Javan myna
The Javan myna, also known as the white-vented myna, is a species of myna in the starling family Sturnidae. It is native to Java and Bali in Indonesia, where its population has declined significantly due to excessive trapping for the cage-bird trade. Paradoxically, while the species is considered vulnerable in its native range, it has become a highly successful invasive species in several other countries, most notably Singapore, where it is now the most abundant bird species. The species has been introduced to southeastern Thailand, southern Malaysia, Sumatra, Taiwan, Japan, Nepal, and Puerto Rico.
The Javan myna is a medium-sized, predominantly black bird with distinctive white wing patches visible in flight, yellow bill and legs, and lemon-yellow eyes. It is highly adaptable and thrives in urban environments, where it feeds on a variety of foods including insects, fruit, seeds, nectar, and human food waste. The species is known for its bold behaviour around humans and its loud, varied vocalisations.
Taxonomy
The Javan myna was formally described by German ornithologist Jean Cabanis in 1851. The species is placed in the genus Acridotheres, which contains several myna species native to Asia.The Javan myna is sometimes considered conspecific with the great myna or the jungle myna, though most authorities treat it as a distinct species. The International Ornithologists' Union recommends avoiding the alternative common name "white-vented myna" to prevent confusion with the pale-bellied myna, which shares the same alternative name.
Description
The Javan myna is a stocky, medium-sized bird measuring in length and weighing approximately.The plumage is mainly black with a slight glossy sheen. The wings are brownish-black, and the primary feathers have white bases that form a striking white wing bar visible during flight. A white tail bar is also displayed in flight. The undertail coverts are white, which is the basis for the alternative name "white-vented myna". A short, erect crest adorns the forehead. The beak, legs, and feet are bright yellow. The iris is lemon-yellow, which distinguishes it from the common myna, which has a brown iris.
Immature birds are browner and duller than adults, with less prominent crests and paler soft parts.
Distribution and habitat
Native range
The Javan myna is native to Java and Bali in Indonesia. In its native range, the species has experienced significant population declines due to heavy trapping pressure for the cage-bird trade, and is now considered uncommon to rare in many areas where it was formerly abundant.Introduced range
The species has been introduced, either deliberately or accidentally through escaped cage birds, to numerous locations across Asia and beyond:- Southeast Asia: southeastern Thailand, southern Malaysia, Singapore, Sumatra, and the Lesser Sunda Islands
- East Asia: Taiwan and Japan
- South Asia: Nepal
- Caribbean: Puerto Rico
Invasive populations
Singapore
Javan mynas were first introduced to Singapore in the 1920s through the cage-bird trade, when Singapore was a major colonial trading hub under the British Empire. The species has since become extraordinarily successful, and is now the most common bird in Singapore. Studies have found that the Javan myna comprises a substantial proportion of the total bird population in urban areas of Singapore.The success of the Javan myna in Singapore has been attributed to several factors, including its highly adaptable diet, tolerance of human activity, aggressive behaviour towards competing species, and the abundance of nesting sites in urban structures. The species is thought to have contributed to the decline of the formerly common common myna and the native Oriental magpie-robin in Singapore through competition for food and nesting sites.
Behaviour and ecology
Social behaviour
Javan mynas are gregarious birds that are typically found in pairs or small groups. They associate in larger flocks at favoured feeding sites and communal roosts. The species is notably bold and shows little fear of humans; individuals often remain in place even when approached to within two metres.When foraging, Javan mynas typically scavenge in groups of two to four or more individuals. Usually, one bird acts as a sentinel, keeping watch from a vantage point while the others feed. If the sentinel detects a potential threat, it alerts the group with a high-pitched alarm call, prompting all members to flee the area swiftly.
The species is territorial and frequently engages in noisy confrontations. Fights typically involve two pairs of birds and occur over territory, mates, or food resources. During combat, an aggressor will attempt to pin its opponent to the ground, gaining a positional advantage from which to deliver strikes. These encounters usually last between one and ten minutes, and the objective appears to be establishing dominance rather than causing serious injury. Fights typically end with the losing party retreating.
Intelligence and problem-solving
Javan mynas demonstrate considerable adaptability and learning ability. In one documented case, a myna learned to activate an automatic door by flying up to its motion sensor, enabling it and its mate to exit a building.Roosting
Javan mynas form large communal roosts, often gathering in trees in urban areas. Two sleeping postures have been documented:- The bird supports itself on its tarsi and rump, with its head tucked to one side of its shoulder and eyes closed by raising the lower eyelids.
- The bird rests its entire body on the ground or perch, including its head.
Diet
- Invertebrates, particularly insects
- Seeds and grains
- Fruits
- Nectar
- Human food waste and scraps
Breeding
Javan mynas are monogamous and form pair bonds. They are cavity nesters, building nests in holes in trees, buildings, and other structures. In urban areas, they commonly nest in gaps in buildings, roof spaces, air conditioning units, and similar cavities.Eggs and incubation
The female lays a clutch of 2–5 eggs, which are blue in colour. The incubation period is 13–14 days. After hatching, the adults remove the eggshells from the nest and dispose of them some distance away, a behaviour thought to reduce the risk of attracting predators to the nest.Fledging and parental care
The fledgling period lasts approximately 25 days. Juvenile birds beg for food with incessant high-pitched, scratchy calls, accompanied by characteristic "half-flaps" and wing quivering. Adults feed the young with food items such as small seeds, fruits, and insects, which are delivered directly rather than regurgitated.Vocalisations
The Javan myna has a varied vocal repertoire similar to that of the common myna. Calls include loud whistles, chattering, and harsh, grating notes. The species is often vocal, particularly at communal roosts where large numbers gather in the evening and produce a considerable cacophony.Conservation status
The Javan myna is listed as Vulnerable on the IUCN Red List. This assessment refers to the species' status in its native range of Java and Bali, where populations have declined substantially due to intensive trapping for the cage-bird trade. Keeping songbirds in cages is a deeply rooted cultural tradition in Indonesia and other parts of Southeast Asia, and the Javan myna is among the many species affected by this practice.The species' situation represents an unusual conservation paradox: while it is threatened in its native range, it has become superabundant and even problematic as an invasive species in several countries where it has been introduced.