Age and sex-independent comparisons of morphological measurements.
A method is proposed for the comparison of morphological parameters that compensates for sex and age effects. An index is calculated for individual animals, from which percentage differences in size that are independent of age-sex classes can be postulated for specific environmental effects. The method is appropriate for any data set that has a sufficiently broad age range to enable an accurate fitting of a growth curve, and thus overcomes the problem of using only fully mature animals for environmental comparisons. Besides detecting general size effects, the technique enables interpretation of changes at specific phases of the growth curve when more elaborate techniques for doing this are not appropriate. An hypothesised difference in size is confirmed between two fallow deer populations, living at different densities with different preferred food availability. The method is seen as being generally applicable, its appropriateness for any particular data set can be easily gauged, and the method itself is simple to apply.