SREL Reprint #2719

Condition indices for wintering American wigeon

Travis L. DeVault1, Olin E. Rhodes, Jr.1, and Loren M. Smith2

1Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907, USA
2Department of Range, Wildlife, and Fisheries Management, Texas Tech University, Lubbock, TX 79409, USA

Abstract: Condition indices that provide reliable estimates of body condition are valuable tools in waterfowl management. We evaluated the ability of condition indices to predict total body fat and protein for hunter-killed American wigeon (Anas americana) wintering on the Southern High Plains of Texas, USA. Six hundred and forty-two wigeon were collected from 1 October 1988 to 15 March 1989 and processed in the laboratory to determine mean values of carcass components including lipids, ash, and ash-free lean dry mass (protein). In regression equations for various sex and age groups, mass of omental fat deposits was the single best predictor of total body fat (R2 =0.82 to 0.90), although addition of body mass or carcass mass to the equations somewhat improved accuracy of the models (up to R2 =0.93). Protein was not as accurately predicted by measured variables, although equations using the same variables that accurately predicted total body fat (carcass mass or body mass+omental fat mass) provided R2 values up to 0.53 for protein. Total body fat and, to a lesser extent, protein can be estimated reliably for wintering American wigeons using easily obtained measurements of dead birds.

Keywords: American wigeon, Anas americana, body reserves, condition index, Texas, waterfowl

SREL Reprint #2719

DeVault, T. L., O. E. Rhodes, Jr., and L. M. Smith. 2003. Condition indices for wintering American wigeon. Wildlife Society Bulletin 31:1132-1137.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).