Justification of Red List Category
This species qualifies as Endangered because it has a very small range, being known from just two mountains, where on-going forest destruction is reducing the extent, area and quality of habitat, and inevitably leading to a decline in numbers. It appears to be exceedingly rare on one of the mountains and, if there are no further records in the near future, it should be considered confined to one location and may require uplisting to Critically Endangered.
The population is estimated to number 1,000-2,499 individuals based on an assessment of known records, descriptions of abundance and range size. This is consistent with recorded population density estimates for congeners or close relatives with a similar body size, and the fact that only a proportion of the estimated Extent of Occurrence is likely to be occupied. This estimate is equivalent to 667-1,666 mature individuals, rounded here to 600-1,700 mature individuals.
Habitat destruction within its tiny range is thought to be on-going, suggesting that moderately rapid and continuing population declines are likely to be occurring.
Stachyris nigrorum is endemic to Negros in the Philippines, where it is known from the vicinity of Mt Talinis in the south and from Mt Canlaon in the north (Collar et al. 1999). It was also recently sighted at Mt Hapono-haponon in Mantikil, Siaton (A. Bucol in litt. 2007). It is common around Mt Talinis, where surveys in 1991 recorded 76 individuals in a day, making it the second most frequently recorded species. However, it is likely to be declining within this very restricted range. There is only one (recent) record from Mt Canlaon, despite considerable subsequent fieldwork there, casting doubt over the importance of this site to the species.
It inhabits montane forest between 950 and 1,600 m, chiefly occurring between 1,050 and 1,400 m, generally favouring the lower storey. It seems to tolerate degraded habitats, having been recorded in recently degraded forest, secondary forest and dense bushes at the forest edge and in forest opened up for agriculture. However, it appears to be limited to areas with some remaining forest cover (A. Bucol in litt. 2007).
In 1988, it was estimated that a mere 4% of Negros remained forested. Deforestation, owing to agricultural encroachment and logging activities, has reached 1,250 m on Mt Talinis, higher than any other site on Negros. In 1993, a large proportion of the forest was protected by a single guard who, in response to threats from slash-and-burn farmers, was confining his patrol work to the road up the mountain.
Conservation Actions Underway
The Mt Talinis/Twin Lakes area has been proposed for conservation funding. This area includes c.40 km2 of high-altitude forest afforded nominal protection through the Negros Geothermal Reservation. Environmental awareness campaigns have been conducted near Mt Talinis itself. The Mt Canlaon Natural Park may afford some protection if the species persists there.
c.13 cm. Small, olive-brown and whitish babbler with moderately long, dark grey bill. Warm olive-brown upperparts, whitish underparts with relatively broad, contrasting dark streaking on flanks, ventral region suffused yellowish. Whitish eye-ring and conspicuous black mask. Similar spp. Possibly confusable with other small passerines with streaked underparts (e.g. Muscicapa flycatchers), but distinguishable by combination of behaviour and dark mask. Voice Rather thin, high-pitched contact call notes consisting of tsip-tsip-tsip, often in trills. Hints Often encountered in groups, including mixed-species foraging flocks.
Text account compilers
Benstead, P., Gilroy, J., Taylor, J.
BirdLife International (2019) Species factsheet: Zosterornis nigrorum. Downloaded from http://www.birdlife.org on 16/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 16/10/2019.