| Iago Sparrow | |
|---|---|
| Male (above) and female (below) at Sal | |
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Suborder: | Passeri |
| Family: | Passeridae |
| Genus: | Passer |
| Species: | P. iagoensis |
| Binomial name | |
| Passer iagoensis (Gould, 1837) |
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| Synonyms[2][3] | |
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Pyrgita jagoensis Gould, 1837 |
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The Iago Sparrow (Passer iagoensis), is a passerine bird of the sparrow family Passeridae. It is also known as the Cape Verde Sparrow and the Rufous-backed Sparrow. It is endemic to the Cape Verde Islands, in the eastern Atlantic Ocean.
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The Iago Sparrow is a small sparrow, 12.5–13 centimetres (4.9–5.1 in) long, with a wing length of 5.5–6.9 centimetres (2.2–2.7 in).[4] The male has a black or greyish-black crown and eyestripe, a grey nape and a small patch of white on the lower forehead. The sides of the head, especially above the eye, are a rich cinnamon colour. The scapulars are white and brown, while the rest of the upperparts are brown, streaked with black and beige. The cheeks and underparts are pale grey, and the throat and chin are marked with a small black bib. The female is grey-brown, with black-streaked wings and breast, and pale grey underparts. It is very similar to the female House Sparrow but has a more apparent pale stripe over the eye. The juvenile resembles the adult female, but young males are more chestnut from an early age, with a trace of a black bib on the chin.[4][5] In 1898, British ornithologist Boyd Alexander reported that adults begin moulting in early February, and some birds were still in moult by late May.[6][7]
The Iago Sparrow's vocalisations include calls, varying between the sexes, elaborations of these called 'songs', and an alarm call. Calls are chirps, somewhat similar to those of other sparrows, the usual version made by males described as a "twangy" cheesp or chew-weep, and that of females described as a "more sibilant" chisk. The song is a long, elaborated series of call notes, and is made by breeding males in their nests. An alarm call like that of other sparrows, transcribed chur-chur-chur, is also used.[7]
The Iago Sparrow was first collected by Charles Darwin during the first stop of the second voyage of HMS Beagle at Santiago island, then called St. Jago.[2] It was described for him by zoologist John Gould, in the 1837 volume of the Proceedings of the Zoological Society of London, and given the name of Pyrgita iagoensis.[8] By the time Gould wrote The Zoology of the Voyage of H.M.S. Beagle with Darwin and three other zoologists in 1841, he had placed the Iago Sparrow in the genus Passer, in which it has since been placed.[2][5] The genus, among the sparrows of the Old World in the family Passeridae, also contains at least 20 other species, among them the House Sparrow and Eurasian Tree Sparrow. Within its genus, the Iago Sparrow has been considered one of the African 'rufous sparrows', a group which also includes species such as the Great Sparrow (Passer motitensis). Treatments of these birds as distinct species were usually followed until Reginald Ernest Moreau, writing in the 1962 The Check-list of the Birds of the World, merged the Iago Sparrow and the mainland rufous sparrows as Passer motitensis.[2] This taxonomy was followed frequently until J. Denis Summers-Smith argued in the 1980s that the Iago Sparrow's many differences in morphology and behaviour, and separation from the other rufous sparrows by about 5,000 kilometres (3,100 mi) are sufficient grounds for species status.[2][9][10] Studies of mitochondrial and nuclear DNA further suggest it may be a close relative of the House Sparrow and the Spanish Sparrow, rather than the rufous sparrows.[11]
French ornithologist Émile Oustalet described a specimen from Branco as a separate species Passer brancoensis in 1883,[2] which was recognised as a subspecies recognised by W. R. P. Bourne, who claimed to observe differences between birds from different islands.[12] According to Bourne, birds of Passer iagoensis iagoensis on more wooded islands in the south are darker and larger, and also behave more like House or Spanish Sparrows, competing with them better in human-altered habitats.[12] He later wrote that the variations he saw comprised two clinal trends, of increasing darkness towards the south, and of smaller size further from the continental coast.[13] Charles Vaurie, examining differences in plumage and measurements of specimens in major museums, did not find any significant variation, and Vaurie and Summers-Smith both did not recognise any subspecies.[2][14]
The Iago Sparrow is endemic to the Cape Verde Islands.[4] It is common on most islands, excluding Fogo (from which it is absent) and Santa Luzia, Branco and Sal (in which it is scarce). It can be found in a variety of habitats, including flat lava plains, cliffs, gorges, and edges of farmland, at altitudes of up to 1,200 metres (3,900 ft). It has also been seen in urban areas and gardens on islands, where it occurs alongside the House Sparrow, but not the Spanish Sparrow. In agricultural areas the bird may do some damage to crops, mostly by eating buds and shoots.[4] The Iago Sparrow is highly common in its limited range, though its exact population is not known. Though it may be at risk to unpredicted changes in its environment, due to its limited range, it is assessed as Least Concern by the IUCN Red List.[1]
The Iago Sparrow is gregarious, usually breeding in small colonies, and forming large flocks outside the breeding season. It is not shy, allowing humans to approach it even at its nest. It is attracted to water, which is scarce in its habitat. It often is seen dust bathing in small groups.[15]
The adult sparrow feeds mainly on seeds, but also on insects and shoots. Nestlings, by contrast, feeds almost exclusively on insects.[4][6][16] It forages mostly on the ground, moving restlessly and close to the ground. It flocks with other birds, even warblers such as the Blackcap and the Cape Verde Swamp-warbler.[15][17]
This sparrow's breeding habits are not well known, though they are believed to be similar to those of the House Sparrow.[4] Its breeding season begins in August and September with the onset of the humid season. The Iago Sparrow builds its nest in a variety of habitats, including lava plains, cliffs, and gardens. The nest is made of grass, lined with hair and feathers and usually built in a hole in a cliff or wall. The average clutch is three to five eggs.[4]
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