While the news may have gone under the radar of anyone without an interest in bird watching, in 2016 scientists announced the discovery of a new avian species: Zoothera salimalii, the Himalayan Forest Thrush. Named in honour of the late Indian ornithologist Dr Salim Ali, whose extensive contributions to research have been invaluable to the base of scientific knowledge of birds, the species is found in China and Northern India. The Himalayan Forest Thrush is only the fourth new species to be discovered in India in the last 70 years.
In 1999 a team of sharp-eared international scientists, led by Swedish Professor Per Alström, noticed that the known species of Plain-backed Thrush (Zoothera mollissima) in the higher rugged elevations sounded quite different from their counterparts who lived in the forests. They determined that the former had a much harsher, somewhat raspy tone, while the latter, found below the tree line, were much more melodic and tuneful.
Discovering the Differences
Because the forest-dwelling thrush is notoriously elusive, it was, at first, difficult for scientists to learn whether there were in fact any physical differences between the two – as on the surface their plumage and anatomy are very similar. It wasn’t until several years of research, DNA analysis and painstaking comparison studies between the wild birds and specimens from 15 different museums that physical and genetic differences between the two were confirmed.
A Few Million Years of Separation
What scientists discovered from DNA analysis was that while the two different birds had come from the same ancestor, they had been breeding entirely separately for at least several million years. To put in it context, Professor Alström likened their genetic evolution and relationship to that of humans and chimpanzees.
The reasons for the split in breeding most likely occurred as an adaptation to surviving in their very different habitats – for example, the forest bird has shorter legs than the alpine bird, as longer legs are more of a physical benefit in open or mountainous habitats. Aside from the difference in leg length, the alpine species also has a longer tail.