Morphological Prediction of Body Condition in Maned Ducks

Abstract

Best-fit regression equations for estimating body-fat levels from morphological measurements of maned ducks (Chenonetta jubata) were developed. The cube of [body weight/(sternum x tarsus x bill length)] plus the square of skinfold thickness was the best predictor of body fat in females (r*2=0.81). The cube of (body weight x skinfold thickness) was the best predictor in males (r*2=0.75). These regression equations accurately estimated fat level in all seasons except females in winter, when estimated values were significantly higher (paired t test, P<0.02) by 18% than actual levels. Body weight alone predicted protein content well in males (r*2=0.81) and less well in females (r*2= 0.61). These equations enable long-term and relatively cheap monitoring of body condition in trapped maned ducks.