Dusky Crag Martin - Taxonomy

Taxonomy

The Dusky Crag Martin was formally described by in 1832 as Hirundo concolor by British soldier and ornithologist William Henry Sykes. It was moved to the new genus Ptyonoprogne by German ornithologist Heinrich Gustav Reichenbach in 1850. Its nearest relatives are the thrre other members of the genus, the Rock Martin P. fuligula, the Pale Crag Martin, P. obsoleta, and the Eurasian Crag Martin P. rupestris. The genus name is derived from the Greek ptuon (φτυον), "a fan", referring to the shape of the opened tail, and Procne (Πρόκνη), a mythological girl who was turned into a swallow. The specific concolor is from Latin, con "together", and color "colour" and refers to the bird's uniform colouration.

The four Ptyonoprogne species are members of the swallow family of birds, and are classed as members of the Hirundininae subfamily which comprises all swallows and martins except the very distinctive river martins. DNA studies suggest that there are three major groupings within the Hirundininae, broadly correlating with the type of nest built. The groups are the "core martins" including burrowing species like the Sand Martin, the "nest-adopters", which are birds like the Tree Swallow that utilise natural cavities, and the "mud nest builders". The Ptyonoprogne species construct an open mud nest and therefore belong to the latter group; Hirundo species also build open nests, Delichon house martins have a closed nest, and the Cecropis and Petrochelidon swallows have retort-like closed nests with an entrance tunnel.

The genus Ptyonoprogne is closely related to the larger swallow genus Hirundo into which it is often subsumed, but a DNA analysis showed that an enlarged Hirundo genus should contain all the mud-builder genera, including the Delichon house martins, a practice which few authorities follow. Although the nests of the Ptyonoprogne crag martins resembles those of typical Hirundo species like the Barn Swallow, the research showed that if Delichon, Cecropis and Petrochelidon are split from Hirundo, Ptyonoprogne should be also considered as a separate genus.

In Pakistan, the breeding range of Dusky Crag Martin overlaps that of the subspecies P. f. peloplasta of Pale Crag Martin, but that species breeds much higher in the mountains. This altitudinal separation means that it is not known whether the two closely related martins could hybridise, which would cast doubts as to whether they were distinct species. Dusky Crag Martins from Burma and Thailand have been described as a separate darker subspecies, P. c. sintaungensis (originally Krimnochelidon concolor sintaungensis, Baker, 1832), but it is not clear that the difference is greater than that between individual martins of the nominate subspecies.