Étude de cas sur les impacts
Agricole: The common myna has the potential to become a serious economic pest species in Australia because it is known to damage fruit crops (Dawson & Bull 1970, Wilson 1973, Lever 1987, in Martin 1996) and young vegetable crops (Frith 1979 1984, in Martin 1996). They particularly like figs (Frith 1979).
Compétition: The common myna competes aggressively with native wildlife for nesting hollows. Hollows are in short supply over much of Australia because of clearing for agriculture (Tidemann 2007c). Australian woodlands supports a wide range of hole-nesting bird and mammal species, particularly parrots and kingfishers. Studies in Australia and some oceanic islands suggest that mynas can reduce the breeding success of several hole-nesting species, particularly parrots. Many of these species are classified as threatened. Many observations have also been made in which species have been recorded being usurped from nest holes by mynas. Species affected include the laughing kookaburra (Decelo gigas), sacred kingfisher (Todiramphus sanctus), galah (Cacatua roseicapilla), eastern rosella or pale-headed rosella (Platycelus eximius), and crimson rosella (Playcelus elegans). Several small mammal species such as the sugar glider (Petaurus breviceps), are also evicted from hollows by mynas.
Nuisance pour les personnes: In urban areas common mynas form large communal roosts that may become an annoyance to residents
due to noise and faecal matter (Kang et al. 1990, in Martin 1996) and they have potential to spread disease (Long 1981, Crawford 1990, in Martin 1996). Mynas become quite fearless of people if they are not hassled and can be a problem in outdoor eating areas by stealing food off people’s plates (Tidemann 2007c).
Transmission de maladie: Mynas can spread mites and they have the potential to spread disease to people and domestic animals (Tidemann 2007c).
Agricole: In Queensland the bird is a pest of figs (Massam 2001).
Western Australia (Australia)
Agricole: The common myna is a moderate pest of agriculture causing damage to orchard fruits such as fig, apple, pear, strawberry, guava, mango and grape. It also damages standing cereal crops including maize, wheat and rice (Government of Western Australia Undated).
Compétition: The common myna aggressively competes for nest hollows and food, adversely aff ecting the breeding success of other birds and hollow-nesting mammals. It has been observed attacking terns on islands as well as taking the eggs of other seabirds, possibly interfering with those birds’ breeding and general behaviour.
Transmission de maladie: The common myna is also known to spread avian malaria to other birds
Menace pour les espèces en danger: The common myna competes with the IUCN Red List Vulnerable superb parrot (Polytelis swainsonii), the South Australian glossy black cockatoo (subspecies Calyptorhynchus lathami halmaturinus), which is listed as endangered under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and South Australia National Parks and Wildlife Act 1972, and brown treecreeper (eastern subspecies Climacteris picumnus victoriae) which is listed as vulnerable under the Threatened Species Conservation Act 1995 (CIMAG Undated).
The common myna eats the following threatened insects: the golden sun moth (Synemon plana), which is listed as threatened under the Flora and Fauna Guarantee Act 1988 (Vic) and as endangered under the Nature Conservation Act 1980 (ACT) and the Threatened Species Conservation Act 1995 (NSW), and the perunga grasshopper (Perunga ochracea), which is listed as vulnerable under the Nature Conservation Act 1980 (ACT) (CIMAG Undated).
Réduction de la biodiversité indigène: Recent work examined the potential of the introduced sturnids, the common myna and the common starling (Sturnus vulgaris), to affect reproductive performance of two native hollow-nesting parrots in the Canberra region (Pell & Tidemann 1997). The experimental study was undertaken using artificial nest boxes at the Red Hill Nature Park and Oakey Hill Nature Park reserves (Tidemann and Pell 1997). This study demonstrated that mynas were more aggressive than all other hole-nesting species present including the eastern rosella (Platycelus eximius), crimson rosella (Playcelus elegans) and common starling. During this study, it became apparent that the common myna, in particular, could have potentially adverse effects on breeding success in native parrots (Pell & Tidemann 1997).
Anecdotal evidence and observations also suggest the common myna could negatively affect parrots, rosellas, lorikeets, kookaburras, dollarbirds, possums and sugar gliders (CIMAG Undated).
Mangaia Is. (Cook Islands)
Menace pour les espèces en danger: Mynas may 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 IUCN Red List Vulnerable Mangaia kingfisher (Todiramphus ruficollaris). 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.
Agricole: The Cook Islands Biodiversity website describes the common myna as a serious invasive and agricultural pest.
Compétition: Mynas are great exploiters of local food sources. The seashore along the main street in Suva attracts hundreds of mynas at low tide. They scavenge on worms, molluscs, crustaceans and other seafood that has been washed up on the mud flats (Stoner 1923). This may limit food for native seabirds.
Nuisance pour les personnes: 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.
Prédation: The common myna consumes the eggs and young of terns (Sterna spp.) and noddies (Anous spp.) (Pernetta & Watling 1978). Agonistic behaviour has also been reported between red-vented bulbuls (Pycnonotus cafer) and the common myna and the jungle myna (Acridotheres fuscus).
Transmission de maladie: Mynas in Fiji have been identified as carrying owl flies, biting lice, Oxyspirrura thread worms and round worm (Stoner 1923). Populations of the bird may provide reservoirs of a disease that affects native birds, while themselves remaining largely unaffected.
Interaction avec d'autres espèces envahissantes: Acridotheres tristis est suspecté de contribuer à la dissémination de plantes exotiques envahissantes en consommant leurs fruits.
Menace pour les espèces en danger: Acridotheres tristis est soupçonné d'avoir contribué à l'exclusion de certaines espèces endémiques des Marquises comme la Rousserolle des Marquises (Acrocephalus caffer mendanae) ou le Ptilope de Petit Thouars (Ptilinopus dupetitthouarsii). Il représente une menace importante pour le Monarque de Tahiti, espèce classée en danger critique d’extinction par l’UICN (voir Pomarea nigrar dans la Liste rouge de l'UICN des espèces menacées) (Blanvillain et al., 2003).
Prédation: Acridotheres tristis est capable de consommer les œufs ou les jeunes d'oiseaux indigènes comme ceux du Salangane de la Société (Collocalia leucocephalus) (Holyoak and Thibault 1984, Seitre and Seitre 1992).
Moorea Is. (French Polynesia)
Prédation: 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).
Réduction de la biodiversité indigène: Mynas may have contributed to the decline of the long-billed reed warbler (Holyoak and Thibault 1984)
Tahiti Is. (French Polynesia)
Agricole: Mynas eat and damage cultivated fruits in Tahiti (Holyoak 1974).
Autre: The common myna may have contributed to the decline of the long-billed reed warbler (Holyoak and Thibault 1984).
Menace pour les espèces en danger: The IUCN Red List Critically Endangered Tahiti monarch (Pomarea nigra) initiates aggressive encounters with mynas to defend nest sites (Blanvillain et al. 1999) and in one study Tahitian flycatchers failed to raise chicks in areas where more mynas (and bulbuls) were present. It is not clear whether the poor response of the Tahiti monarch to management is due to less effective rat control or whether mynas, bulbuls, and possibly other species, are indeed having an effect. Mynas may be a nest predator of the Tahiti monarch. In addition, the very fragmented nature of forest habitat in Tahiti means that mynas have ready access to the main breeding areas of Tahiti monarchs (Pierce and Blanvillain 2000). In most cases there is considerable difficulty in separating the effects of mammalian predators from those of mynas and other avian predators, such as in Tahiti (Blanvillain et al. 1999).
Réduction de la biodiversité indigène: Mynas prey on the eggs and young of swiftlets (Collocalia spp.) including the Tahiti swiftlet (Collocalia leucocephalus) (Holyoak and Thibault 1984, Seitre and Seitre 1992).
Compétition: In Israel, common mynas have shown aggressive behaviour towards Syrian woodpeckers (Dendrocopos syriacus) (Holzapfel et al. 2006, in Markula Hannan-Jones & Csurhes 2009).
Nuisance pour les personnes: In Israel, common myna nest sites have been found in palm trees, woodpecker holes, traffic lights, electricity utility poles, and crevices in buildings (Holzapfel et al. 2006, in Markula Hannan-Jones & Csurhes 2009).
Tel Aviv (Israel)
Compétition: Mynas were observed taking over an active nest of a Syrian woodpecker (Dendrocopus syriacus).
Inconnu: 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.
Nuisance pour les personnes: 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).
Grand Terre Is. (New Caledonia) (New Caledonia (Nouvelle Calédonie))
Compétition: Acridotheres tristis est suspecté d'entrer en compétition avec des espèces locales d'oiseaux pour les ressources alimentaires et les sites de nidification (Pascal et al., 2006).
Interaction avec d'autres espèces envahissantes: Acridotheres tristis aurait un rôle essentiel dans l'extension massive du Lantana camara (Virot, 1956 in Gargominy et al., 1996)
Autre: Common myna nests have been found in nest-boxes established for saddlebacks (Philesturnus carunculatus) on the Hen and Chickens island group, although no displacement has been observed (R. Pierce Pers. Obs., 2005). Breeding success of the common starling (Sturnus vulgaris) may be reduced to very low levels because of destruction of nests by mynas (Wilson 1979).
Compétition: Hole-nesting species displaced by common myna from nests in New Zealand include the sacred kingfisher (Todiramphus sanctus) (several records) and the introduced eastern rosella, some of which have involved loss of eggs or chicks (Moon 1991, CSN 1994).
Prédation: Mynas are omnivorous and anecdotal observations suggest that they frequently kill reptiles and birds' eggs and young. Most recorded bird deaths are from New Zealand and they include eggs and nestlings of the New Zealand wood pigeon (Hemiphaga novaeseelandiae), sacred kingfisher (Todiramphus sanctus), tui (Prosthemadera novaeseelandiae), grey warbler (Gerygone igata) and fantail (Rhipidura fuliginosa) (CSN 1972: McKenzie 1979, Heather and Robertson 2000).
Further study is needed, in different situations, to determine whether mynas are a significant factor in species recovery. For example, Armstrong and colleagues (2000) suspected that mynas were the key avian predator species responsible for significant nest failure of North Island robins (Petroica australis longipes) in secondary forest on Tiritiri Matangi Island, New Zealand. It is also suspected that mynas affect the nesting success of red-crowned kakariki (Cyanoramphus noveseelandiae) on northern New Zealand islands and at sites on the adjacent mainland where control of mammalian predators is underway.
Moturoa Is. (New Zealand)
Réduction de la biodiversité indigène: During myna control undertaken on Moturoa Island, Bay of Islands, New Zealand, Tindall (1996) documented increases in the numbers of many small indigenous birds including tui (Prosthemadera novaeseelandiae), fantail (Rhipidura fuliginosa), grey warbler (Gerygone igata), silvereye (Zosterops lateralis), and welcome swallow (Hirundo neoxena), along with introduced species such as blackbird (Turdus merula), chaffinch (Fringilla coelebs), and common starling (Sturnus vulgaris).
Reunion (La Réunion)
Interaction avec d'autres espèces envahissantes: Acridotheres tristis is suspected of contributing to the spread of invasive alien plants by consuming their fruit.
Reunion (La Réunion)
Agricole: Mynas cause damage to fruits and negatively affect crop production (Philippe Clergeau. Pers. Comm. 2005).
Interaction avec d'autres espèces envahissantes: Concerns have been raised on the role of mynas in the dissemination of exotic weeds (Philippe Clergeau. Pers. Comm. 2005). The common myna is suspected of contributing to the spread of invasive alien plants by consuming and dispersing their fruit and seeds (Probst 1997).
Ascension Is. (Saint Helena)
Prédation: 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.
Prédation: The population of sooty terns Onychoprion fuscata breeding on Ascension Island in the Atlantic Ocean was monitored over 17 years (1990 to 2007). A program of feral cat eradication commenced in 2001 and the island was considered cat-free in 2004. Hughes Martin & Reynolds (2008) report on the abundance of sooty terns and black rats (Rattus rattus) before and after cat eradication. The sooty tern breeding population in the 1990s averaged 368 000 and cats were killing terns at an average rate of 33 adults per night. Following cat eradication, adult terns are no longer predated. However, egg predation by both rats and common mynas continued with mynas destroying more eggs than rats. Mynas were not previously considered a threat but Hughes Martin and Reynolds (2008) found that they are a major predator of sooty tern eggs and were the cause of 25% of egg losses.
Réduction de la biodiversité indigène: Feral populations of cats, rats and mynas apparently lead to a decline in seabird populations (Stonehouse 1962, in Hughes Martin & Reynolds 2008).
Compétition: 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 avec d'autres espèces envahissantes: 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).
Prédation: 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).
Menace pour les espèces en danger: Studies in some oceanic islands, particularly the Seychelles, suggest that mynas can reduce the breeding success of several hole-nesting species, especially parrots and the IUCN Red List Endangered Seychelles magpie robin (Copsychus sechellarum). Tree hole nests and hollows may be a limiting factor for some threatened species on oceanic islands such as the Seychelles (Millet et al. 2004).
Fregate Is. (Seychelles)
Menace pour les espèces en danger: The common myna is considered a serious threat (through predation and competition) to the endemic and 'Endangered (EN)' Seychelles magpie robin (see Copsychus sechellarum in IUCN Red List of Threatened Species) on Fregate Island. The population of the magpie robin in 2006 was 178 birds (including 82 on Frégate, 46 on Cousin, 32 on Cousine and 18 on Aride) (BirdLife International 2008).
Réduction de la biodiversité indigène: The common myna is considered a serious threat (through predation and competition) to the endemic and 'Endangered (EN)' Seychelles magpie robin (see Copsychus sechellarum in IUCN Red List of Threatened Species) on Fregate Island. The population of the magpie robin in 2006 was 178 birds (including 82 on Frégate, 46 on Cousin, 32 on Cousine and 18 on Aride) (BirdLife International 2008).
Encrassement: Large communal roosts of mynas in urban environments cause many problems. The common myna increases noise pollution and fouls the environment by depositing droppings and other debris (Yap et al.. 2002, in Lim Sodhi Brook and Soh 2003).
Nuisance pour les personnes: In high densities mynas are a human nuisance.
Réduction de la biodiversité indigène: In Singapore the decline of the native hole-nesting oriental magpie robin (Copsychus saularis) may be due to the exotic mynas (Huong & Sodhi 1997, in Lim Sodhi Brook and Soh 2003).
Réduction de la biodiversité indigène: The adverse effects of introduced common mynas on indigenous biodiversity in South Africa have not been well documented. Interspecific aggression between common mynas and indigenous urban birds, for example, the laughing dove (Streptopelia senegalensis), crested barbet (Trachyphonus vaillantii), red-throated wryneck (Jynx ruficollis), Karoo thrush (Turdus smithi), Cape sparrow (Passer melanurus) and southern masked-weaver (Ploceus velatus) are occasionally witnessed, but potential displacement of indigenous species is believed to be limited to the local scale (R. Geyser, K. Hattingh, Pers. Comm., D.S.P. Pers. Obs., in Peacock Van Renburg & Robertson 2007).
Elsewhere, mynas are criticised for competing with indigenous birds and mammals for nesting cavities, which has been shown to be a limiting resource for many species throughout the world. Predation of chicks and eggs, and direct attacks on adults of indigenous and other alien birds, have been reported in some areas, particularly island ecosystems.
Hawaii (Hawai‘i) Is. (United States (USA))
Interaction avec d'autres espèces envahissantes: 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 avec d'autres espèces envahissantes: The common myna consumes the berries and disperses the seeds of the agricultural and environmental weed lantana (Lantana camara), contributing to its spread in the Hawaiian islands (Lever 1987). Native birds do not generally consume lantana berries and the common myna is presumably altering local ecosystems by its frugivorous behaviour.
Prédation: Byrd (1979) found that common mynas are significant consumers of the eggs of wedge-tailed shearwaters (Puffinus pacificus) in the Hawaiian Islands. In a study on Kauai the author found that 23% of shearwater eggs were destroyed by the common myna (Lever 1987).