Reliability of macroscopic (ocular) assessment of the age of red deer (Cervus elaphus L.) in Slovenia: validation by counting annuli in tooth cementum

To check the reliability of macroscopic (ocular) assessment of the age of red deer (Cervus elaphus L.) obtained by ocular inspection of teeth eruption and wear (done by hunters or hunter commissions), a validation of the precision of these assessments was carried out on a representative sample set, i.e. a total 2008-annual cull of red deer in the entire Slovenia. The reliability of ocular age assessment test was performed by cutting/grinding of the first mandibular molar (M1) and counting the incremental layers of dental cementum on 821 samples of adults (aged from two to twenty-two years). The ocular age assessment of adult red deer (regardless of sex) was biased with a large error (maximum deviation between both assessments: nine years). With both methods, the same animal age was established in 24.5% of cases, and with the age of the animals the reliability of ocular assessment declined. Ages of hinds and younger stags were both under-assessed and over-assessed; however, ages of older stags were generally over-assessed. Out of 426 analysed stags, 142 (33.3%) were categorized in another age category as found by counting annuli in tooth cementum. This raises doubts about the reliability of the current categorization of adult red deer stags into three age categories (2–4 years old, 5–9 years old, and 10+ years old, respectively); indeed, precise (on a yearly basis) ages of adult stags are impossible to be identified by routine age assessment, such as the inspection of teeth wea