Determining body fuels of wintering mallards

Measuring body lipids and proteins of wild animals such as mallards is esse ntial to determine the impact of the environment on their body condition. A major difficulty, however, is that biochemical analysis of carcass is tedi ous and therefore cannot be applied at a large scale. The main objective of this study was therefore to find out if simple measurements can be used as indices of total body lipids and proteins. Four classes of lipid and prote in indices, derived on a 'source' group, were defined according to their co mplexity and condition of application (field or laboratory). Accuracy of th e indices was evaluated on an independent group, of which the body composit ion calculated from indices was compared to carcass analysis. In live birds , body mass was an accurate and convenient predictor for both lipid and pro tein masses. If carcasses are available, extensive analysis provides a high er accuracy for body lipids only. This can be simply obtained through multi ple regressions using abdominal fat mass and/or dry body mass. (C) 2000 Aca demie des sciences/Editions scientifiques et medicales Elsevier SAS.