Justification of Red List Category
Although intensive conservation action has now reversed declines and resulted in a substantial population increase, the population size remains tiny, and the species therefore qualifies as Critically Endangered.
The known population in 2012 was 43-44 individuals (Blanvillain 2012), however the population size had increased to >50 individuals in 2014 (M. O'Brien and C. Blanvillain in litt. 2015). The number of mature individuals likely still remains within the band <50.
Since 2004, the species has shown signs of recovery, with new pairs becoming established in abandoned territories and recruitment of young birds in 2008 (Ghestemme in litt. 2012). The total population has increased slightly to 19 known individuals (40-45 estimated individuals) in 2006 (Gouni et al. 2007) and a known population of 40 individuals in 2011 (Ghestemme et al. 2011) and 43-44 in 2012 (Blanvillain 2012).
Pomarea nigra is endemic to Tahiti in the Society Islands, French Polynesia. It was apparently rare throughout the 20th century and, during the period 1986-1991, was noted in only four valleys (several pairs at each locality) out of 39 visited (Monnet et al. 1993). In September 1998, 27 birds (12 pairs) were located within these four lowland valleys. This figure has remained stable or perhaps increased slightly and in 2006 there were 12 territories occupied by 19 adult or subadult birds in accessible parts of the valleys, with new pairs even becoming established in abandoned territories, and the total population estimated at 40-45 individuals (P. Raust in litt. 2005, Gouni et al. 2007). The known population of mature birds numbered 35 individuals in 2010 (Anon 2010, Gouni et al. 2011), and 40 individuals (including 7 fledglings) in 2011 (Ghestemme et al. 2011). In 2012 there were 43-44 individuals including 38 territorial birds (25 in 2011), 25 territories (18 in 2011) and 12 pairs fledged nine young, a record since recovery began (Blanvillain 2012, Anon. 2013). Numbers have continued to increase with an estimated 20 breeding pairs in 2014 (M. O'Brien and C. Blanvillain in litt. 2015), fledging 12 young (LPO 2014).
It is only found between 80 m and 400 m in altitude, and the tree mara Neonauclea forsteri is a common feature of the four valleys where it survives (Thibault et al. 1999). Nesting sites are often situated at the bottom of valleys, close to permanent or temporary streams, with habitat dominated by alien plant species (Portier 2010). It is highly territorial, foraging both in the canopy and the undergrowth for insects (Pratt et al. 1987).
Its decline on Mt Mara`u might be related to the replacement of the high, dense forest by shrubs of the botanical pest Miconia calvescens, introduced in 1937, whose progression was partly facilitated by a hurricane in 1983 (J.-C. Thibault in litt. 1993). A decline in habitat quality is a likely threat elsewhere, as forest is largely composed of introduced invasive species, such as the African tulip tree (Spathodea campanulata), and usually confined to a narrow strip along the floor of steep basalt canyons (Gaze 1998). Predation by rats, particularly Black Rat (Rattus rattus), is probably the main threat (Blanvillain 2000, Thibault et al. 2002), and goat grazing is leading to habitat degradation in some areas (Ghestemme 2009). A three-year study showed that significantly more Red-vented Bulbul (Pycnonotus cafer) and Common Myna (Acridotheres tristis) were present in territories that experienced nest failure or early fledgling death (Blanvillain et al. 2002), while other potential predators include cats and Swamp Harrier (Circus approximans) (Ghestemme 2009). Common Myna has been implicated in the predation of eggs, and chicks while in the nest and probably following fledging. Red-vented Bulbul has been implicated in reducing chick survival by disrupting the reproduction of paired Monarchs, and competing for food and territories. Unnatural nest failures during 2008-2010 were related to mynas, although bulbuls are apparently responsible of the unique failure of 2011 (Ghestemme 2011, T. Ghestemme in litt. 2012). Tahiti Kingfisher (Todiramphus veneratus) is an aggressive competitor which has been observed driving several monarchs off their territory (Ghestemme 2009) and preventing colonisation of suitable sites by young monarchs (Ghestemme 2011). Concern is growing over the spread of Fire Ants (Wasmannia auropunctata) within species's territories (M. O'Brien and C. Blanvillain in litt. 2015).
Conservation and Research Actions Underway
In 1998, rat control around known nests (using poisoning and tree-banding) was initiated by the Société d'Ornithologie de Polynésie MANU (Blanvillain 2000). Rat control was more successful when conducted throughout the year and over the entire valley (Gouni 2006). However, when control was confined to monarch territories only, re-invasions occurred on a regular basis (Blanvillain et al. 2002). The number of areas controlled for rats has increased since 2008 (Ghestemme 2011). Rat control in Maruapo upper valley has improved in recent years with 28 bait stations set in 2011 (T. Ghestemme in litt. 2012) which has expanded into a network of 400 stations in 2014 (M. O'Brien and C. Blanvillain in litt. 2015). Some control of invasive Miconia and Spathodea is ongoing in accessible valleys (Raust 2010). In 2009-2011, 13 Tahiti Kingfishers were captured in the Papehue valley and moved to areas away from monarch populations with the aim of reducing competition. Following removal of the kingfishers, new colonisation of these areas by young monarchs was observed (T. Ghestemme in litt. 2012). An immature Tahiti Monarch found at a degraded site was translocated to a valley with suitable habitat and a low existing population (Ghestemme 2011).
An action plan has also been produced (Thibault et al. 1999), and the feasibility of translocation is being assessed: a recent feasibility study found that it would be possible to introduce the species to the island of Rimatara, based on the absence of Black Rat, Common Myna, Red-vented Bulbul and Swamp Harrier, and the availability of suitable nesting habitat (Portier 2010). Introduction of the first young birds to Rimatara was planned for 2013 (T. Ghestemme in litt. 2012). A recovery group, shared with Fatuhiva Monarch P. whitneyi, has been established to formulate a conservation strategy (T. Ghestemme in litt. 2010), and plans are underway to implement a site support group created in 2010. Between 2009 and 2011, 21 individuals have been colour-banded. A trapping campain resulted in the removal of 2,700 Common Myna and Red-vented Bulbul by 2012, and the same year there was no recorded predation by mynas (1-3 nest failures per year previously; Anon. 2013). Myna removal has continued in 2014 along the removal of Miconia, Triplaris and other invasive plants. Control of W. auropunctata has also begun. Education campaigns have helped raise awareness with 1,300 children and local people and children have grown more than 440 seedlings of plant species used by the monarch, over half of which have already been planted (M. O'Brien and C. Blanvillain in litt. 2015).
15 cm. Monochrome flycatcher. Adults entirely black with pale blue bill. Immatures rufous-cinnamon, paler below. Voice Call a sharp tick-tick-tick. Song a complex, flute-like melody.
Text account compilers
Bird, J., Calvert, R., Derhé, M., O'Brien, A., Pilgrim, J., Shutes, S., Stattersfield, A., Symes, A. & Wright, L
Ghestemme, T., Gouni, A., Millett, J., Raust, P. & Thibault, J.
BirdLife International (2018) Species factsheet: Pomarea nigra. Downloaded from http://www.birdlife.org on 21/07/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/07/2018.