Justification of Red List Category
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population size has not been quantified. The species is variously described as uncommon to fairly common across much of its range (Clement and Hathway 2000). In Europe, the breeding population is estimated to number 25,000-100,000 breeding pairs, equating to 75,000-300,000 individuals (BirdLife International 2004), but Europe forms <5% of the global range.
The population is suspected to be in decline owing to ongoing habitat destruction and degradation, although it is increasing in Europe (BirdLife International 2015).
This species predominantly breeds across Siberia from the southern Urals in Russia, east to north Mongolia and the Sea of Okhotsk, Amurland and Sakhalin, south to the Kurils, Japan and South Korea. This population is strongly migratory and winters south to northern south-east Asia, north and west Philippines, eastern and southern China, Chinese Taiwan and southern Japan. In addition there are two disjunct populations: "Sri Lanka Thrush" (previously considered a separate species) in the hills of south west Sri Lanka; and "Horsfield's Thrush" in Sumatra, Java and Bali, Indonesia. Birds on Iriomote-jima in the southern Ryukyu Islands and Taiwan, China are of uncertain taxonomic status.
In Russia, the nominate subspecies of White's Thrush breeds in dark coniferous and mixed forests of the southern boreal zone and dark taiga zone, typically in spruce (Picea) forests along river valleys, wooded steppe, mixed or broadleaf stands on ridges and slopes, open woodland with larch (Larix), birch (Betula) and aspen (Populus), often in headwater areas. Subspecies toratugumi breeds in montane and submontane forests in Korea and in Japan it occupies damp deciduous or mixed forest with dense undergrowth, mainly at 500–1,600 m in central Honshu or 0–800 m in Hokkaido. The nominate subspecies winters in broadleaf evergreen forest, as well as selectively logged and montane forest, bamboo groves and copses at all elevations. It also occurs in urban parks, open grassy areas such as lawns, picnic areas and golf courses adjacent to tree cover. In Japan, White's Thrush occurs in less dense cover in winter than when breeding. On its non-breeding grounds in the Philippines, the species prefers higher slopes, but can be found from sea-level to 1,000 m. Subspecies horsfieldi is usually found in montane and rhododendron forest at 920–2,800 m on Lombok and at 2,000–3,000 m in Sumatra. On Sumbawa, horsfieldi occurs in open casuarina forest with an understorey of giant nettles, ferns and shrubs, generally at 1,700 m (del Hoyo et al. 2016).
The species is threatened by ongoing deforestation and forest degradation.
Conservation Actions Underway
No targeted conservation actions are known for this species.
Conservation Actions Proposed
Monitor the species population and the rate of decline. Monitor habitat loss and other threats to the species.
Text account compilers
Everest, J., Martin, R., Pilgrim, J., Butchart, S., Ekstrom, J., Elliott, N., Westrip, J., Benstead, P.
BirdLife International (2021) Species factsheet: Zoothera aurea. Downloaded from http://www.birdlife.org on 19/10/2021. Recommended citation for factsheets for more than one species: BirdLife International (2021) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2021.