Saxaul sparrow

The saxaul sparrow is one of the larger sparrows at and . Like all other sparrows, it flies swiftly and often at height. Distinctive markings, especially on its head, make the saxaul sparrow unlikely to be confused with any other bird. Its common call is a chirp, transcribed as , softer and more melodious than that of the house sparrow. It gives a flight call transcribed as twerp, and a song described by Russian naturalist V. N. Shnitnikov as "not loud, but pleasantly melodious with fairly diversified intonations". == Taxonomy ==

The saxaul sparrow was first described by English zoologist John Gould in a March 1872 instalment of The Birds of Asia, from a specimen collected near Kyzylorda, now in southern Kazakhstan, by Russian naturalist Nikolai Severtzov. Severtzov had been planning to describe the species as Passer ammodendri for several years and had been distributing specimens among other naturalists. When natural history dealer Charles Dode escaped from the Paris Commune in 1871 with some of his collection, Gould obtained specimens from a set of rare birds Dode exhibited to the Zoological Society of London. Severtzov did not describe the species until 1873, and some later writers preferred to attribute it to him, but Gould's description takes priority over Severtzov's. The saxaul sparrow's species name refers to its desert habitat, coming from the name of the Ammodendron or sand acacia tree, which is in turn derived from the Ancient Greek άμμος (, "sand") and δένδρον (, "tree"). The English name saxaul sparrow refers to the saxaul plant, with which it is closely associated. The saxaul sparrow usually is classified in the genus Passer with the house sparrow and around twenty other species, although a genus Ammopasser was created for the saxaul sparrow by Nikolai Zarudny in 1890. The saxaul sparrow's relationships within the genus Passer are unclear. However, because of its black throat feathering, it has usually been considered part of the "Palaearctic black-bibbed sparrow" group, related to the house sparrow. J. Denis Summers-Smith considered that the Palaearctic Passer sparrows evolved about 25,000 to 15,000 years ago, during the last glacial period. During this time, sparrows would have been isolated in ice-free refugia, such as a certain steppe region in Central Asia, where Summers-Smith suggested the saxaul sparrow evolved. Genetic and fossil evidence suggest a much earlier origin for the Passer species, perhaps in the Miocene and Pliocene, as suggested by Luis Allende and colleagues in their 2001 phylogenetic analysis of mitochondrial DNA. This analysis, based on a small sample of Passer species, suggested that the saxaul sparrow is sister to Passer griseus and that the two species together are sister to Passer melanurus. A 2021 molecular phylogenetic analysis with a larger sample of species found a clade of Afrotropical Passer species, which was sister to a clade of Palearctic and Oriental species (which includes the saxaul sparrow) that diverged from each other about 5.5 million years ago. Across its Central Asian distribution, the saxaul sparrow occurs in six probably disjunct areas, and is divided into at least three subspecies. ammodendri birds breed sporadically in parts of central Turkmenistan, Iran, and possibly Afghanistan, migrating to the south during the winter. The subspecies stoliczkae was named after Ferdinand Stoliczka in 1874 by Allan Octavian Hume, from specimens Stoliczka collected in Yarkand. This subspecies is separated from the other two subspecies by the Tian Shan mountains. It is found across a broad swath of China from Kashgar east to the far west of Inner Mongolia, through the areas around the Taklamakan Desert (but probably not in the inhospitable desert itself), and through the east of Xinjiang, northern Gansu, and the fringes of southern Mongolia. In the extreme west of the Gobi Desert a disjunct population separated from the other stoliczkae birds by the Gurvan Saikhan Uul mountains occurs, which is sometimes separated as a subspecies timidus. The subspecies nigricans, described by ornithologist L. S. Stepanyan in 1961, is found in northern Xinjiang's Manasi River valley. == Habitat ==

The saxaul sparrow is found in remote parts of Central Asia, where its distribution is believed to comprise six disjunct areas, though this is uncertain due to the scarcity of records. It is found in deserts, especially around rivers and oases. It is usually found around shrubs such as saxaul (Haloxylon), poplar (Populus), or tamarisk (Tamarix). Sometimes it occurs around settlements and grain fields, especially during the winter. == Behaviour ==

Little is known about the saxaul sparrow's behaviour due to its remote range. It is shy in many areas, and spends much time hidden in foliage, but breeding birds in Mongolia were reported to be "quite confiding". When not breeding, it is social, and can form flocks of up to fifty birds, sometimes associating with Eurasian tree, Spanish, and house sparrows. In some regions, it makes small local migrations. Towards the spring, saxaul sparrows form pairs within their flock, before dispersing in April. Nests are often built in tree cavities, where they are sometimes placed close together. Nests in man-made structures are increasingly common, as large trees in the saxaul sparrow's habitat are removed. In some clutches, one egg is noticeably paler than the others. Four eggs collected by Zarudny from Transcaspia had an average size of . Young that have left their nest remain nearby until well after their moult, before departing for winter flocks, followed later by the adults. == References ==