Meeting Abstract

P1.147  Sunday, Jan. 4  Water availability is not a bottle-neck to rebuilding fat stores in insect-eating, migrating blackcaps MIZRAHY, Ortal*; BAUCHINGER, Ulf; PINSHOW, Berry; Ben-Gurion University ; Ben-Gurion University ; Ben-Gurion University ortalmi@bgu.ac.il

Migrating birds stopover to rebuild lost tissue, and access to drinking water positively affects fat accumulation. Before fat is accrued, birds must rebuild their digestive tracts (GIT). We used 30 freshly caught, migrating blackcaps (Sylvia atricapilla) to test the prediction that after a simulated in-flight starvation period the rebuilding of the GIT is faster in birds with access to drinking water than without. Ten birds were randomly assigned to each of three groups receiving: water ad libitum, 30 min access to water per day, or no water. All three groups were fed mealworms ad libitum for the 6-day experiment. Mean daily water intake was significantly different among the groups (5.42±1.0 g; 0.81±0.1 g and 0 g; Holm-Sidak test, F=165, p<0.001). Despite this, there were no differences in daily food intake (ANOVA F_(2,28)=0.23, NS). Furthermore, in all groups, mean food intake almost doubled from day 1 to day 2, remained high until day 4, and declined on days 5 and 6. Body mass in all groups increased continuously from day 1 to day 6 (15.5±1.0 g to 19.4±1.2 g, ANOVA F_(1,58)=190.76, p<0.0001) and did not change on day 7 (19.4±1.2 g to 19.6±1.3 g, ANOVA F_(1,58)=0.28, NS), suggesting that tissue replacement was complete. Visual fat score increased similarly in all three groups (from 0±0.45 to 3±1.2, ANOVA F_(2,28)=0.47, NS). The data did not support our prediction in that there were no apparent differences in body mass and fat score between the groups. Although preformed and metabolic water gained through eating mealworms is apparently sufficient for blackcaps to rebuild their digestive organs and fat stores, given access to water the birds drink prodigiously, perhaps allowing more time for activity.