Growth curves of wild Mallard, based on functional analysis of capture–recapture data

We propose a functional data analysis (FDA) approach based on capture–recapture data to fit growth curves to wild Mallard Anas platyrhynchos. For this purpose, growth curves are provided from weight measurements through smoothing based on a suitable expansion in terms of B-splines. In dealing with wild young birds the unknown date of hatching and the small number of recaptures represent challenging problems. Our results suggest that the size at fledging of wild Mallards is not the adult size; the adult weight is reached at 70–80 days. We have not noted weight losses in fledging young and so the metabolic cost of fledging does not seem to be high. Our statistical approach offers a valid way to quantify the growth of precocial birds.