New species of thrush described in India and China

A new species of bird has been described in north-eastern India and adjacent parts of China by a team of scientists from Sweden, China, the US, India and Russia, headed by Professor Per Alström, Uppsala University and the Swedish University of Agricultural Science, SLU.

The bird has been named Himalayan Forest Thrush (Zoothera salimalii). The scientific name honours the great Indian ornithologist Dr Sálim Ali (1896–1987), in recognition of his huge contributions to the development of Indian ornithology and nature conservation.

Himalayan Forest Thrush was first discovered when it was realised that what was considered a single species, Plain-backed Thrush (Zoothera mollissima), was in fact two different species in north-eastern India.

Himalayan Forest Thrush (Photo: Craig Belsford)

What first caught the attention of the scientists was the fact that 'Plain-backed Thrushes' in the coniferous and mixed forest had a rather musical song. This was in contrast to individuals found on bare rocky ground above the treeline in the same area, as they had a much harsher, scratchier, more unmusical song.

Studies of museum specimens in several countries revealed consistent differences in plumage and structure between birds that could be assigned to either of these two species. It was confirmed that the species breeding in the forests of the eastern Himalayas had no name.

It was suggested that the high-elevation Plain-backed Thrush be called 'Alpine Thrush' instead, while retaining the scientific name of the 'original' species, Zoothera mollissima, in accordance with international nomenclatural rules.

Himalayan Forest Thrush (Photo: Per Alström)

Further analyses of plumage, structure, song, DNA and ecology from throughout the range of Plain-backed Thrush revealed that a third species was present in central China. This was already known, but was treated as a subspecies of Plain-backed Thrush. The scientists called it Sichuan Forest Thrush, the song of which was found to be even more musical than the song of Himalayan Forest Thrush.

DNA analyses suggested that these three species have been genetically separated for several million years. Genetic data from three old museum specimens indicated the presence of yet another unnamed species in China; further studies are required to confirm this.

Himalayan Forest Thrush is locally common. It has been overlooked until now because of its close similarity in appearance to the Alpine Thrush, and is only the fourth new bird species described in India since the country achieved its independence (1947).