The Javan myna (Acridotheres javanicus), 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 (Acridotheres grandis) or the jungle myna (A. fuscus), 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 (A. cinereus), which shares the same alternative name.

Description

thumb|Javan myna in flight, showing the distinctive white wing patches and tail bar

The Javan myna is a stocky, medium-sized bird measuring in length and weighing approximately . The species has since become extraordinarily successful, and is now the most common bird in Singapore.

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:

  1. 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.
  2. The bird rests its entire body on the ground or perch, including its head.

Diet

The Javan myna is omnivorous and highly opportunistic in its feeding habits. Its diet includes:

  • Invertebrates, particularly insects
  • Seeds and grains
  • Fruits
  • Nectar
  • Human food waste and scraps 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 (described onomatopoeically as "kaeeu kaeeu kaeeu"), 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.