Effect of food on seasonal response in Indian weaver bird (Ploceus philippinus)

Abstract

We investigated the effect of normal (adlib) and supplementary food on body mass, testes growth, moult and plumage color in Indian weaver birds. Birds intially were kept under natural day length (NDL) and then exposed to short day lengths (8 h light: 16 h darkness) for at least 2 weeks before being subjected to an experimental regime. They were divided into five groups (n=4 each), groups 1 and 2 were held under SDL (Short day length -8L: 16D), groups 3 and 4 were exposed to LDL (Long daylength-16L: 8D) and simultaneously group 5 held under natural day length, served as control. One group of SDL (Group 2) and LDL (group 3) as well as group 5 (NDL) were fed on grain with supplement proteinaceous food and groups 2 and 4 were fed on adlib food (grain) only. Observations on body mass, testis growth, bodymolt and plumage color were recorded bi weekly. A significant change in the body mass under both photoperiodic groups (SDL; group 2 and LDL; group 4), but the testicular growth was noticed on long day lengths (LDL: 16L: 8D) and control (NDL) group. However the supplement food modulated the testes growth, body molt, beak pigmentation and body plumage regeneration. Early feather regeneration was found in supplementary food group under long day length. It is suggested that the supplementary food, affects the timing of the development of secondary sexual characteristics.