Individual age is an important element in models of population demographics, but the limitations of the methods used for age determination are not always clear. We used known-age data from moose ( Alces alces ), red deer ( Cervus elaphus ), semi-domestic reindeer ( Rangifer tarandus tarandus ) and Svalbard reindeer ( Rangifer tarandus platyrhynchus ) to evaluate the accuracy and repeatability of age estimated by cementum annul...