Chestnut sparrow
| Chestnut Sparrow | |
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| Male in breeding plumage in Kenya | |
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| Species: | P. eminibey
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| Binomial name | |
| Passer eminibey (Hartlaub, 1880)
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The Chestnut Sparrow (Passer eminibey) is a species of passerine bird in the sparrow family Passeridae. It is the smallest member of the genus Passer, at about Template:Cm to in long. The breeding male has deep chestnut plumage and the female and juvenile are duller in appearance. Like its closest relatives, the Arabian Golden Sparrow and the Sudan Golden Sparrow, it is gregarious, and is found in arid areas. It ranges through the east of Africa from Darfur to Tanzania in dry savanna, human habitation, and papyrus swamps. Adults and juveniles both feed mostly on grass seeds, and fly in flocks, often with other species of bird, to find food. It nests in trees, building its own domed nests, and also usurping the more elaborate nests of weavers.
Description
Like the other members of the sparrow family, the Chestnut Sparrow is a small, chunky songbird with a thick bill suited for its diet of seeds. At 10.5 to 11.5 cm (4.1–4.5 in) in length,[2] it is the smallest member of the genus Passer.[3] It weighs between 12 grams (0.42 oz) and 17 grams (0.60 oz).[2] The plumage of the breeding male is mostly a deep shade of chestnut in colour with black colouration on the face, wings, and tail. The chestnut colour is used descriptively in the common name. The breeding male is not easily confused with any other birds except the Chestnut Weaver, which is substantially larger and has white on its wings. The breeding male's legs and feet are pale horn.[4] The non-breeding male Chestnut Sparrow has white flecking on the upperparts, and loses much of the chestnut from the underparts plumage, which becomes buff or whitish with chestnut crescent markings. The non-breeding male's bill fades to a dusky-tipped horn, similar to that of females, but without dusky tones on the cutting edge of the mandible (lower portion of beak).[4] Females have the same plumage pattern as males, though with somewhat duller colouration.[5] The female has a grey head; buff supercilium, chin, and throat; black and warm brown upperparts; and off-white underparts. The bill of the female is pale yellow with the tip and cutting edge of mandible dusky. Juveniles are dull grey with a brown back, a pale yellow supercilium, and a pale horn bill.[4] Females and juveniles have hints of chestnut on their supercilium, shoulders, and throat, by which they may be distinguished from other sparrows, such as the Kenya Sparrow and the other rufous sparrows, which are common in much of the Chestnut Sparrow's range; or the House Sparrow, which also occurs in parts of its range.[4] Wing length ranges from 6.0 to 6.5 cm (2.4–2.6 in) in males and from 5.7 to 6.0 cm (2.2–2.4 in) in females. The tail, bill, and tarsus lengths are about Template:Cm to in, Template:Cm to in, and Template:Cm to in respectively.[4]
Voice
The basic call of the Chestnut Sparrow is a subdued chirp, with two recorded variations: a scolding threat call, rendered "chrrrrit" or chrrrrreeeerrrrrrrr" and a "chew chew" flight call. Displaying males give a high twittering trill, rendered as "tchiweeza tchiweeza tchi-tchi-tchi-tchi- see-see-see-seeichi".[2][6]
Taxonomy
This species was first described in 1880, by Gustav Hartlaub in the Journal für Ornithologie, as Sorella eminbey.[7] Hartlaub gave it the specific name eminibey in honour of the explorer Emin Pasha, and it is occasionally given the eponymous common name Emin Bey's Sparrow.[8] Hartlaub considered its 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.[8] 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.[9] 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.[8] These species are similar in their behaviour, which is adapted to the unpredictable conditions of their arid habitat. In particular, they share a courtship display in which males quiver their wings above their body.[10] 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 Dead Sea Sparrow shows similar displays, which may have evolved separately in a similar environment—an example of convergent evolution.[10] For a long time these species have been seen as highly primitive among the sparrows of the genus Passer, and only distantly related to the Palearctic black-bibbed sparrows such as the House Sparrow. For these reasons they are sometimes placed in a separate genus Auripasser.[10] However, a study of sparrow pseudogenes indicates that the Chestnut and golden sparrows are the closest relatives of the Palearctic black-bibbed sparrows.[11]
Distribution and habitat
The Chestnut Sparrow is found in East Africa along a broad band of mostly lower country from Darfur through southern Sudan, Somalia, Uganda, and Kenya to north-central Tanzania. Its range also extends northeast into the southwest and Great Rift Valley of Ethiopia.[1][12] Like the golden sparrows, it is sometimes nomadic when not breeding. Vagrants have been recorded as far from their breeding range as Dar es Salaam. It is found mostly in dry savanna and in fields and villages, but unlike its relations the golden sparrows, it is sometimes found in papyrus swamps.[12] Its population has not been quantified, but it appears to be common across a very large range and it is assessed by the IUCN Red List as Least Concern for global extinction.[1]
Behaviour
Chestnut Sparrows are gregarious, and are only occasionally found away from flocks. They frequently associate with queleas and other weavers.[12] Adults feed on grass seeds, and those near human habitations will also eat crumbs and other household scraps.[6] Nestlings are fed mostly softer grass seeds, and small beetles are also recorded in their diet.[13]
Breeding
The nesting behaviour of Chestnut Sparrow has been the subject of confusion. Early reports described the Chestnut Sparrow's nest as being a typical sparrow nest built in a tree; later it was reported that Chestnut Sparrows had elaborate nests like those of weavers.[14] In 1967, the ornithologist Robert B. Payne studied Chestnut Sparrows in a Grey-headed Social-weaver colony in an acacia grove near Lake Magadi in southern Kenya, and in 1969 he reported his findings in the ornithological journal The Ibis. Payne found that Chestnut Sparrows only nested by usurping the nests of the social-weavers.[13] After reporting this, and noting that the distribution of the Chestnut Sparrow closely coincides with that of the social-weavers of the genus Pseudonigrita, Payne suggested that the Chestnut Sparrow was an obligate nest parasite (not a brood parasite, like many Old World cuckoos and cowbirds).[13] Payne also noted in his paper that "Nest parasitism is generally thought to have been a stage in the evolutionary development of brood parasitism",[13] an idea that remains accepted,[15] and proposed the Chestnut Sparrow is likely to be evolving towards obligate brood parasitism.[5][13][16] However, it is known that besides parasitising the nests of weavers or using their abandoned nests, Chestnut Sparrows also build their own nests to incubate their eggs and raise their chicks. Nests built by Chestnut Sparrows, like most sparrow nests, are untidy domed structures which are made of grass and lined with feathers.[17] Its breeding season varies between different regions, following rains, and the breeding seasons of its hosts in areas where it parasitises nests; resultantly it has been recorded breeding in every month of the year across its range.[5]
At Payne's study locality the breeding season of the Chestnut Sparrow lagged behind that of its host. The sparrows began courting when the weavers started constructing their elaborate nests. Once the breeding season began, "the first impression was of the sparrows nesting and the Grey-capped Social Weavers unobtrusively skulking nearby".[13] Males displayed around the new weaver nests, crouching, raising and quivering their wings in a shallow V, and giving a high, twittering trill. The males were chased by the social-weavers, but returned persistently, until joined by females.[13] When a female came near a displaying male, the male would increase his rate of wing quivering, spread and depress his tail, and bow down his head, until his body formed an arc. This exaggerated display may be an adaptation related to pair formation in the absence of male nest-building,[13] and it may also serve to focus attention in breeding colonies and keep the birds in a colony together, as colonies are in clumps of trees surrounded by similar habitat.[10] During Payne's study, copulation was seen only in the acacias around the social-weaver nests. Females would fly to displaying males and solicit copulation in typical sparrow fashion, crouching, quivering, and drooping their wings.[13] When males saw displaying females, they would fly to them and mount them immediately. Males continued their wing quivering during copulation, and females would crouch, quiver, raise their head, and hold their tails horizontally. After a copulation the female would fly off and the male would continue displaying.[13] During this courtship and afterwards, males and mated pairs would interfere with the social-weavers' nest building, until they drove the social-weavers out. During Payne's study period, "Chases and fights between the two species were seen nearly every minute of observation", and the male sparrows spent about a fifth of their day annoying the social-weavers.[13] Little is recorded of incubation and fledging periods in the wild, except that clutches typically contain three or four eggs.[5] In captivity the incubation period lasts for 18 to 19 days. Some sources indicate that chicks are fed by the female alone.[2]
References
- ^ a b c Template:IUCN
- ^ a b c d Summers-Smith, J. Denis (2009). "Family Passeridae (Old World Sparrows)". Handbook of the Birds of the World. Volume 14: Bush-shrikes to Old World Sparrows. Barcelona: Lynx Edicions. ISBN 978-84-96553-50-7.
{{cite book}}: Unknown parameter|editors=ignored (|editor=suggested) (help) - ^ Summers-Smith 1988, p. 290
- ^ a b c d e Clement, Harris & Davis 1993, pp. 467–468
- ^ a b c d Summers-Smith 1988, p. 65
- ^ a b Summers-Smith 1988, p. 66
- ^ Hartlaub, Gustav (April 1880). "Ueber einige neue von Dr. Emin Bey, Gouverneur der Aequatorialprovinzen Aegyptens, um Lado, Central-Afrika entdeckte Vögel". Journal für Ornithologie (in German). 28 (2). doi:10.1007/BF02008812.
- ^ a b c Summers-Smith 1988, p. 61
- ^ Summers-Smith 1988, p. 305
- ^ a b c d Summers-Smith 1988, pp. 263, 290
- ^ Allende, Luis M. (2001). "The Old World sparrows (genus Passer) phylogeography and their relative abundance of nuclear mtDNA pseudogenes" (PDF). Journal of Molecular Evolution. 53: 144–154.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c Summers-Smith 1988, p. 62
- ^ a b c d e f g h i j k Payne, Robert B. (1969). "Nest Parasitism and Display of Chestnut Sparrows in a Colony of Grey-capped Social Weavers". The Ibis. 111 (3): 300–307. doi:10.1111/j.1474-919X.1969.tb02546.x. ISSN 1474-919X.
{{cite journal}}: Invalid|ref=harv(help) - ^ Summers-Smith 1988, p. 63
- ^ Davies 2000, pp. 243–244
- ^ Payne, Robert B. (May 1998). "Brood Parasitism in Birds: Strangers in the Nest". BioScience. 48 (5): 377–386.
- ^ Summers-Smith 1988, p. 64
Works cited
- Clement, Peter; Harris, Alan; Davis, John (1993). Finches and Sparrows: An Identification Guide. London: Christopher Helm. ISBN 0-7136-8917-2.
{{cite book}}: Check|isbn=value: checksum (help); Invalid|ref=harv(help) - Davies, Nick B. (2000). Cuckoos, Cowbirds, and other cheats. illustrated by David Quinn. London: T. & A. D. Poyser. ISBN 0-85661-135-2.
{{cite book}}: Invalid|ref=harv(help) - Summers-Smith, J. Denis (1988). The Sparrows. illustrated by Robert Gillmor. Calton, Staffs, England: T. & A. D. Poyser. ISBN 0-85661-048-8.
{{cite book}}: Invalid|ref=harv(help)
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