Diet and Breeding Seasonality among a Population of Sharp-Tailed Munias, Lonchura striata, in Malaysia

Abstract

Abstract From April 1975 through March 1977, the food habits and breeding seasonality of a population of Sharp-tailed Munias (Lonchura striata) were studied in northwestern peninsular Malaysia. The abundance of munias on the study area varied in accordance with the 6-month rice-growing cycle there. The population peaked in March and September when juvenile birds were most numerous and when rice was most plentiful. Field observations and stomach analyses showed that the munias ate rice and the green filamentous alga, Spirogyra, almost exclusively. The primary periods of algae eating occurred in January and June-August, coinciding with the munias' two peak periods of reproductive activity, as determined by gonadal examination. Apparently munias on the study area ate Spirogyra as a source of protein to enable them to become physiologically ready for breeding, much as othe tropical bird species eat insects. Thus, unlike other species, Sharp-tailed Munias' breeding seasonality is determined by manmade cycles of rice cultivation rather than by natural cycles of rain and insect abundance.