This discussion was first published as part of the 2017 Red List update. At the time a decision regarding the status of several was pended, but to enable potential reassessment of these species as part of the 2018 Red List update this post remains open and the date of posting has been updated.
Luzon Water-redstart, Phoenicurus bicolor, is endemic to the island of Luzon, Philippines, where it occurs mainly in the Cordillera Central but also Sierra Madre mountains. It is restricted in its habitat to undisturbed, clear, fast-flowing waters which makes it particularly threatened by pollution of these watercourses by mining activities (D. Allen in litt. 2007, 2012). Local farmers are also using an increasing amount of agro-chemicals which could be affecting water quality. The forest adjacent to these streams is also threatened by habitat clearance, with a large proportion of Benguet province under intense cultivation, although some areas with poor/no road connectivity may persist (D. Allen in litt. 2007). As a result of this the population is considered to be undergoing a rapid decline, which, combined with the species being considered to occur at only a limited number of locations, led to the species being considered as Vulnerable under criteria A2c+3c+4c; D2.
A re-assessment of available information suggests that the species may warrant uplisting though. The population was estimated at 2,500-9,999 individuals based on an assessment of population density estimates of congeners or closely related species of a similar size, known records, range size, descriptions of abundance and assuming only a proportion of its range is occupied (see BirdLife International 2017). This roughly equates to 1,667-6,666 mature individuals, rounded to 1,500-7,000 mature individuals.
There have been records from Dalton Pass between August and December suggesting that after the breeding-season some individuals may make movements (see BirdLife International 2017), and so the species may be best considered to be one subpopulation. There have also been two recently discovered records from the 1960s from Mindoro, which could further back up the suggestion that this species may undergo some movements. However, it possibly could also represent an unknown population on this island (if it still persists there), but if this were the case, the proportion of the global population found there is likely to be very small.
To qualify as Endangered under criterion C2a(ii) a species must have a population size of <2,500 mature individuals, with 95-100% of the population in one sub-population. Given that the lower boundary of the population size range is below this figure then the species may be said to meet the threshold population size. The species may also meet the population structure criterion because it may be considered to consist of one sub-population (see above), and even if reports from Mindoro do represent a separate sub-population the proportion of the global population found there is likely tiny (<5%). Therefore, the species may be said to meet the threshold for Endangered under criterion C2a(ii), and it would warrant listing as such.
We welcome any comments or further information regarding this proposed uplisting.
BirdLife International. 2017. Species factsheet: Phoenicurus bicolor. Downloaded from http://www.birdlife.org on 07/04/2017.