Researchers at the Chinese Academy of Sciences in Beijing and Uppsala University, Sweden, have put together all known information about the endangered Rufous-headed Robin in a new paper, published in Ibis.
There have been very few observations of this, one of the world's rarest and least-known birds, since it was first discovered in 1905. Despite this, the researchers suggest that its distribution might be larger than previously thought.
Professor Per Alström explained: "We have tried to estimate its potential distribution to find areas where it might occur but where it has not yet been observed. Since most of the potential new areas are in poorly accessible mountain ranges, we are hopeful that it has a larger distribution, and hence that it is less threatened than presently believed."
Rufous-headed Robin is related to the familiar Common and Thrush Nightingales. Like these it has a richly beautiful song, but (unlike the nightingales) male and females differ in plumage, the male sporting a particularly striking plumage.
Singing male Rufous-headed Robin, Jiuzhaigou, Sichuan, China, May 2013 (Photo: Pete Morris)
In the study, the researchers have summarised all known observations of Rufous-headed Robin since it was first discovered in the Shaanxi Province of central China in summer 1905. The second observation was not made until March 1963, in Malaysia.
In June 1985, three singing males were discovered at one site in the Sichuan Province in central China. The species has only been observed at this site and in a neighbouring nature reserve over the past 25 years, with a maximum of eight individuals in a year. It has been seen just twice in the non-breeding season in South-East Asia. No observations were made in 2016, despite searches at the two classic sites.
The potential distribution was estimated based on the species' known habitat preferences, and the researchers concluded that it might be more widespread than presently appreciated. Many of those areas have been poorly surveyed, so there is still hope that some unknown populations might be discovered.
The reasons as to why Rufous-headed Robin is so rare are unknown. The researchers analysed DNA from one individual and concluded that its closest relative is Rufous-tailed Robin, which breeds in Siberia and north-east China, whereas it is more distantly related to the two European nightingales. Analysis of the song found it most reminiscent of the distantly related Ryukyu Robin of Japan; this the result of parallel evolution, and accordingly is not due to common ancestry.
Zhao M, Alström P, Hu R, Zhao C, Hao Y, Lei F & Qu Y. 2016. Phylogenetic relationships, song and distribution of the endangered Rufous-headed Robin Larvivora ruficeps. Ibis. DOI: 10.1111/ibi.12426