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The Mystery Of The Laughing Shadow - Common Mynah

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Acridotheres tristis

The Common Myna or Indian Myna (Acridotheres tristis) also sometimes spelled Mynah, is a member of family Sturnidae, (starlings and mynas) native to Asia. An omnivorous open woodland bird with a strong territorial instinct, the Myna has adapted extremely well to urban environments. The myna has been introduced in many other parts of the world and its distribution range is on the increase. It is a serious threat to the ecosystems of Australia. The Common Myna is an important motif in Indian culture and appears both in Sanskrit and Prakrit literature.

Description

The Common Myna is readily identified by the brown body, black hooded head and the bare yellow patch behind the eye. The bill and legs are bright yellow. There is a white patch on the outer primaries and the wing lining on the underside is white. The sexes are similar and birds are usually seen in pairs.

The Common Myna obeys Gloger's rule in that the birds from northwest India tend to be paler than their darker counterparts in South India.

Morphometry / Morphometry

Body length:23 cms.
Parameter/sex Male Female
Average weight (gms) 109.8 120-138
Wing chord (mm) 138-153 138-147
Bill (mm) 25-30 25-28
Tarsus (mm) 34-42 35-41
Tail (mm) 81-95 79-96

Distribution

It is a species of bird native to Asia with its initial home range spanning from Iran, the entire South Asian subcontinent, including Pakistan, India, Nepal, Bhutan, Bangladesh and Sri Lanka; as well as Turkmenistan, Afghanistan, Kazakhstan, Myanmar, to Malaysia, peninsular Thailand, Indo-China and China.

The Myna has been introduced in many other parts of the world such as Australia, New Zealand, Hawaii, South Africa, and islands in the Indian Ocean (Seychelles, Mauritius, Maldives, Andaman and Nicobar Islands and Lakshadweep archipelago and also in islands of the Atlantic and Pacific Oceans. The range of the Common Myna is increasing to the extent that in 2000 the IUCN Species Survival Commission declared it among the World's 100 worst invasive species. The Myna is one of only three birds in this list of invasive species.[citation needed]

Taxonomy and subspecies

The Common Myna has two subspecies:

Acridotheres tristis tristis (Linnaeus, 1758). Widespread, including Sri Lanka.
A. t. melanosternus Legge, 1879. Endemic to Sri Lanka.
The subspecies melanosternus is darker than the nominate subspecies, has half-black and half-white primary coverts and has a larger yellow cheek-patch.

The type locality of the nominate subspecies is Pondicherry, India.

Behaviour / Vocalisation

Common Myna holding plastic in beak.

Turquoise blue-coloured egg of Common Myna.The calls includes croaks, squawks, chirps, clicks and whistles, and the bird often fluffs its feathers and bobs its head in singing. The Common Myna screeches warnings to its mate or other birds in cases of predators in proximity or when its about to take off flying. Common Mynas are popular as cage birds for their singing and "speaking" abilities. Before sleeping in communal roosts, mynas vocalise in unison which is called as "communal noise".

Breeding

Common Mynas are believed to pair for life. They breed through much of the year depending on the location, building their nest in a hole in a tree or wall. They breed from sea-level to 3000 m in the Himalayas.

The normal clutch size is 4–6 eggs. The average size of the egg is 30.8 x 21.99 mm. The incuation period is 17 to 18 days and fledging period is 22 to 24 days. The Asian Koel is sometimes brood parasitic on this species. Nesting material used by mynas include twigs, roots, tow and rubbish. Mynas have been known to use tissue paper, tin foil and sloughed off snake-skin.

During the breeding season, the daytime activity-time budget of Common Myna in Pune in April to June 1978 has been recorded to comprise the following: nesting activity (42%), scanning the environment (28%), locomotion (12%), feeding (4%), vocalisation (7%) and preening-related activities, interactions and other activities (7%).

The Common Myna uses the nests of woodpeckers, parakeets, etc. and easily takes to nest boxes; it has been recorded evicting the chicks of previously nesting pairs by holding them in the beak and later sometimes not even using the emptied nest boxes. This aggressive behaviour is considered to contribute to its success as an invasive species.

Food and feeding

Like most starlings, the Common Myna is omnivorous. It feeds on insects, arachnids, crustaceans, reptiles, small mammals, seeds, grain and fruits and discarded waste from human habitation. It forages on the ground among grass for insects, and especially for grasshoppers, from which it gets the generic name Acridotheres, "grasshopper hunter". It however feeds on a wide range of insects, mostly picked from the ground. It is a cross-pollinator of flowers such as Salmalia and Erythrina. It walks on the ground with occasional hops and is an opportunistic feeder on the insects disturbed by grazing cattle as well as fired grass fields.

Roosting behaviour

Common Mynas roost communally throughout the year, either in pure or mixed flocks with Jungle Mynas, Rosy Starlings, House Crows, Jungle Crows, Cattle Egrets and Rose-ringed Parakeets and other birds. The roost population can range from less than one hundred to thousands. The time of arrival of Mynas at the roost starts before and ends just after sunset. The mynas depart before sunrise. The time and timespan of arrival and departure, time taken for final settlement at the roost, duration of communal sleep, flock size and population vary seasonally.

The function of communal roosting is to synchronise various social activities, avoid predators, exchange information about food sources.

Communal displays (pre-roosting and post-roosting) comprise of aerial maneuvers which are exhibited in the pre-breeding season (November to March). It is assumed that this behaviour is related to pair formation.

Habitat

This abundant passerine is typically found in open woodland, cultivation and around habitation. Although this is an adaptable species, its population has been decreasing significantly in Singapore and Malaysia (where it is locally called as gembala kerbau, literally 'buffalo shepherd') due to competition with its cousin, the introduced Javan Myna

Urban success

The Common Myna thrives in urban and suburban environments; in Canberra, for instance, 110 Common Mynas were released between 1968 and 1971. By 1991, Common Myna population density in Canberra averaged 15 birds per square kilometer. Only three years later, a second study found an average population density of 75 birds per square kilometer in the same area.

The bird likely owes its success in the urban and suburban settings of Sydney and Canberra to its evolutionary origins; having evolved in the open woodlands of India, the Common Myna is pre-adapted to habitats with tall vertical structures and little to no vegetative ground cover, features characteristic of city streets and urban nature preserves.

The Common Myna (along with European Starlings, House Sparrows, and feral Rock Doves) is a nuisance to city buildings; its nests block gutters and drainpipes, causing water damage to building exteriors.



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