Age determination in the Red Fox (Vulpes vulpes): a comparative study [Určování věku u lišky obecné (Vulpes vulpes): srovnávací studie]
Miloš Anděra , Jana Roulichová
The paper summarises the results of comparing several non-metric methods of age determination in the red fox, based on skull material. The methods under comparison include examination of tooth wear(M1) and occlusion of selected cranial sutures (os basioccipitale-os basisphenoidale, os praesphenoidale-os basisphenoidale, and sutura maxilloincisiva), the size of the longitudinal fi ssure on the crowns of canines, and the number of increment layers of secondary dental cement. The wear of M1 shows rather great individual differences ranging up to two years from the actual age of the individual under study. As regards the cranial sutures under study, juvenile individuals can be differentiated from subadult (largely yearling) ones by the time sequence of the occlusion between os basioccipitale and os basisphenoidale. The interval between the occlusion of os praesphenoidale and os basisphenoidale permits a rather reliably to differentiate between foxes 1 to 1.5 years old and those 2 to 2.5 years old (naturally, using the theoretical birth and death dates). The process of occluding dental pulp can be followed up by the presence and size of the longitudinal fi ssure on canines, which arises as an artefact due to the drying up of prepared skulls; using that clue, one can determine the age of a fox between two and three years. A tentative tool has been compiled by which to estimate the approximate age of red foxes up to two years of age by using external characters on their skulls and dentition. The age of older individuals can be estimated by counting the increment layers of dental cement on longitudinal ground preparations of dental roots(preferably canines). In the material of the red fox skulls obtained from various places in the Czech Republic roughly a half were individuals less than one year old (♂♂ 53%, ♀♀ 50%), two-year-old foxes accounted for roughly one third (♂♂ and ♀♀ 29% each), and the remaining 20% or so comprised individuals older than two years. The mean age of the red fox sample under study is 17.9 months (♂♂ 18.1, ♀♀ 17.7 months); the oldest individual (a ♀) was estimated to have been 95 months of age.