General Impact
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.
Location Specific Impacts:Australia 
Agricultural: Common Indian mynas (Acridotheres tristis) cause some depredation on fruit, especially figs (Frith 1979) Mangaia Is. (Cook Islands)
Competition: Mynas negatively effect native biodiversity by competing for nesting holes, preying on chicks and eggs and evicting small mammals. The myna poses a particular threat to Mangaia’s endemic vulnerable Mangaia kingfisher (see Todiramphus ruficollaris in the IUCN Red List of Threatened Species). Anecdotal evidence indicates that the kingfisher cannot breed successfully outside the small areas of Barringtonia asiatica forest on Mangaia because of interference from the myna. Fiji
Competition: Mynas are great adaptors to local food sources, which they can exploit very effectively to their advantage. In Fiji, the seashore along the main street in Suva (the capital) attracts hundreds of mynas at low tide, that proceed to feast on worms, molluscs, crustaceans and other seafood that has been stranded on the mud flats (Stoner 1923). Presumably this limits potential sources of food for native seabirds.
Disease transmission: Mynas 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.
Human nuisance: Described as “thrifty” and “pugnacious” the myna has the annoying habit of building nests in and around human habitations which may cause house keeping problems, for example when they construct nests in spouting and drain pipes.
Predation: Common Indian mynas (Acridotheres tristis) have been reported to predate on the eggs and young of terns (Sterna spp.) and noddies (Anous spp.) as recorded by Pernetta and Watling (1978). They also recorded agonistic behaviour by naturalised red-vented bulbuls (Pycnonotus cafer) with the common myna (amongst other species, including jungle myna (Acridotheres fuscus). In a form of role-reversal, the two mynas were themselves observed initiating attacks on bulbuls. Hiva Oa Is. (French Polynesia (Polynésie Française))
Other: It is possible that common mynas may have contributed to the decline of the red-moustached fruit dove and the Marquesas warbler by stealing their nests. Cave swiftlets (Collocalia spp.), on whose eggs common mynas are known to prey, are rare or absent (Holyoak and Thibault 1984, Seitre and Seitre 1992).
Predation French Polynesia (Polynésie Française) 
Interaction with other invasive species: Acridotheres tristis is suspected of contributing to the spread of invasive alien plants by consuming their fruit.
Predation: Acridotheres tristis is able of consuming the eggs or young native birds such as the Tahiti swiftlet (Collocalia leucocephalus) (Holyoak and Thibault 1984, Seitre and Seitre 1992).
Threat to endangered species: Acridotheres tristis is suspected of having contributed to the exclusion of certain species that are endemic to the Marquesas such as Acrocephalus caffer mendanae or Ptilinopus dupetitthouarsii. It represents a major threat to the Tahiti monarch, a species classified as Critically Endangered by IUCN (see Pomarea nigra in the IUCN Red List of Threatened Species) (Blanvillain et al., 2003). Moorea Is. (French Polynesia (Polynésie Française))
Predation: Cave swiftlets (Collocalia spp.), on whose eggs common mynas are known to prey, are rare or absent (Holyoak and Thibault 1984, Seitre and Seitre 1992).
Reduction in native biodiversity: Mynas may have contributed to the decline of the long-billed reed warbler (Holyoak and Thibault 1984) Tahiti Is. (French Polynesia (Polynésie Française))
Agricultural: In Tahiti, mynas eat cultivated fruits (Holyoak 1974).
Predation: Cave swiftlets (Collocalia spp.), on whose eggs common mynas are known to prey, are rare or absent (Holyoak and Thibault 1984, Seitre and Seitre 1992). Tel Aviv (Israel)
Competition: Mynas were observed taking over an active nest of a Syrian woodpecker (Dendrocopus syriacus).
Human nuisance: One roosting site included around 200 mynas, as well as other bird species, situated in a botanical garden over a public footpath (causing fouling problems).
Unknown: Since mynas are a relatively new invasive species to the region, and most of the population is in man-made habitat, it is too early to evaluate the actual and future impacts. Grand Terre Is. (New Caledonia) (New Caledonia (Nouvelle Calédonie))
Competition: Acridotheres tristis is believed to compete with local bird species for food and nesting sites (Pascal et al., 2006).
Interaction with other invasive species: Acridotheres tristis probably played a key role in the massive extension of Lantana camara (Virot, 1956 in Gargominy et al., 1996) New Zealand
Competition: In New Zealand mynas prey on the eggs and nestlings of feral pigeons, silver and southern black-backed or kelp gulls, as well as those of the small native and introduced passerines (Thomson 1922, Oliver 1955, Wodzicki 1965). Reunion (La Réunion)
Economic/Livelihoods: Mynas cause damage to fruits and affect production.
Interaction with other invasive species: Concerns have been raised on the role of mynas in the dissemination of exotic weeds. Reunion (La Réunion)
Interaction with other invasive species: Acridotheres tristis is suspected of contributing to the spread of invasive alien plants by consuming their fruit. Ascension Is. (Saint Helena)
Predation: Acridotheres tristis predate extensively on sooty tern eggs (Sterna fuscuta) (Hughes, 2004 in Varnham, 2006), there are reports that probably they cause more predation on sooty tern eggs than rats. Saint Helena
Competition: Acridotheres tristis competes with the 'Critically Endangered (CR)' endemic wirebird (see Charadrius sanctaehelenae in IUCN Red List of Threatened Species) for invertebrate prey (McCulloch and Norris, undated in Varnham, 2006).
Interaction with other invasive species: Acridotheres tristis depredates fruit trees and other crops. It is a major dispersal agent for invasive exotic plant species such as Opuntia stricta and Lantana camara. A. tristis is implicated in the spread of the invasive shrub wild currant (Ashmole and Ashmole, 2000 in Varnham, 2006) and in the spread of non-native Bermuda cedar (Rowlands et al., 1998 in Varnham, 2006).
Predation: Acridotheres tristis may raid nests of the 'Critically Endangered (CR)' endemic wirebird (see Charadrius sanctaehelenae in IUCN Red List of Threatened Species) and eat hatchlings and eggs (known to predate nests of other small birds) (McCulloch and Norris, undated in Varnham, 2006). Singapore
Fouling: Large communal roosts of mynas in urban environments cause problems; the noisy cheeky and intelligent bird increases noise pollution and also fouls the environment by depositing unhygienic droppings and creating other litter (Yap et al.. 20002, in Lim Sodhi Brook and Soh 2003).
Reduction in native biodiversity: The decline of the native hole-nesting oriental magpie robin (Copsychus saularis) in Singapore has been hypothesised to be linked to the presence of exotic mynas (Huong & Sodhi 1997, in Lim Sodhi Brook and Soh 2003). Hawaii (Hawai‘i) Is. (United States (USA))
Interaction with other invasive species: The common myna has aided the spread of lantana (Lantana camara) seeds - which is an invasive plant threatening the sustainability of native Hawaiian flora. Hawaiian Islands (United States (USA))
Interaction with other invasive species: Mynas indirectly affect the environment, largely through the dispersal of seeds. In 1858 the ornamental plant Lantana camara was introduced from Mexico (where it is harmless) to gardens in the Hawai‘ian Islands, where before long, common mynas were eating the berries (which were ignored by native species) to such an extent that correlative fluctuations were noticed in the abundance of fruits and mynas, the latter spreading the seeds (the germination of which is said to be increased by their passage through the bird) until rank growths of lantana became an agricultural nuisance (notes from Lever 1987: 497–498).
Predation: Byrd (1979) considered that common mynas may be significant predators of the eggs of wedge-tailed shearwaters (see Puffinus pacificus in IUCN Red List of Threatened Species) in the Hawai‘ian Islands, where in his study on Kauai some 23% of shearwater eggs were destroyed (notes from Lever 1987: 497–498).
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