“Violent battles often erupt between occupants of nesting sites and the couple that wish to evict them. Each partner grapples with its opposite number and contestants drop to the ground secured in each other's claws. Bills are jabbed ruthlessly at the opponent. Finally, the defeated couple leaves to search for another site.” - Common Myna fact-sheet, Australian Museum.
The Indian myna (Acridotheres tristis, also known as common myna), belongs to the family Sturnidae and is distributed across Asia. Birds in this family are commonly known as starlings - medium-sized perching birds with a wide repertoire of calls that form large social groups. Some other starlings found in India are the hill myna, jungle myna, Brahminy starling, pied starling and the rosy starling (a winter migrant).
Mynas are gregarious birds, where tens to hundreds of individuals roost throughout the year, often with other species such as crows and rose-ringed parakeets. Such gatherings of birds, which sleep together in the same place, are not incidental as they are seen even when alternate roosting sites are available. Roosting behaviour is commonly seen in birds found in open habitats and those foraging in flocks. It might help them share information about food resources or protect them against predators.
Among the starlings in India, the common hill myna (Gracula religiosa) has the widest call repertoire. They have four basic call types and an individual may have anywhere from five to twelve patterns of vocalisations. They learn these as they are growing into an adult, influenced by the calls of other individuals around them. Common hill mynas can distinguish between individuals based on their calls even when the call types are the same. Their vocal repertoires vary with distance and different populations can have their own dialects. Due to their wide variety of calls and the ability to mimic sounds in captivity, they are traded as pets threatening their populations in the wild.
The Indian myna was introduced in Australia in the 1860s to control insects and has emerged as a major pest. “The introduction and liberation of exotic birds was practised with considerable assiduity both in Sydney and Melbourne. The legacy of such misguided enthusiasm is seen today in the presence of numerous starlings, sparrows, goldfinches, and other birds that inhabit, for the most part, the settled areas of Australia,” says an article from 1948. Using genetic data, researchers have found that mynas introduced in Melbourne likely arose from a population in Maharashtra, which then invaded New Zealand.
The Indian myna is listed among the world’s hundred worst invasives - species which are introduced outside their native range and cause ecological harm in the new environment. Its introduction is associated with a drop in populations of native birds through competition for nesting sites and breeding territories. They are seen to have aggressive interactions with native bird species around tree cavities that they use as nesting sites. A recent study identified certain genetic variants that are common across multiple invasive populations of the Indian myna. The region of the genome carrying these variants is also thought to be involved in the association of house sparrows with humans and may help these birds adapt to novel diets.
