Current Ornithology

Volume 13 of the series Current Ornithology pp 67-135

Assessing Body Condition in Birds

  • Margaret E. BrownAffiliated withDepartment of Biological Sciences, Purdue University

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Important biological concepts typically have many definitions. Body condition is no exception; it is a multi-level phenomenon that can be defined either conceptually or operationally. Although at this time there is no clear consensus on the definition for body condition, conceptually, the term in many cases describes the degree to which an organism’s physiological state influences its performance (i.e., production, activity, or response to environmental conditions). Operational definitions for condition typically are based on some aspect of body composition (e.g., levels of nutrient stores or indirect indicators of such levels). Despite these complexities, numerous published studies have documented the effect of a bird’s nutritional status on some aspect of Darwinian fitness. The primary goals of this chapter are to describe the available methods of assessing condition, evaluate their accuracy and utility, illustrate how these methods have been applied, and clarify how they satisfy operational and conceptual definitions of body condition. The result will be to provide a primer for researchers interested in obtaining condition estimates, as well as for those wishing to improve upon existing methods.