The layered structure of bones of birds as a possible indication of age

A method of age determination, new in birds, is described. The method has been derived from similar methods commonly used to determine age of fishes, amphibians, reptilians, and mammals. It consists of demonstrating, by preparation of transverse transparent sections, the presence of annual deposits in the periosteal zone (= zone of outer circumferential lamellae) of bone. Evidence is presented that the layered structures in the periosteal zone are indeed annual and thus related with age.