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Abstract.
A simple method of age determination in red fox (Vulpes vulpes) is described. It is based on counting dentine layers on longitudinally sanded canine roots without the tedious procedure of preparing histological sections. The method makes it possible to estimate rather reliably the age of red fox specimens from one year onwards.
Key words: sanding of dental roots, counting dentine layers
Exact individual age determination is an important part of population studies in various animal groups. In the case of red fox (Vulpes vulpes), several methods have been used, based on body weight, body length, cranial dimensions, dry weight of eye lenses, degree of fusion of cranial sutures or development of the sagittal crest, tooth wear, occlusion of the dental pulp, or increments in dentine layers (Klevezal & Klejnenberg 1967, Bree et al. 1974, Harris 1978, Nelson & Chapman 1982, Driscoli et al. 1975, Goszczynski 1989, Wanderer & Lüps 1993, Ansorge 1994, Cavallini & Santini 1995, Zapata et al. 1995 etc.). Counting the increment layers of secondary dental cement is considered relatively the most exact method. In sections through the tooth roots, they appear as characteristic annual rings consisting of paler (summer) opaque and darker (winter) transparent areas (e.g. Klejnenberg & Klevezal 1966, Grue & Jensen 1973, Harris 1978, Nelson & Chapman 1982, Cavallini & Santini 1995, Zapata et al. 1995). Longitudinal sagittal sections are more satisfactory, as in the technically simpler transverse sections the interpretation of the number of increment zones may be problematical since the cement layers are not uniformly spaced on the outside of the root and, hence, it is significant to select a suitable level of the section. While the reliability of this latter method is up to 90% (Grue & Jensen 1973), its notable drawback is in being considerably time-consuming. The tooth must be decalcified with 5% nitric acid (36-48 hours) and subsequently rinsed with water (24 hours), then the transverse section 20 µm thick must be made with a freezing microtome (at -20 °C) and stained using standard histological techniques...