Eastern Rock Nuthatch (Sitta tephronota) - HBW 13, p. 141

Taxonomy: Sitta tephronota Sharpe, 1872, Kokand, Fergana, east Uzbekistan.
Closely related to S. neumayer, the two together often considered an offshoot of “S. europaea group”, nest details suggesting particularly close relationship with S. cashmirensis. They probably became fully ecologically isolated from each other when geographically separated, present species adapting to continental conditions (with colder winters and hotter summers) that favoured a larger body and bill and S. neumayer to a less extreme Mediterranean climate. When coming into contact again, in S Iran, a process of what is termed “character displacement” selected for a bolder eyestripe and larger body size in present species; overlap zone in N Iran may be more recent, and the two species may not have diverged sufficiently to permit altitudinal coexistence. Race obscura sometimes treated as a separate species, but intergrades with dresseri in Iranian Azerbaijan and with nominate in NE & SE Iran, probably also with iranica in E Elburz Mts (N Iran). Birds of this species in upper Aras valley (NE Turkey) and in mountains of WC & SE Iran (Qom, Anarak massif and Yazd E to Jebal Barez; also S Sistan and Baluchistan) of uncertain racial identity, provisionally placed with obscura; likewise, birds in Khorasan area of NE Iran provisionally included in iranica. Four subspecies recognized.