The mean absolute percent error of predicting the fat mass of 40 Rock
Doves (Columba livia) by the cyclopropane absorption method was 11%. A
sensitivity analysis of some of the 15 variables used in computing fa
t mass by the cyclopropane absorption method showed that: (1) cloacal
temperature was a good measure of body-fat temperature, (2) the lipid
solubility coefficient of cyclopropane reported for rats was appropria
te for pigeons, (3) minimum error occurred with an animal density of 1
.08, (4) error was relatively insensitive to a range of reasonable est
imates of body water, and (5) the most accurate method of measuring ch
amber volume was unclear. We list advantages and disadvantages of this
user-unfriendly method and provide recommendations for future users.
This method does not require a calibration based on fat extracted from
dead birds; the accuracy and precision of a system assembled to measu
re the fat mass of live birds can be evaluated with olive oil standard
s. The accuracy of estimating fat mass of a living bird seems to be di
ctated, in large part, by the analytical equipment and procedures used
rather than by the bird.