Comparison of condition indices in migratory passerines at a stopover site in coastal Louisiana

Condor
By: , and 

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Abstract

We evaluated the utility of four nondestructive condition indices—body mass, body mass scaled by wing chord length, fat scoring, and total body electrical conductivity method (TOBEC)—as predictors of lipid levels in migrating Wood Thrushes (Hylocichla mustelina), Swainson's Thrushes (Catharus ustulatus), and Summer Tanagers (Piranga rubra). The Red-winged Blackbird (Agelaius phoeniceus), a winter resident, was examined for comparative purposes. In addition, we examined differences among species in relationships of total body lipids and condition indices. Body mass was the best index of lipid levels, explaining 36%-82% of the variation in total body lipids in all four species. The relative contributions of the other indices to the prediction of lipid mass varied among species although TOBEC was selected for inclusion in each regression equation. For two species, equations including TOBEC measurements had lower errors in lipid prediction than equations only using the other nondestructive indices. Errors in lipid prediction were large for all the regression equations based on condition indices. In many cases it will be necessary to develop species-specific equations to predict lipid levels with condition indices.

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Publication type Article
Publication Subtype Journal Article
Title Comparison of condition indices in migratory passerines at a stopover site in coastal Louisiana
Series title Condor
DOI 10.2307/1369029
Volume 97
Issue 2
Year Published 1995
Language English
Publisher Oxford Academic
Contributing office(s) National Wetlands Research Center, Wetland and Aquatic Research Center
Description 7 p.
First page 438
Last page 444
Country United States
State Louisiana
County Cameron Parish
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