Aging Sambar (Rusa unicolor) using Cementum Annuli and eruption and wear: implications for predicting populations

Aging Sambar (Rusa unicolor) using Cementum Annuli and eruption and wear: implications for predicting populations

Sambar (Rusa unicolor), one of six introduced deer species to Australia, are poorly studied and declared vulnerable in their native range of India and southern Asia. In south-eastern Australia sambar are increasing in abundance and distribution despite commercial venison harvest and unlimited public hunting. The ability to accurately age individuals is important for management of cervid populations because many life history events are age dependent. The techniques most widely used to estimate the age of cervids involve tooth eruption and molar wear (EW), and interpretation of cementum annuli (CA) in incisors. Aging techniques based on teeth are influenced by diet, ingestion of soil, body condition and metabolic stressors such as disease and reproduction. We compared age estimation derived by both EW and CA techniques and applied age estimates from both techniques to lifetables and the Euler-Lotka equation to predict population growth. Sambar have CA that are discernible and correspond to mid-winter despite calving throughout the year in a temperate environment. Age estimation by eruption times of molar teeth appears reliable in sambar but estimation based on wear patterns of molar teeth is less accurate than CA. Assuming the accuracy of CA, aging by EW was less than 30% for sambar three years and older. For management purposes however estimation of rates of population growth using either the Euler-Lotka equation or a lifetable provided similar outputs using ages estimated by either CA or EW.

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