Chestnut Sparrow - Taxonomy

Taxonomy

This species was first described in 1880, by Gustav Hartlaub in the Journal für Ornithologie, as Sorella Emini Bey. Hartlaub gave it the specific name Emini Bey in honour of the explorer Emin Pasha, who collected the type specimen in modern South Sudan or Uganda near Lado, and it is occasionally given the eponymous common name Emin Bey's Sparrow. Hartlaub's unusual spelling of its specific epithet as two words led some to spell the name emini or emini-bey. No subspecies are recognised, but one was described by British ornithologist George L. G. Van Someren in 1922 from Archers Post in central Kenya, as Sorella eminibey guasso.

Hartlaub considered the Chestnut Sparrow's colouration and morphology to be distinct enough to allocate it to its own monotypic genus, Sorella. Although several authors have followed Hartlaub's treatment, it is usually been placed in the genus Passer. It is very similar to the two golden sparrows, from which it may have once been only clinally different. The male Arabian Golden Sparrow is almost entirely gold-coloured, the male Chestnut Sparrow is mostly chestnut, and the male Sudan Golden Sparrow is intermediate. British ornithologist Richard Meinertzhagen considered these three species to be conspecific; however, the range of the Sudan Golden Sparrow overlaps with that of the Chestnut Sparrow without any known interbreeding in a small area of Sudan. These species are similar in their behaviour, which is adapted to the unpredictable conditions of their arid habitat. In particular, they and the Dead Sea Sparrow share a courtship display in which males quiver their wings above their body. This intense display is probably an adaptation to nesting in a clump of trees surrounded by similar habitat, where such an intense display may serve important purposes in keeping a colony together.

The Chestnut and golden sparrows have been seen as highly primitive among the genus Passer, only distantly related to the House Sparrow and the related "Palaearctic black-bibbed sparrows". In recognition of this they are sometimes placed in a separate genus or subgenus Auripasser. The courtship display of the Dead Sea Sparrow was thought to have evolved separately in a similar environment from that of these species, in an example of convergent evolution. However, studies of sparrow mitochondrial DNA indicate that the Chestnut and golden sparrows are either derived from or are the closest relatives of the Palaearctic black-bibbed sparrows.