Taxonomic name: Acridotheres tristis (Linnaeus, 1766)
Synonyms: Acridotheres tristas (Linnaeus, 1766)
Common names: brun majna (Swedish), common myna (English), hirtenmaina (German), hjarðmænir (Icelandic), Indian myna (English), Indian mynah (English), kabairohakka (Japanese), maina (Danish), mainá común (Spanish), maina comune (Italian), mainato (Portuguese), majna brunatna (Polish), majna obecná (Czech), Martin triste (French), merle des Moluques (French), mynah (English), pihamaina (Finnish), treurmaina (Dutch)
Organism type: bird Acridotheres tristis is native to India and the Middle East. Acridotheres can be translated as “grasshopper hunter” which reflects the birds insectivorous diet; a trait that lead to its introduction into many Pacific islands to control insect pest populations of commercially important crops. The unfortunate and unseen result was that the birds preferred to feed on the agricultural crops themselves. In Australia it has been noted to compete with native birds and small mammals for nesting sites and consume their eggs and chicks. Description
Acridotheres tristis is approximately 25-26cm in length with a relatively heavy build. The head, neck and upper breast of the adult is glossy black, while the undertail coverts, tail tip and the outer feathers are white.The bill, legs and feet are bright yellow, while the adult iris is reddish brown. Male and female A. tristis are not clearly sexually dimorphic and are thus difficult to identify in the field (Counsilman Nee Jalil and Keng 1994).
Mynas are distinctive in that they walk rather than hop. Like most territorial birds they have a bout of intense calling in the early morning that lasts between 5 and 15 minutes. Males call more often than the females and pairs sometimes duet. The territorial call is a rowdy medley of notes, raucous, gurgling, chattering, even bell-like sounds, in rapid sequence. Adults with young chicks utter harsh squalking noises and young learning to fly emit persistent "chi-chi-chis". At their communal roosts mynas maintain a noisy chattering well after nightfall and before dawn. Similar Species
Manorina melanocephala
More
Occurs in:
agricultural areas, urban areas Habitat description
Acridotheres tristis inhabit open countryside, close to human establishments and tend to avoid dense forests. They are primarily situated near flood plains, grasslands, cultivated areas, plantations, villages, towns and cities, as well as desert oases and the foothills of various mountainous ranges (Feare and Craig, 1999). Mynas are originally from tropical climates but have a surprising ability to adapt to a wide range of climates and habitats. For example, in Fiji they frequently congregate on the seashore and have even colonised a small coral island. They prefer warm climates and inhabit areas with plentiful and accessible food resources. This is important as their eggs are prone to chilling below the minimum temperature needed to maintain them. Interestingly, in New Zealand, they avoid the colder regions in the South Island (such as Nelson), but have established a stable population near piggery sheds, where sufficient heat is produced by the pigs to maintain a relatively high temperature; in addition, there is an abundant source of pig food available (P.R. Wilson Pers. Comm.). In Singapore, mynas commonly roost among monoclonal stands of tall densely canopied trees (Hails 1985; Yap et al. 2002). In Fiji, less densely canopied trees such as coconut palms are chosen for roosting and refuge (Stoner 1923).
The myna is a good adaptor to local environments. In Singapore it is strongly associated with agricultural and farm areas (Lim Sodhi Brook and Soh 2003). In Australia, on the other hand, reserves are a preferred habitat (specifically, mynas are prevalent around the edges, rather than the interior of the reserve) (Pell and Tidemann 1997). While reserves provide an excellent environment for the myna and stimulate large numbers of mynas during the breeding season, during the winter months mynas in Australia appear to find refuge in the surrounding suburban areas (Pell and Tidemann 1997). General impacts
Acridotheres tristis may prey on the eggs and nestlings of other birds and aggressively defend territories and nesting sites, which is obviously of great concern if native bird species are affected. This has been particularly concerning in Australia where hollows are in short supply (due to the clearing of large tracts of bush for agriculture) and there have even been observations of mynas filling up any nearby vacant nesting hollows with rubbish to discourage other birds from nesting in their territory (Tidemann 2005; Thomas 2004). In New Zealand feral pigeons, silver and southern black-backed or kelp gulls and small passerine species are affected (Thomson 1922; Oliver 1955; Wodzicki 1965). In Australia Acridotheres tristis will even evict large birds, such as kookaburras and dollar birds and small mammals, such as sugar gliders, from their nests (Tidemann 2005). Mynas may also exhibit “mobbing” behaviour against birds or mammals (which is a problem in Australia, where native opossums are affected) (Tidemann 2005).
Mynas may consume grapes, apricots, apples, pears, strawberries, gooseberries and other fruit, damaging food crops (Heather and Robertson 1997). Mynas may be a source of annoyance to humans due to their communal roosting behaviour; especially in highly populated areas. In Singapore, for example, the common myna and the white-vented myna (A. javanicus) form a combined estimated population of around 160,000 (Lim Sodhi Brook and Soh 2003). In such high densities mynas have proved to be a human nuisance. The disruptive noise and fouling of the environment through droppings and other associated mess cause a variety of problems (Yap et al. 20002, in Lim Sodhi Brook and Soh 2003). In Fiji they have also proven to be a residential nuisance as they build nests in spouting and drainpipes (Stoner 1923). Mynas fearlessly steal food from plates in cafes and restaurants, which is a hygiene or general nuisance problem. It has been considered that they may also spread mites and diseases that affect people and farmstock (Tidemann 2005). Specimens in Fiji have been identified as carrying owl flies, biting lice, thread worms (of a species of Oxyspirrura) and round worm (Stoner 1923). Presumably, populations of the bird may provide reservoirs of a disease that affects native birds, while themselves remaining largely unaffected. Notes
In India, Acridotheres tristis is referred to as the farmer’s friend as it protects crops by feeding on insect pests. Many myna species, including Acridotheres tristis are accomplished mimics and can be taught to speak; for this reason mynas are sometimes used as pets (Tidemann 2005). Geographical range
Native range: Acridotheres tristis originated from central and southern Asia and is widely distributed throughout India (Feare & Craig 1999, in Lim Sodhi Brook and Soh 2003). Their approximate range is from eastern Afghanistan to India and from Sri Lanka to Bangladesh.
Known introduced range: Mynas spread throughout much of Southeast Asia in the 1900s and have been widely introduced around the world. They are established in South Africa, eastern and southeastern Australia, North Island of New Zealand, Solomon Islands, New Caledonia, Fiji, Western Samoa, Cook Islands, Hawaii and Réunion. Recently, reports have detailed breeding of common mynas in northern France. (P. Clergeau Pers. Comm. 2005, Feare & Craig 1999). Introduction pathways to new locations
Acclimatisation societies:
Taken to botanical garden/zoo: In Israel, mynas escaped from a private facility of exotic birds in the centre of the Tel Aviv public park.
Local dispersal methods
Escape from confinement:
Natural dispersal (local): Escaped mynas breed in the wild. Management information
In Australia a risk assessment model developed by the Bureau of Rural Sciences has been used as a basis for classifying the risk exotic species pose in Australia (Bomdord 2003). The model, partly based on the ability of the species to establish colonies and be a pest, places the common Indian myna (Acridotheres tristis) in the highest threat category.
Preventative measures: Long term management practices may include the modification of habitats, the limitation of resources and education of the public. Attempts to restrict food may be fraught with difficulty as the myna’s highly varied diet allows it to resort to other sources of food, even if its preferred food is removed (Thomas 2004). Physical:The highly intelligent myna learns to avoid traditional traps. Dr Chris Tidemann at the Australian National University hypothesises that this is due to their ability to interpret the distress calls of any trapped mynas and thus avoid the traps (Thomas 2004). Ironically the type of trap currently being trialled and used in Australia is based on the concept of providing the mynas with a “home away from home” for a few days prior to trapping; by providing food, shelter and perches in cages. The traps encourage more mynas to visit and roost inside; the birds are eventually killed with carbon dioxide (Thomas 2004).
Integrated management: This may be a promising course of action, as invasive bird species are frequently associated with human modified environments (Lim Sodhi Brook and Soh 2003). Nutrition
Acridotheres tristis are predominently ground feeders, but will opportunistically feed on flowering or fruiting trees and bushes (Feare and Craig 1999). Their diet is highly variable, based on location and they will feed on invertebrates, fruit, grain, birds’ eggs, small reptiles and food scraps. They are highly adaptable to local food supplies, even taking advantage of anything from pet food to fledgling sparrows (Australian Museum 2003). They feed on a wide variety of invertebrates, including beetle larvae and adults, caterpillars, worms, flies, snails and spiders. They scavenge around rubbish dumps, pastures and farmyards; roads provide a good source of small dead invertebrates and other animals. In addition, they are known to feed on the fruits and seeds of many cultivated plants, such as papaya, dates, apple, pear, tomato.
Mynas exploit local and temporary food sources effectively. One example is in Suva, Fiji, where the seashore along the main street attracts hundreds of mynas at low tide, which proceed to feast on worms, molluscs, crustaceans and other seafood that has been stranded on the mud flats (Stoner 1923). In their native range of southern Asia, however, the myna forms flocks in rural areas, feasting on insects and grubs turned up in the soil by the ploughs (Australian Museum 2003). Reproduction
Acridotheres tristis pairs stay together returning to the same territory each year. They build a cup shaped nest from dry grass, twigs and leaves. They may construct their nest in a tree hollow, on a cliff or a building or in a thick tangle of vegetation. Mynas usually raise two broods per season, laying up to six greenish-blue eggs in each brood (with an average of four). The female incubates the eggs for 13 to 14 days. The fledging period lasts between 20 to 32 days (an average of 25 days). Parents feed the chicks as long as three weeks after they have left the nest. Juveniles form small flocks and may form mating pairs at as young as nine months old (although few breed in their first year).
In New Zealand they lay eggs from mid-October to early March, with the highest egg-laying activity occurring from November to January. In Hawke's Bay in New Zealand, some mynas (identified by colour-banding) were found to have lived over 12 years. This species has been nominated as among 100 of the "World's Worst" invaders Reviewed by: Major update under progress
Dr. Charlotte Yap Aye May and Dr. Navjot S Sodhi, Department of Biological Sciences, National University of Singapore. Singapore Principal sources: Ohad Hatzofe, Division of Science & Conservation Division, Israel Nature & Parks Authority
Compiled by: IUCN/SSC Invasive Species Specialist Group (ISSG)
|
|
Last Modified: Wednesday, 19 July 2006
|
