Justification of Red List Category
This species has suffered a continuing decline in the one remaining subpopulation, which is thought to now number c.30 pairs, and it is consequently classified as Critically Endangered. Two thirds of remaining individuals are male, and this ratio has worsened owing to unknown reasons, although introduced predators are implicated. Conservation work appears to have begun to address the gender imbalance but further intervention is required to combat current threats and reverse the continuing decline.
The population perhaps numbered as few as 25 breeding pairs, or 50 mature individuals, in 2007 (T. Ghestemme in litt. 2007); and 31 pairs and 28 non-breeding males in 2011 (SEOR, 2012), and 33 pairs in 2013 (Fouillot et al. 2013).
Two thirds of the population are now males, and this ratio has worsened over time, indicating a continuing decline in the number of mature individuals, estimated at a rate of 1-19% over ten years. However, data tentatively suggests population may be stabilising (over 1 generation) at a very low population size.
Coracina newtoni is endemic to Réunion (to France), and restricted to the north-west (Plaine d'Affouches, Plaine des Chicots, eastern part of the Cirque de Dos d’Ane, the Roche-Ecrite massif and massif de la Grande Montagne) (Thiollay and Probst 1999, Le Corre and Safford 2001, Fouillot and Salamolard 2013). The population was estimated at 120 pairs after surveys in 1991, suggesting that numbers had been stable since 1974. However, the population was estimated at 100 singing males in the 2003-2004 breeding season, indicating that the species had declined (Ghestemme and Salamolard 2007). In 2003-2004, surveys revealed a skewed sex ratio, with 27% of males unpaired, and poor reproductive success, with only a third of females producing young (Ghestemme and Salamolard 2007). In 2004-2005, the proportion of surveyed males without mates had risen to 48%, with 30% of females producing young (Ghestemme and Salamolard 2007), and there was evidence that the species had declined in the east of its range (Ghestemme 2005a); the proportion of surveyed males without mates increased further to 57% in 2005-2006 (T. Ghestemme in litt. 2006), and 64% in 2006-2007 (T. Ghestemme in litt. 2007, 2008). Males are thought to now outnumber females by two to one, and in 2007 there were thought to be as few as 25 breeding pairs, but there are early indications that predator control is proving successful, with an increase in female survival and improved breeding success (T. Ghestemme in litt. 2007, 2008), and a sex ratio in 2010 of 1.88:1 in favour of males (SEOR 2012). In 2011/2012 31 breeding pairs were observed, of which 11 were successful, raising a total of 18 young (SEOR 2012).
It has been conjectured that it primarily occupied lowland forest in the past (Thiollay and Probst 1999). The species now occurs between 1,000 and 1,800 m (Salamolard and Ghestemme 2004), and is strictly associated with closed-canopy natural forest, occurring in mixed evergreen subtropical forest that also often includes areas of heath Philippia montana and tamarin (Acacia heterophylla) (Morgan and Kershaw 1990, Probst 1996, Thiollay and Probst 1999). Japanese red cedar (Cryptomeria japonica) plantations are only rarely visited and seasonal records in the heath forest are attributed to post-breeding dispersal. It is chiefly insectivorous but also eats the fruits of some native trees (Thiollay and Probst 1999). Breeding occurs between September and February, and it has an incubation period of 15-17 days and a fledging period of 20-23 days (Salamolard and Ghestemme 2004).
Nest predation by black rats (Rattus rattus), and to a lesser extent brown rats (R. norvegicus) and feral cats appears to be the primary reason for poor reproductive success; and it is possible that this explains the skewed sex ratio (Thiollay and Probst 1999, M. Le Corre in litt. 2000, Salamolard and Ghestemme 2004, B. Devuax per Poudroux undated). In recent years the spread of Red-whiskered Bulbul (Pycnonotus jocosus), has caused concern as it it thought it competes for food, breeding areas and may also predate cuckoo-shrike eggs (Krumenacker 2014). The dropping of litter in the Roche Ecrite Nature Reserve by visitors inadvertedly supports the proliferation of the rat population (Ghestemme 2005b, Poudroux undated).
Other major threats include poaching for trade and for food (Thiollay and Probst 1999, M. Le Corre in litt. 2000, Ghestemme and Salamolard 2007), and disease (Ghestemme and Salamolard 2007). The species is also threatened by disturbance from recreational activities, fire, cyclones, invasive alien vegetation, potential competition with other bird species and habitat degradation caused by Rusa Deer (Cervus timorensis rusa) (Salamolard and Ghestemme 2004, Ghestemme and Salamolard 2007). The population may be limited by habitat quality and food resources (Ghestemme and Salamolard 2007). In addition, intrinsic factors such as limited dispersal and low genetic variability may affect the population (Ghestemme and Salamolard 2007); yet while the population shows low genetic diversity, there is no evidence to show it is significantly inbred (Salmona et al. 2012). Since the remaining population seems unable to colonise new areas, habitat changes, such as degradation by the invasion of exotic vegetation or forest fires, could be catastrophic (Probst 1996, Thiollay and Probst 1999). Construction of roads and hotels for tourism were thought to be potential problems (V. Bretagnolle and C. Attié in litt. 1993) but there are currently no such projects within the breeding range of the species nor in its vicinity (M. Le Corre in litt. 2000). Nests are also vulnerable to adverse weather conditions (Barré et al. 1996, Thiollay and Probst 1999), and, having a montane distribution that is close to the maximum altitude within its range, this species is potentially susceptible to climate change (BirdLife International unpublished data).
Conservation and Research Actions Underway
In 1999, the 36 km2 reserve of Roche Ecrite was established, incorporating 95% of the current range of C. newtoni (Salamolard and Ghestemme 2004). Habitat management involves a logging ban, control of exotic plants, fire breaks, better control of hunting, curbing of tourism (Thiollay and Probst 1999), and action to reduce deer numbers (Le Corre and Safford 2001). Maturing plantations of Cryptomeria are being progressively replaced with native Acacia (Thiollay and Probst 1999). In 2006, an awareness campaign to reduce littering and promote recycling had been planned (T. Ghestemme in litt. 2006). In 2004, a species action plan was published with the aim of reversing the trend towards extinction by increasing the numbers of females in the population, eventually doubling the number of females over the course of 10 years and achieving a viable population of 125 pairs (Salamolard and Ghestemme 2004). Experimental rat and cat control was initiated in the Roche Ecrite reserve prior to the 2005-2006 breeding season (Ghestemme 2005b), through the setting of poisoned baits, accompanied by the trapping of rats and cats to monitor their populations (T. Ghestemme in litt. 2006, Fouillot et al. 2013). In the 2005-2006 breeding season, four out of five pairs in sites with predator control raised young, compared with two out of six pairs in uncontrolled sites (T. Ghestemme in litt. 2006). The control programme was carried out at 11 nest sites during the 2006-2007 breeding season; however three females disappeared, and six out of the eight remaining pairs produced young (T. Ghestemme in litt. 2007, 2008). In 2007, the total number of young fledged increased to 22, with a breeding success of 91% at sites with predator control (compared to around 30% at those without) (T. Ghestemme in litt. 2007, 2008). In 2010, predator control measures by Société d'Etudes Ornithologiques de La Réunion (SEOR), with some support from the BirdLife Preventing Extinctions Programme, were on-going (D. Fouillot in litt. 2010), and rats have been cleared from 700ha due to the collaboration between SEOR, Reunion National Park and French National Forestry Agency (Life + Cap Dom 2015). A revised species action plan for 2012-2016 was being finalised in 2012 (A. Cheke in litt. 2012).
22 cm. Greyish arboreal bird. Male overall dark grey with paler underparts, especially on flanks and vent. Dark face imparts masked effect. Tail tipped white. Female dark brown above with very obvious, narrow white eyebrow-stripe and pale, finely barred underparts. Voice Shrill and clear whistled tui tui tui. Female gives harsh shrek alarm note. Hints Quiet, inconspicuous bird, particularly when feeding, occurring either singly or in pairs.
Text account compilers
Ekstrom, J., Pilgrim, J., Shutes, S., Stattersfield, A., Symes, A., Taylor, J., Warren, B., Wright, L & Westrip, J.
Attié, C., Bretagnolle, V., Ghestemme, T., Le Corre, M., Cheke, A. & Safford, R.
BirdLife International (2020) Species factsheet: Lalage newtoni. Downloaded from http://www.birdlife.org on 31/05/2020. Recommended citation for factsheets for more than one species: BirdLife International (2020) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/05/2020.