Diurnal and seasonal variation in liver glycogen and fat in relation to metabolic status of liver and m. pectoralis in the migratory starling, Sturnus roseus, wintering in India.

1. Levels of glycogen and fat in the liver showed a diurnal difference, being higher at dusk than at dawn during the post- and premigratory periods. 2. Fat level increased by at least more than double from its lowest in the postmigratory period (August) to highest towards migration time (21-30 April) at both dawn as well as dusk. 3. With the steady increase in liver fat, there was a gradual decrease in liver glycogen up to about the middle of April and a slight increase thereafter. 4. RQ values obtained for liver and pectoralis muscle slices in vitro at postmigration (August) indicated lipid utilization. Those for the premigratory period indicated hyperlipogenesis, while towards migration time the values denoted carbohydrate catabolism and sparing of lipid.