Gary L. Krapu Kenneth J. Reinecke Dennis G. Jorde Douglas H. Johnson 1985 <p>A Lipid Index, the ratio of fat to fat-free dry weight, is proposed as a measure of fat stores in birds. The estimation of the index from field measurements of live birds is illustrated with data on the sandhill crane (<i>Grus canadensis)</i> and greater white-fronted goose (<i>Anser</i> <i>albifrons</i>). Of the various methods of assessing fat stores, lipid extraction is the most accurate but also the most involved. Water extraction is a simpler laboratory method that provides a good index to fat and can be calibrated to serve as an estimator. Body weight itself is often inadequate as a condition index, but scaling by morphological measurements can markedly improve its value.</p> application/pdf 10.2307/3801673 en Wiley An evaluation of condition indices for birds article