Sugar Preference and Apparent Sugar Assimilation in the Red Lory

Abstract

The red lory, Eos bornea (family Psittacidae), was tested to determine its preference for hexose sugars or sucrose. The indices of sugar preference used were (a) number of visits to feeders, (b) time spent feeding and (c) volume of solution drunk. The red lory showed no preference for a specific sugar when offered a choice of glucose, fructose and sucrose at a concentration of 0.73 mol L-1. However, when concentration of the sugars was 0.25 mol L-1, the red lory showed no significant preference by the number of visits but it showed a preference for sucrose by increasing the time spent feeding and the volume drunk. The choice made at lower concentrations may reflect preference for the sugar with the highest energy reward. Birds were fed 0.25 mol L-1 sucrose, 0.73 mol L-1 sucrose and 0.73 mol L-1 glucose in separate laboratory trials to determine the concentration of sugar in the excreta. The red lory was efficient at energy extraction, excreting less than 1% sucrose equivalent, irrespective of the initial sugar concentration of each diet.