Identification of pittas in the 'brachyura' complex in Asia: 1
by Frank Lambert, from Oriental Bird Club Bulletin 23, May 1996.
Introduction The four species of Asian pitta that share buff underparts and conspicuous blue wing patches - Indian Pitta, Pitta brachyura, Fairy Pitta, P. nympha, Blue-winged Pitta, P. moluccensis, and Mangrove Pitta, P. megarhyncha - are clearly closely related species. Historically they have received various different taxonomic treatments, but there is now almost universal recognition of four species, all apparently monotypic. Sibley and Monroe placed the four species in a 'brachyura' superspecies group. Although there can now be little doubt that there are indeed four species, the taxonomic relationships between them remain unclear. Differences between the species suggest that they should in fact be divided into two superspecies groups, with Indian and Fairy in one and Blue-winged and Mangrove in the other.
Three of the species overlap in range in South-East Asia, where, at certain times of the year, migratory Blue-winged Pitta can be found in the same areas as resident Mangrove or migratory Fairy Pittas. Indian Pitta is also migratory but has yet to be recorded in South-East Asia, although it is possible that it could occur as a vagrant. In the following account, a brief overview of the distribution, habitat, plumage and voice differences between the four species is given as an aid to identification in the field.
Distribution and habitat Initial identification of these four species can be narrowed down easily through a knowledge of distribution and usual habitat requirements.
Indian Pitta. Confined to the Indian subcontinent, where it is known as a breeding species in the foothills of the Himalayas, and a winter visitor in southern India and Sri Lanka. Apart from Mangrove Pitta, which has been found in the Sundarbans of Bangladesh, no other confusion species is present in the Indian subcontinent.
Fairy Pitta. Known to breed in southern Japan; on Koje Island and the southern slopes of Mt Halla, Cheju Island, both off southern Korea, and perhaps on the South Korean mainland; on Taiwan; and in eastern China south to Kwangsi and Kwangtung. In China, breeding has been confirmed in the provinces of Kwangsi, Anhwei and the mountains of Honan, and there are late April and May records from Kwangtung and Fukian that could refer to breeding birds or migrants. Records from around Shanghai refer to migrants.
During the non-breeding season, Fairy Pitta migrates south through eastern China and Taiwan to winter in Borneo and possibly southern China and Indochina. It has yet to be recorded in the Philippines. The evidence for wintering in southern China is poor, but January and February sightings in Hong Kong, perhaps of the same bird, can most easily be explained by an overwintering individual. Some evidence suggests that the birds wintering in Borneo are from mainland China, and it is possible that those from the more northerly part of the breeding range, in Japan and Korea, might winter in southern China or in Indochina. Fairy Pittas have been encountered several times in central Annam, Vietnam, in April.
Although it has been established that north-west Borneo is an important wintering area for Fairy Pitta, there are few records and it appears to be localised in its non-breeding range. There are no confirmed records from Sabah, only one record from Brunei and the only record from Indonesian Borneo is a specimen from Riam, South Kalimantan. In the 1970s, however, Fairy Pitta was a relatively common bird in Sarawak. Nevertheless, since that time, Fairy Pitta populations must certainly have declined in China, whilst elsewhere within its breeding range, it is reported to have become very rare. There were, for example, probably less than 20 pairs breeding on the islands off South Korea in 1994, whilst the best-known locality for Fairy Pitta in Japan, Mi-ike, Miyazakiken, holds only around 20 birds in most years. It has been suggested that large-scale bird trapping in the spring on Taiwan has depleted the island's breeding population, and may also have affected migrant populations: at Tseng-Wen reservoir, hundreds of Fairy Pittas were caught each spring during the 1980s, with as many as 200 being caught on a single day.
Blue-winged Pitta. The species most likely to be confused with Mangrove Pitta, since it sometimes breeds in adjacent habitats and also occurs in mangroves during migration. Usually, however, it is a bird of a wide variety of other wooded habitats. Blue-winged Pitta has a very wide distribution in South-East Asia, being known to breed in southern Yunnan, China; Annam and Cochinchina, Vietnam; Cambodia; Laos; the southern Shan States, Pegu Hills, Karen Hills and south Arakan to Tenasserim, Burma (Myanmar); Thailand; and Perlis and Langkawi Island, northern Peninsular Malaysia. Evidence also suggests that some individuals breed in Borneo. The occurrence of migrants in the Red River delta of Vietnam suggests that Blue-winged Pitta may also breed in Tonkin or in adjacent China, perhaps in Guangxi Province.
During the northern winter, Blue-winged Pitta is found throughout the southern part of the breeding range, but more northern areas are vacated as the dry season sets in, and birds migrate south to Peninsular Malaysia, Sumatra and Borneo, with birds recorded from many islands in this region. It is possible that some individuals in the northern part of the range may stay on their breeding grounds all year, as birds have been seen in winter in the Pegu Hills of Burma (Myanmar). Vagrants have reached Tawitawi, Basilan and Palawan in the Philippines; north Sulawesi; Christmas Island and north-west Australia, although records from the latter have been questioned. Although Blue-winged Pitta may reach Java during the winter, there are as yet no acceptable records. In its wintering range, Blue-winged Pitta, in contrast to Fairy Pitta, apparently favours secondary forest or forest edge, not usually being encountered in primary forest, and, although it may be found at high altitudes during migration, it usually winters in lowlands and hills.
Mangrove Pitta. As its name suggests, Mangrove Pitta is only certainly known from mangrove forest, so habitat is key to its identification. It ranges from the Sundarbans south along the coast of mainland Asia, to Singapore and Sumatra, and northwards up the east coast of Peninsular Malaysia. It has also been found in mangroves on many small offshore islands.
Field Identification The two superspecies groups form two relatively distinctive species pairs that are superficially very similar. Blue-winged and Mangrove Pittas are medium-sized pittas, whilst Indian and Fairy Pitta are smaller, with Indian Pitta distinctly smaller and Fairy Pitta somewhat intermediate. There is a similar spectrum of bill sizes, with Mangrove having the largest and Indian the smallest.
Indian Pitta. Unlikely to be confused with any other pitta in its range. However, as noted, Mangrove and Blue-winged Pittas both occur in areas where vagrant Indian Pittas could potentially occur. These two species are overall larger and darker, with much more extensive violet-blue, rather than azure-blue, wing patches, violet-blue rumps and broad bold buffy supercilia. They also have considerably more white in the wing and a more chestnut-coloured superciliary band. Both lack the small whitish patch below the eye and the white in the supercilum of Indian Pitta. Immature Mangrove and Blue-winged Pittas also have more extensive blue in the wing and are a richer, orange-buff, below, when compared to similar-aged immature Indian Pittas. It should also be noted that immature Hooded Pittas, Pitta sordida, which may be found in the same areas as breeding Indian Pittas, have black heads with chestnut crown to nape, and a prominent white bar across the wing coverts.
Fairy Pitta. As noted previously, this species may be found within the potential range of Blue-winged Pitta during migration. Fairy Pitta is paler below than Blue-winged Pitta, has an azure-blue rather than violet-blue wing patch and rump and a more contrasting head pattern. In flight, there is considerably less white in the wing of Fairy than Blue-winged.
Blue-winged Pitta and Mangrove Pitta. Mangrove Pitta is slightly more robust and larger-billed than Blue-winged (bill >38 mm in length, compared with <32.5 mm), although this may be of little value to a first-time observer obtaining a brief view. Head patterns of these two species, however, also differ, with Mangrove Pitta having distinctly less contrast between the lateral coronal bands (darker than those of Blue-winged) and the more uniform, darker brown crown. Blue-winged Pitta has conspicuous buffy or buffy-brown lateral coronal bands that contrast strongly with the rest of the crown. It also has more black in the top of the crown than Mangrove. If views are exceptionally good, the black chin of Blue-winged Pitta is diagnostic (white in Mangrove). Immature Mangrove Pitta is very similar to immature Blue-winged Pitta, but, like the adult, has a notably larger bill, white chin and the entire crown is brown with variable rufous tones (depending on age) and dark edges to the feathers, giving a scaly appearance.
Voice Calls of the four species in this group are all distinctive, and can be used to separate potentially sympatric species.
Indian Pitta. Quite different from the other species, being a clear short double whistle (of monosyllabic notes) 'wheeet-tieu' or 'wieet-pyou' or occasionally, a triple note 'hh-wit-wiyu'. Calling at dawn and dusk also occurs on the wintering grounds, and the Tamil name translates as the 'six-o'clock bird'. In Sri Lanka, Drongos, Dicrurus sp, and Golden-fronted Leafbird, Chloropsis aurifrons, may imitate the call of Indian Pitta, and it is possible that such species may also imitate the calls of other pittas in other parts of their range.
Fairy Pitta. A clear double whistle, similar to that of Blue-winged Pitta, but it is notably longer and slower and comprises two disyllabic notes: 'kwah-he kwa-wu'.
Blue-winged Pitta. A loud, clear, fluty double-whistle 'taelaew-taelaew' or 'taewu-taewu' with a distinctive disyllabic quality to both parts ('tae-laew') of the call. The entire call lasts less than a second. A second call, given in alarm, is a harsh, skyeew. Calling is rather seasonal, occurring mostly during the breeding season. During the non-breeding season, they are usually silent except at dawn and dusk, when they may occasionally call, sometimes from their roosts.
Mangrove Pitta. Also loud and fluty, lasting less than a second. The notes, best described as 'hhwa-hwa' are however more even, with no suggestion of the disyllabic quality of Blue-winged Pitta. The first note rises, but the second is fairly even. At a distance, the call may sound more like the 'tae-laew' of Blue-winged Pitta but, unlike the latter, is not given in couplets, so each, 'tae-laew' phrase is separated from the next by a distinctive pause that may last 3-4 seconds. The call is usually made from the canopy or tree-tops, but, unexpectedly, this species has also been heard calling from within its nest.
Conclusion Although these four species of pitta are often easy to observe on their breeding grounds, particularly when calling, the three species found in South-East Asia during the northern winter are often silent and difficult to see well. Under these circumstances, prior knowledge of the differences to look for is critical, since they tend to disappear without trace once disturbed. It is useful to bear in mind, however, that at least two species in this group, Indian and Blue-winged Pitta, are apparently territorial on their wintering grounds, so that patience may often pay dividends if one waits or revisits the exact area where a, brachyura, complex pitta was glimpsed.
Acknowledgements Production of the photographs in the original article in OBC Bulletin 23 was sponsored by Natural History Book Services. The Bulletin article also contains the relevant plate and distribution maps from the new book 'Pittas, Broadbills and Asities' by Frank Lambert and Martin Woodcock, published by Pica Press.