Scaly-breasted Munia

Appearance

The scaly-breasted munia is about 11–12 centimetres long and weighs 12–16 grams. The adult has a stubby dark bill typical of grain eating birds, brown upperparts and a dark brown head. The underparts are white with dark scale markings. The sexes are similar, although males have darker markings on the underside and a darker throat than females.

Immature birds have pale brown upperparts, lack the dark head found in adults, and have uniform buff underparts that can be confused with juveniles of other munia species such as the tricoloured munia across the Asian and island populations and the black-throated munia in parts of India or Sri Lanka. Populations within their wide distribution range show variations in plumage color and size.

Along with other Estrildines, these species are thought to have originated in Asia. The species been introduced to other parts of the world due to its popularity as a cage bird and populations have established in the wild.

Naming

A species of the genus "Lonchura", it was formally described and named by Carl Linnaeus in 1758. Its name is based on the distinct scale-like feather markings on the breast and belly.

Distribution

Scaly-breasted munias are found in a range of habitas but are usually close to water and grassland. In India, they are especially common in paddy fields where they are considered a minor pest on account of their feeding on grain.

They are found mainly on the plains, but can be observed in the foothills of the Himalayas, in which they may be present at altitudes near 2,500 m, and in the Nilgiris, where they are found at altitudes up to 2,100 m during the summer.

In Pakistan, they are restricted to a narrow region from Swat in the west to Lahore, avoiding the desert zone, and then occurring again in India east of an area between Ludhiana and Mount Abu. The species has also been observed in Kashmir, though this is rare.

Outside their native range, escaped birds frequently establish themselves in areas with a suitable climate and can then colonize new areas nearby. Escaped cage-birds established in the wild and such populations have been recorded in the West Indies, Hawaii, Australia, Japan and southern United States mainly in Florida and California. In Oahu, Hawaii, they compete for habitats with the tricolored munia and tend to be rare where this competitor is present.

Status

"Lonchura punctulata" is an abundant species and classified as "Least Concern" by the International Union for Conservation of Nature. The species occupies an extremely large range, and its population, while still unquantified, is large and stable. The scaly-breasted munia is not globally threatened and is common to very common throughout most of its range. However, some populations, such as those in the Lesser Sunda Islands are scarce.

In many areas it is regarded as an agricultural pest, feeding in large flocks on cultivated cereals such as rice. In Southeast Asia, the scaly-breasted munia is trapped in large numbers for Buddhist ceremonies, but most birds are later released.

Behavior

Scaly-breasted munias form flocks of as many as 100 birds. Individuals communicate with calls that include a short whistle, variations of "kitty-kitty-kitty", and a sharp chipping alarm note. They sometimes flick their tails and wings vertically or horizontally while hopping about. The tail flicking motion may have evolved from a locomotory intention movement. The exaggerated version of the tail flicking movement may have undergone ritualization. As a social signal, tail flicking in several other species acts as a signal indicating the intent to fly and helps keep flocks together.

When roosting communally, scaly-breasted munia sit side-by-side in close contact with each other. The outermost bird often jostles towards the center. Birds in a flock sometimes preen each other, with the soliciting bird usually showing its chin. Allopreening is usually limited to the face and neck. The scaly-breasted munia is rarely hostile but birds will sometimes quarrel without any ritualized posturing.

Reproduction

The breeding season is during the summer rainy season but can vary. Laboratory studies have found that long day illumination and high humidity trigger gonadal growth. The song of the male is very soft but complex and variable, audible only at close range. This song described as a jingle consists of a series of high notes followed by a croaky rattle and ending in a slurred whistle. When singing the male sits in what is called the "slope" posture—erect with the head feathers raised.

There are two types of slope posture, a pre-copulatory one and an ordinary one. The pre-copulatory behavior of scaly-breasted munia includes a sequence of actions. The first involves either the male or female playing with nest-material. As soon as a bird has arranged the nest material in its bill, it begins to fly around in a zig-zag path. Once a bird lands close to its partner, the male bends towards the female and wipes its bill. The male then sings with movements of the body. The female invites mounting with tail quivering.

The nest is a large domed structure loosely woven from blades of grass, bamboo or other leaves with a side entrance and is placed in a tree or under the eaves of a house. A study in southern India found the preferred nesting trees to be "Toddalia asiatica", "Gymnosporia montana" and "Acacia chundra", especially short and bushy ones in areas with low canopy cover. The nest opening is located to face downwind of the most frequent wind direction. In northern India, they preferred isolated "Acacia nilotica" in non-urban areas but used "Thuja orientalis" and "Polyalthia longifolia" in urban gardens.

Scaly-breasted munia clutch usually contain 4 to 6 eggs, but can contain up to 10. Both sexes build the nest and incubate the eggs, which hatch in 10 to 16 days. Juveniles typically fledge in three weeks. Both sexes may reach sexual maturity as early as 7 months after birth in captivity.better source needed In the wild, however, since maturation may be impacted by variable daylight and humidity, both sexes can take between 12 and 18 months to reach sexual maturity depending on the time of year. Scaly-breasted munias have a typical life expectancy of 6 to 8 years.

Food

The scaly-breasted munia feeds mainly on seeds but also eats small berries such as those of "Lantana". Although the bill is suited for crushing small grains, they do not show lateral movements of the lower mandible which help European greenfinches in dehusking seeds. Like some other munias, they may also feed on algae, a rich protein source, prior to the breeding season.

The ease of maintaining these birds in captivity has made them popular for studying behavior and physiology. Feeding behavior can be predicted by the optimal foraging theory, where animals minimize time and energy spent to maximize food intake. This theory has been tested by studying the strategies used by scaly-breasted munias to increase their feeding efficacy.