Coal Tit (Periparus ater) - HBW 12, p. 722

Taxonomy: Parus ater Linnaeus, 1758, Sweden.
Until recently present genus normally subsumed into a broad Parus, and many authors still prefer that treatment. Forms a superspecies with P. melanolophus, and the two regularly hybridize in W Nepal; sometimes considered conspecific. Known to have hybridized also with Poecile montanus, Lophophanes cristatus and Parus major. Geographical variation well marked but complicated by high degree of local and individual variation within populations; furthermore, races intergrade in parts of range; ongoing genetic research suggests presence of a series of regional clusters across range. Additional proposed races are pinicolus (described from Scotland), synonymized with britannicus;and abietum (from W & C mainland Europe), rossosibiricus (C Russia from Moscow E to about L Baikal) and amurensis (Amurland, Ussuriland, Sakhalin), all merged with nominate. Recently described eckodedicatus (Gansu, Sichuan, Shaanxi, N Yunnan) morphologically almost identical to aemodius; probably merits separation, on basis of genetic differences. Twenty-one subspecies currently recognized.