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Gymnomyza aubryana 

Scope: Global
Language: English
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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Passeriformes Meliphagidae

Scientific Name: Gymnomyza aubryana
Species Authority: (Verreaux & Des Murs, 1860)
Common Name(s):
English Crow Honeyeater
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: 41cm. Very large, crow-like honeyeater with orange facial wattles. Plumage all glossy black, bill grey above and yellow below, legs yellow and facial skin varies from yellow to red. Long rounded wings and fairly long neck and tail. Similar spp. New Caledonian Crow Corvus moneduloides and Melanesian Cuckoo-shrike Coracina caledonica have short dark bills and no bare facial skin - crow has short tail and cuckoo-shrike has long pointed wings. Voice Loud, repeated series of slightly varied phrases, typically a loud nasal note e.g. chong, followed by a descending series, e.g. tchku-tchku-... Harsh scolding tcharr or wa-wa similar to parrot or crow. Hints Listen at dawn.

Assessment Information [top]

Red List Category & Criteria: Critically 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): Barré, N., Chartendrault, V., Dutson, G., Ekstrom, J., Létocart, Y., Meresse, C., Meriot, J., O'Brien, M., Sirgouant, S., Spaggiari, J., Theuerkauf, J. & Stirnemann, R.
Facilitator/Compiler(s): Benstead, P., Bird, J., Derhé, M., Dutson, G., Ekstrom, J., Harding, M., Mahood, S., Stattersfield, A. & Ashpole, J
Justification:
This species is listed as Critically Endangered because it is believed to have an extremely small population, almost confined to one area in the south-east of New Caledonia. Its population trend is poorly-known but assumed to be declining because of forest degradation largely through an increase in anthropogenic fires.

Previously published Red List assessments:

Geographic Range [top]

Range Description:The species is endemic to New Caledonia (to France) where it is now mainly restricted to small populations scattered throughout the south of the island plus the Mt Panié massif in the north (Baudat-Franceschi 2013, Okahisa et al. 2016). Extensive surveys in 2001-2012 found the species at 81 locations (Chartendrault and Barré 2005, 2006, Okahisa et al. 2016). The total area where the bird has been recorded was estimated at <400 km2 (Létocart 2006) but a habitat suitability model suggests that 700 kmis suitable habitat (Okahisa et al. 2016). It appears to be localised and uncommon even in favoured areas, although c.18 pairs were known in the study area of Rivière Bleue, each occupying c. 1 km2 of forest, potentially extrapolated to 160 pairs across this protected area (Y. Létocart in litt. 1999). This estimate has been considered over-optimistic (N. Barré in litt. 1999), particularly if pairs require c. 1 km2, and may not be representative of the density elsewhere (Chartendrault and Barré 2005, 2006). Based on this home-range of 1 kmper pair and habitat modelling suggesting 700 km2 of suitable habitat, the total population is likely to be around 315–700 breeding pairs (Okahisa et al. 2016). This is lower than Ekstrom et al. (2002)'s suggestion of approximately 1000–3000 individuals which was based upon the assumption that all forests on ultramafic substrates provided suitable habitat for the species. A more precautionary but empirically-based estimate is 92 pairs within the Massif du Sud KBA (Angin 2011) plus a very few additional pairs scattered to the north.

Countries occurrence:
Native:
New Caledonia
Additional data:
Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:9900
Continuing decline in extent of occurrence (EOO):UnknownExtreme 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):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:Based on this home-range of 1 km2 per pair and habitat modelling suggesting 700 km2 of suitable habitat, the total population was estimated to be around 315–700 breeding pairs (Okahisa et al. 2016). However, a separate estimate for the southern subpopulation was 92 pairs within the Massif du Sud KBA (Angin 2011). There are likely additional pairs scattered to the north, especially around Mt Panié, but the total population is precautionarily assessed here as <250 mature individuals.

Trend Justification:  There has been insufficient baseline monitoring of this species's population to empirically assess population trends. It is likely to be suffering an ongoing habitat loss largely because of fires: the north-eastern ranges experienced a 30% decline in forest cover between 1989 and 2009 (Tron et al. 2013), although an analysis of satellite images measured only 0.6% loss of forest habitat across the species' range over the last three generations or 17 years (Tracewski et al. 2016).

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:50-249Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No
No. of individuals in largest subpopulation:95-99

Habitat and Ecology [top]

Habitat and Ecology:It inhabits a humid forest/maquis matrix, including small isolated forest patches, usually on ultrabasic soils, 100-850 m, historically in the hills to 1,000 m (Ekstrom et al. 2000), and has also been recorded in dry forests at Pouembout (S. Sirgouant verbally 1998, N. Barré in litt. 2003). Habitat modelling of an extensive series of recent surveys suggests that the species prefers altitudes of 600–900 m on ultramafic soil in high rainfall (>3000 mm rain per year) areas and in forest patches larger than 100 km2 and with high forest cover (Okahisa et al. 2016). It is an unobtrusive species seen singly or in pairs in the canopy or midstorey, feeding on invertebrates and nectar (Warner 1947, Ekstrom et al. 2000). Nests are built in open forests and are very poorly camouflaged, leaving them open to predation (Létocart 2006). Radio telemetry revealed that a pair occupied a territory of 100 ha (Létocart 2006). Birds appear to maintain the same territory and from year to year nests appear to be situated close together in the core of the territory. In the Parc de la Rivière Bleue the species breeds between July and December (Baudat-Franceschi 2013). 

Systems:Terrestrial
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):5.8
Movement patterns:Not a Migrant

Threats [top]

Major Threat(s): Forest loss and degradation caused by logging, nickel mining and fires is likely to be a threat (Ekstrom et al. 2000, 2002), potentially having had a considerable impact in the côté oubliée from where the species now appears to be absent (V. Chartenrauldt in litt. 2009). The apparent decline at Rivière Bleue must be caused by other factors; with the species apparently subjected to severe predation pressure by introduced rats Rattus spp.(Ekstrom et al. 2002, N. Barré in litt. 2003, Létocart 2006) and possibly cats Felis catus (R. Stirnemann in litt. 2012). No successful nests or juvenile birds were seen until 2004 at Rivière Bleue, suggesting that the limiting factor affects its breeding success (Y. Létocart in litt. 1999). However, in 2004 and 2005, two chicks fledged successfully and were tracked visually for a few days. Nesting areas were heavily poisoned for rat population control which may explain the nesting success but another nest, found in 2005, and also in an area where rats were controlled failed with the chick disappearing during the first week (Létocart 2006). Other possible nest predators include native endemic predators such as New Caledonian Crow (Corvus moneduloides), White-bellied Goshawk (Accipiter haplochrous), New Caledonian Giant Gecko (Rhacodactylus leachianus), Swamp Harrier (Circus approximans) and Peregrine Falcon (Falco peregrinus) (Baudat-Franceschi 2013); nests are poorly camouflaged and presumably easy to locate (Létocart 2006). One of the two chicks visually monitored after fledging was usually moving between trees on the forest floor, this could mean that the species is also vulnerable to cats, dogs and pigs (Létocart 2006). Grazing of understory vegetation by Rusa Deer (Cervus timorensis) may reduce habitat quality for the species (Baudat-Franceschi 2013). Forestry operations pose a threat as access roads allow the spread of invasive species, fire and hunters (Baudat-Franceschi 2013). Given the very small population size, hunting is also a potential threat. The species may be susceptible to avian malaria.

Conservation Actions [top]

Conservation Actions: Conservation Actions Underway
Hunting and capture is prohibited. The main known populations are found within protected areas: Parc Provincial Rivière Bleue, Réserve naturelle du Mont Kouakoué, Réserve naturelle de la Haute Pourina and Réserve botanique du Mont Panié (Baudat-Franceschi 2013). A breeding monitoring project conducted basic ecological research in the protected Parc Provincial Rivière Bleue from 2001 to 2005, including the radio-tracking of adults and video monitoring of nests (Y. Létocart in litt. 1999, Létocart 2006). Surveys were conducted in 2003-2006 by the IAC to establish the status of forest birds across New Caledonia (Chartendrault and Barré 2005, 2006). In 2010, the SCO conducted surveys in the Massif du Sud IBA (Angin 2011). There is ongoing conservation work around Mt Panié in the north (Tron et al. 2013).

Conservation Actions Proposed
The Crow Honeyeater Conservation Plan aims to gain a robust estimate of the total population, implement long-term population monitoring and study the threats and potential conservation actions. The plan highlights invasive species as the threat which requires most urgent attention. Rat populations should be managed in occupied territories and at known nest sites, cat populations should also be monitored in these areas. Deer and pig numbers should also be controlled. Further actions listed in order of priority are: to prevent further fragmentation of forest habitat, involve mining concessions in the development of a conservation strategy for the species, raise awareness of the threatened status of the species within the hunting community, and ensure that the species is included in management plans within protected areas (Baudat-Franceschi 2013). 


Citation: BirdLife International. 2016. Gymnomyza aubryana. The IUCN Red List of Threatened Species 2016: e.T22704320A93963198. . Downloaded on 24 March 2017.
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