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 1-49.
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 from 19 known individuals (40-45 estimated individuals) in 2006 (Gouni et al. 2007) to a known population of 40 individuals in 2011 (Ghestemme et al. 2011), 43-44 in 2012 (Blanvillain 2012) and 53 in 2015 (Blanvillain et al. 2017).
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 and Zyman 2011), and 40 individuals (including seven 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). In 2015, 52 individuals (but only 13 breeding pairs) were recorded (Blanvillain et al. 2017).
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 have been 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). Trapping programmes of introduced birds have been performed since 2000, which has led to the elimination of the Indian Mynah and to and increase in nesting success of the Tahiti Monarch (Blanvillan in litt. 2016). Regular 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 a 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). 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 campaign 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 with 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).
Conservation and Research Actions Proposed
Regularly monitor known territories in the three valleys, including searching for nests, searching for birds in previously known locations and surveying possible new areas (Thibault et al. 1999). Continue rat control throughout the year (SPREP 1999, Thibault et al. 1999, Blanvillain 2000, Blanvillain et al. 2017). Conduct experiments to improve the quality of the habitat in a couple of valleys by encouraging the growth of young mara trees and removing African tulip trees (Thibault et al. 1999). Control introduced birds (SPREP 1999, Thibault et al. 1999, Blanvillain 2000). Animate the Monarch Recovery Group by submitting the synthesis on different aspects of Tahiti monarch conservation including the translocation procedure. Develop the Operational Plan for the introduction of Monarch to Rimatara island. Locate and survey more intensively birds selected for being transferred on Rimatara.
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
Symes, A., Wright, L, Hermes, C., Bird, J., Derhé, M., O'Brien, A., Calvert, R., Pilgrim, J., Shutes, S., Stattersfield, A.
Gouni, A., Thibault, J., Raust, P., Millett, J., Ghestemme, T.
BirdLife International (2020) Species factsheet: Pomarea nigra. Downloaded from http://www.birdlife.org on 11/08/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 11/08/2020.