Siberian chiffchaff to be a full species due to its distinctive plumage and vocalisations, being similar to "P. s. sindianus" in these respects. Common chiffchaffs (of the nominate race) and Siberian chiffchaffs do not recognize each other's songs. Pending resolution of the status of the form "fulvescens", which is found where the ranges of common chiffchaff (of the race "abietinus") and Siberian chiffchaff connect and may or may not be a hybrid between these, "tristis" is maintained in "P. collybita" by most checklists. Siberian chiffchaff Siberian chiffchaff ("Phylloscopus (collybita) tristis") is a leaf-warbler which is usually considered a subspecies of the common
Canary Islands chiffchaff and a longer tail. Its underparts have a brownish-buff tone, especially on the flanks and breast, and the upperparts are darker brown than the common chiffchaff. Many calls are similar to the common chiffchaff but the song lacks the metronomic quality of that species and is harsher, shorter and more varied and with a faster delivery. The Canary Islands chiffchaff occurs in most habitats from coastal gardens to high altitude vegetation but is absent from semi-desert scrub at lower altitudes. In the breeding period, January to June, the Canary Islands chiffchaff is territorial and is found singly or in pairs,