stripe that does not meet the mantle. The male has a grey crown and nape and a rufous lower back and rump. The female has a darker and greyer crown and cheek than the female house sparrow and the shoulder is darker chestnut. The female Dead Sea sparrow of the subspecies Passer moabiticus yattii is also similar to the female Sind sparrow, but has yellow tinges on the underparts and sometimes on parts of the head. The bill is black on the breeding male and pale brown on the non-breeding male and female. With a culmen length of , the Sind sparrow is slightly smaller-billed than the house sparrow. The Sind sparrow's chirping chup call is softer, less strident, and higher pitched than that of the house sparrow, and is easily distinguished. The song of breeding males includes chirrups interspersed with grating t-r-r-rt notes and short warbles or whistles. Taxonomy The Sind sparrow was first formally described by Edward Blyth, from a specimen collected by Alexander Burnes at Bahawalpur in around 1840. Blyth's description was published in an issue of the Journal of the Asiatic Society of Bengal which, although dated 1844, was published only in 1845. The sparrow was not recorded until 36 years later, despite the efforts of noted ornithologists Allan Octavian Hume in Sindh and William Thomas Blanford in eastern Iran. This was probably because of its general similarity to the house sparrow, though additionally, Blyth's description of the species incorrectly described its rump feathers as maroon, and a description by Thomas C. Jerdon contained similar errors. Commenting on his unsuccessful search, Hume wrote that the hundreds of house sparrows he killed in pursuit of the Sind sparrow "ought to form a heavy load" on Blyth's conscience, and that if the Sind sparrow existed "it would be only decent for it ... to put on an appearance with as little delay as possible". Hume doubted its distinction, as did other ornithologists. The Sind sparrow was rediscovered by Scrope Berdmore Doig in 1880, in the Eastern Nara district. Ernst Hartert considered it a subspecies of the house sparrow, Passer domesticus pyrrhonotus, in his Die Vögel der paläarktishen Fauna, but Doig and Claud Ticehurst both found that the two species bred in the same areas without interbreeding. The specific epithet of the Sind sparrow, pyrrhonotus, comes from the Greek purrhos ("flame-coloured"), and -nōtos ("-backed"). E. C. Stuart Baker suggested