Taxonomy
Most authorities retain Cyanistes as a subgenus of Parus, but the American Ornithologists' Union treats Cyanistes as a distinct genus. This is supported by mtDNA cytochrome b sequence analysis which suggests that Cyanistes in not only distinct, but not close to other tits (Gill et al., 2005).
The Azure Tit frequently hybridizes with the Blue Tit in western Russia; the resulting birds are called "Pleske's Tits" (Cyanistes × pleskei) and were once considered a distinct species.
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