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.

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.