A seventh species of Certhia treecreeper

On 30 May 2000, at the top of the table mountain plateau Wa Shan, Sichuan, China (29:38 N, 102:57 E), Marten Olsen and Yue-Hua Sun observed a treecreeper Certhia which immediately struck them as distinctive in size, plumage coloration and song. The bird was collected. Studies of skins and literature showed that this treecreeper belonged to a taxon that was described in 1995 as a subspecies of Eurasian Treecreeper, C familiaris tianquanensis (Li, G-Y 1995. A new subspecies of Certhia familiaris (Passeriformes: Certhiidae). Acta Zootaxonomica Sinica 20: 373-377. [In Chinese; English summary.]). Study of morphology, vocalizations and the cytochrome-b gene of the specimen collected on 30 May 2000 confirmed that this taxon should be considered as a separate species: Sichuan Treecreeper C tianquanensis (Martens, J, Eck, S & Sun, Y-H 2002. Certhia tianquanensis Li, a treecreeper with relict distribution in Sichuan, China. J Ornithol 143: 440-456). The species appears to be more closely related to Brown-throated Treecreeper C discolor than to Eurasian Treecreeper. It is differentiated by a long wing and tail, an extremely short bill and smoky-brown underparts, gradually becoming paler from the upper belly and breast towards the white throat and chin; the genetic difference of the specimen with Brown-throated Treecreeper was 8.8%, indicating that the taxon has been separated for a long time; and the voice is strikingly different from all six other Certhia species. The species probably occupies a very restricted range and has until now only been found at four localites in western Sichuan.
André J van Loon