Scaly-breasted Munia

The scaly-breasted munia is about 11–12 centimetres (4.3–4.7 in) long and weighs 12–16 grams (0.026–0.035 lb). 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 (Lonchura malacca) across the Asian and island populations and the black-throated munia (Lonchura kelaarti) in parts of India or Sri Lanka.

Scaly-breasted munias are found in a range of habitats 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 (1.6 mi), and in the Nilgiris, where they are found at altitudes up to 2,100 m (6,900 ft) 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 colonise new areas nearby. Escaped cagebirds established in the wild and such populations have been recorded in the West Indies (Puerto Rico since 1971), Hawaii (since 1883), Japan and southern United States, mainly in Florida and California. In Oahu, Hawaii, they compete for habitats with the tricoloured munia and tend to be rare where this competitor is present. The species has been introduced to other parts of the world due to its popularity as a cage bird and populations have established in the wild.

The scaly-breasted munia feeds mainly on grass seeds, small berries such as those of Lantana, and insects. Although the bill is suited for crushing small grains, they do not show lateral movements of the lower mandible that e.g. greenfinches show, which help 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 behaviour and physiology. Feeding behaviour can be predicted by the optimal foraging theory, where animals minimise time and energy spent to maximise food intake. This theory has been tested by studying the strategies used by scaly-breasted munias to increase their feeding efficacy.

Flock size tradeoffs. Studies on foraging have examined the effect of group size in reducing time spent on predator vigilance, thereby increasing feeding efficiency. According to the "many-eyes" hypothesis, a reduction in the individual time spent on vigilance against threats in larger groups allows for more time to be spent on searching for food and feeding. Vigilance is greatest among solitary individuals and reduces as the group size increases to about four. …