Energy for the road: Influence of carbohydrate and water availability on fueling processes in autumn-migrating passerines

Abstract

ABSTRACT Lipids stored subcutaneously serve as the main energy source for long-distance bird migration. The 2 major inputs of such lipids are dietary fats and de novo synthesis of fatty acids from acetyl-CoA derived from non-lipid sources, including ingested carbohydrates. Remarkably, relatively little is known about the specific roles of dietary fats and carbohydrates in fat-deposition processes of migratory passerines. We report the results of a large-scale field experiment complemented by a captivity experiment, aimed at testing the effects of the availability of simple carbohydrates and water on fuel deposition rates of autumn-migrating passerines in the northern Negev of Israel. We found that in the main study site, Ein Rimon, where birds mostly consume fat-rich Atlantic pistachio (Pistacia atlantica) fruits, access to both water and sucrose solution resulted in faster body mass gain. Similar patterns were evident among captive Eurasian Blackcaps (Sylvia atricapilla) subjected to the same nutritional...