Body component growth and composition of the magpie Pica pica

Magpie nestling growth is documented as increments in body mass, tarsus length, and tenth primary length. A sample of 41 nestlings and eight adults was used to provide comparative data on changes in water content, lean dry mass, and fat content for 14 body components.Changes in the composition of various components implicate water index (water content/ lean dry mass) as an indicator of tissue and nestling maturity. Lipid index (fat content/lean dry mass) for the whole body exhibited a sustained linear increase during the first two‐thirds of the nestling period. About 80% of nestling body fat was located in the skin, body shell, and alimentary canal.The state of development of particular components appeared to be related to the current functional requirements of the nestling. Thus the food processing components assumed an early significance, while the development of insulative and locomotory components was somewhat curtailed by comparison.