Meeting Abstract

S10.6  Friday, Jan. 7  The effects of dietary protein and water availability on mass gain in passerine birds refueling during migration. PINSHOW, B*; AAMIDOR, S; MIZRAHY, O; MCWILLIAMS, SR; BAUCHINGER, U; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; University of Rhode Island; University of Rhode Island pinshow@bgu.ac.il

We tested the hypothesis that dietary protein and water availability influence refueling in blackcaps (Sylvia atricapilla ) during migratory stopover by depriving freshly caught birds of food for 2 d, to simulate in-flight starvation, and re-feeding them for 6 d in two trials: 1) In spring and autumn, birds were fed one of two isocaloric diets containing either 3% or 20% protein; and 2a) birds were offered mealworms (~60% water) ad lib., and either water ad lib., 0.5 h/d access to water, or no water; 2b) birds were offered an insect-based diet (~33% water) ad lib., and either water ad lib., or 0.5 h access to water twice a day. Using one and two way RM ANOVA, we found no differences between the protein diet groups in rate of increase in body mass (m_b) in either season, and no interactions between groups and rate of accumulation of either fat (m_f) or lean mass (m_l). However, in spring m_f and m_l were higher than in autumn. Furthermore, food intake increased faster in birds on 3% protein, and in all birds in spring. The birds’ water intake was significantly different between water availability regimes in both diet groups. The rates of change in m_b, m_l and m_f were not affected by water availability in birds fed mealworms, but were positively affected in birds fed the insect-based diet. We conclude that the rate of refueling in blackcaps is not necessarily limited by dietary protein (that may be compensated for by hyperphagia), but is positively correlated with drinking water availability when food water content is low.