It is overall green-glossed black plumage, purple-tinged on the head and neck. There are large white wing patches which are obvious in flight but mostly covered when the bird is sitting. The bill and strong legs are bright yellow, and there are yellow wattles on the nape and under the eye. These differ conspicuously in shape from the naked eye-patch of the Common Myna and Bank Myna (A. ginginianus), and more subtly vary between the different hill mynas from South Asia: in the Common Hill Myna they extend from the eye to the nape, where they join, while the Sri Lanka Hill Myna has a single wattle across the nape and extending a bit towards the eyes. In the Southern Hill Myna, the wattles are separate and curve towards the top of the head. The Nias and Enggano Hill Mynas differ in details of the facial wattles, and size, particularly that of the bill. The Nias variety is exceptional in size and superior speech capability, and is becoming increasingly rare.
Sexes are similar; juveniles have a duller bill.
With the Southern, Nias and Enggano Hill Mynas as separate species, the Common Hill Myna has seven or eight subspecies which differ only slightly. They are:
- Gracula religiosa andamanensis Beavan 1867 – Andaman Hill Myna. Andaman Islands, Central (Nancowry) group of the Nicobar Islands
- Gracula religiosa batuensis – Batu and Mentawai Islands.
- Gracula religiosa halibrecta Oberholser 1926 – Great Nicobar Hill Myna. Great Nicobar Little Nicobar and adjacent islets in the Nicobar Islands. Doubtfully distinct from andamanensis.
- Gracula religiosa intermedia – North-western Indochina and adjacent north-eastern India and southern China.
- Gracula religiosa palawanensis – Palawan in the Philippines.
- Gracula religiosa peninsularis – Bastar Hill Mynah. Central India.
- Gracula religiosa religiosa – Greater Sundas (except Sulawesi) and Peninsular Malaysia.
- Gracula religiosa venerata – Western Lesser Sundas.
Vocalisations
The Common Hill Myna is often detected by its loud shrill descending whistles followed by other calls. It is most vocal at dawn and dusk when it is found in small groups in forest clearings high in the canopy.
Both sexes can produce an extraordinarily wide range of loud calls – whistles, wails, screeches, and gurgles, sometimes melodious and often very human-like in quality. Each individual has a repertoire between 3 and 13 such call types, which may be shared with some near neighbours of the same sex, being learned when young. There is a very rapid change of dialect with distance, such that birds living more than 15 km apart have no call-types in common with one another.
Unlike some other birds, such as the Greater Racket-tailed Drongo, the Common Hill Mynas do not imitate other birds in the wild, although it is a widely held misconception that they do. On the other hand, in captivity, they are among the most renowned mimics, perhaps on par only with the African Grey Parrot (Psittacus erithacus). They can learn to reproduce many everyday sounds, particularly the human voice, and even whistled tunes, with astonishing accuracy and clarity.
Distribution and ecology
This myna is a resident breeder from Kumaon division in India (80° eastern longitude) east through Nepal, Sikkim, Bhutan and Arunachal Pradesh, the lower Himalayas, terai and foothills up to 2000 m ASL. Its range continues east through Southeast Asia northeastwards to southern China, and via Thailand southeastwards across northern Indonesia to Palawan in the Philippines. It is probably not found anymore in Bangladesh due to habitat destruction and overexploitation for the pet trade. A feral population on Christmas Island has likewise disappeared. Introduced populations exist in Puerto Rico and perhaps in the mainland USA and possibly elsewhere; feral birds require at least a warm subtropical climate to persist.
This myna is almost entirely arboreal, moving in large noisy groups of half a dozen or so, in tree-tops at the edge of the forest. It hops sideways along the branch, unlike the characteristic jaunty walk of other mynas. Like most starlings, the Hill Myna is fairly omnivorous, eating fruit, nectar and insects.
They build a nest in hole. The usual clutch is 2-3 eggs.
Pet trade and conservation forms within the species complex
The hill mynas are popular cage birds, renowned for their ability to imitate speech. The widely-distributed Common Hill Myna is the one most frequently seen in aviculture. Demand outstrips captive breeding capacity, so they are rarely found in pet stores and usually purchased directly from breeders or importers who can certify that the birds are traded legally.
This species is widely distributed and locally common, and if adult stocks are safeguarded it is able to multiply quickly. On a worldwide scale, the IUCN thus considers the Common Hill Myna a Species of Least Concern. But in the 1990s, nearly 20,000 wild-caught birds, mostly adults and immature grown-ups, were brought into trade each year. In the central part of its range, G. r. intermedia populations have declined markedly, especially in Thailand which supplied much of the thriving Western market. Its neighbor countries, from where exports were often limited due to political or military reasons, nevertheless supplied a burgeoning domestic demand, and demand in the entire region continues to be very high. In 1992, Thailand had the Common Hill Myna put on CITES Appendix III, to safeguard its stocks against collapsing. In 1997, at request of the Netherlands and the Philippines, the species was uplisted to CITES Appendix II. The Andaman and Nicobar Islands subspecies andamanensis and (if valid) halibrecta, described as "exceedingly common" in 1874, qualified as Near Threatened in 1991. The former is not at all common anymore in the Nicobar Islands and the latter – if distinct – has a very limited range.
