actions Underway
None of the species's current sites on Mahé lie within the Morne Seychellois National Park (Mellanby et al. 1996). Intensive monitoring and research, is still underway mainly on Frégate, North and Cousine that host transferred populations (G. Rocamora in litt. 2007). In July 2000, the Ministere de l'Environnement started 'cat and rat' eradication on several islands including Frégate; subsequently 31 individuals were transferred to Frégate (Rocamora et al. 2002), an island which models suggest could support a population of more than 500 individuals (Rocamora et al. 2002). Almost all of the translocated birds have been regularly resighted, and by 2007 there were c.100 birds on the island. Breeding on Frégate extended beyond the normal breeding season indicating favourable conditions on the island. In 2007, 25 individuals were transferred from Conception to North Island, following successful rat eradication in 2005, whilst 20 were transferred from Conception and three from Mahé to Cousine (G. Rocamora in litt. 2007). Intensive habitat restoration has been carried out on North Island and Cousine, with the species attempting to breed there in November 2007 (G. Rocamora in litt. 2007). Work is underway to extend restored areas, with large areas of invasive Lantana and Clidemia being cleared (Havemann and Havemann 2014). Predator control and nest monitoring have been conducted on Mahé since 2006, and population monitoring is being carried out on the five islands where the species now occurs (G. Rocamora in litt. 2007)

Conservation and Research Actions Proposed
Continue to monitor population trends in all islands occupied by the species (both source and transferred populations). Create a protected area, and manage the habitat (Rocamora 1997a) to preserve the key population on Conception (Rocamora 1997a, N. J. Shah and S. Parr in litt. 1999). Encourage preservation of large garden trees in residential areas where the species is present on Mahé to help their short-term survival there (Gerlach 1996, Rocamora 1997a). Continue rat control and protection of nests in the two main Mahé subpopulations (G. Rocamora in litt. 2007). Consider translocation to other suitable predator and competitor-free islands (Gerlach 1996, Rocamora 1997a, N. J. Shah and S. Parr in litt. 1999, A. Skerrett in litt. 1999), G. Rocamora in litt. (2014) suggests at least two other transfers to rat-free islands. Continue to mix individuals from different source populations during translocations, thus recombining genetic variation in the species (Rocamora and Richardson 2003).


Citation: BirdLife International. 2016. Zosterops modestus. The IUCN Red List of Threatened Species 2016: e.T22714018A94397536. . Downloaded on 24 March 2017.
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