Sichuan Bush Warbler

The Sichuan bush warbler lives primarily in the thick brush and on tea plantations in five mountainous provinces of central China. It is a relatively small bird with a weight of 10 grams and an average length of 13 cm. Unlike its congener the russet bush warbler, which is found in the same mountains and also in the Himalayas, Vietnam, the Philippines, and Indonesia, the Sichuan bush warbler prefers elevations below 7,500 feet. The two species shared a common ancestor about 850,000 years ago. They are distinguished by plumage and sonogram terminology – their songs. Locustella chengi emits a long buzz, followed by a shorter click, often repeated in series, and the song is in a lower frequency than that of its genetic cousin.

Source: Wikipedia