Total Body Electrical Conductivity (TOBEC) to Estimate Total Body Fat of Free-Living Birds

Traditional methods to determine total body fat are undesirable under many circumstances because they require sacrificing individual birds. Walsberg (1988) recently introduced the total body electrical conductivity (TOBEC) method for total body fat to ecological studies. In this paper we expand on Walsberg's (1988) seminal paper and show that: (1) TOBEC is accurate under a narrow array of body masses, and is therefore appropriate for intraspecific studies; (2) dead birds exhibit significantly different TOBEC than live birds; and (3) the use of metal bands does not affect TOBEC measurements. We conclude that TOBEC provides an accurate estimate of total body fat, that it is preferable to traditional methods because it does not require sacrificing the bird, measurements can be taken quickly in the field, and (most importantly to field ornithologists) body fat can now be tracked through time for individual, free-living birds.