Daily rhythmicity in the body weight of Spotted munia(Lonchura punctulata):Effect of food intake and light/dark cycles

Abstract

A distinct daily cyclicity in the body weight of Spotted munia, a diurnal waxbill (fam. Estrildidae), was established. The results indicated that the cycle persists even after: (a) the removal of food contents; (b) fixing the food intake to constant intervals. No parallelism was found in daily feeding pattern and daily weight gain. The cyclicity is therefore not due to food intake per se but may be a physiological phenomenon. The body weight continued to cycle in LL and the cycles of different animals were desynchronized indicating an endogenous circadian nature. The cycles were entrainable to LD 12:12 and ahemeral light/dark cycles LD 8:8, LD 6:6. Since the body weight in Spotted munia exhibits a distinct annual/circannual rhythmicity, this bird may be an ideal model for the study of interaction, if any, between the daily/circadian and annual/circannual rhythms.