Development of the bridled nailtail wallaby, Onychogalea fraenata, and age estimation of the pouch young

Abstract

Morphological growth and qualitative development of the pouch young of captive Onychogalea fraenata are described from birth to permanent pouch emergence. Intuitively, age is a determining factor of growth and development, which precludes it from being the regressand in regression analysis. Therefore, age prediction can only be achieved by estimating expected growth for various ages and examining the confidence limits to this growth. Age values corresponding to these confidence limits are derived from the growth equations and used as limits for the ages. On the basis of these intervals the reliability of age predictions, for ages measured in different day-based units can be assessed. A statistical method is selected so that a small amount of irregularity in the frequency of measurement can be tolerated, and accounted for, in the model, as well taking into account inter-animal variation in growth parameters.