Separating brown and black bears in northeast China using tooth measurements

Abstract

An expeditious method for ascertaining species between black bear (Seienarctos thibetanus G. cuiver) and brown bear (Ursus arctos Linnaeus) was developed using tooth measurements from previously identified specimens. The measurement and analysis on 18 tooth measurement indexes (i.e. T₁. Length of P_m1-P_m4, T₂. L. of M₁-M₃, T₃. M₁L., T₄. M₁ width, T₅. M₂L., T₆. M₂W., T₇. M₃L., T₈. M₃W., T₉. L. of C₁ alveolus, T₁₀. W. of C₁ alveolus, T₁₁. L. of C₁-M₂, T₁₂. L. of P_m ⁴M², T₁₃.M¹L., T₁₄. M¹W., T₁₅. M²L., T₁₆. M²W., T₁₇.L. of C¹ alveolus, T₁₈. W. of C¹ alveolus) of 59 skulls (black bears 25, brown bears 34) indicates that there are significant or the most significant difference between two species in every indexes, however T₁, T₉, T₁₀, T₁₇ and T₁₈ are not suitable for species discriminator because of their high percent of overlap. The efficient species discriminators and standards (mm) are as follows T₂(63.0), T₃(22.0), T₄(10.2), T₅(23.8), T₆(13.6), T₇(18.0), T₈(13.5), T₁₁(110.0), T₁₂(66.0), T₁₃(20.1), T₁₄(15.8), T₁₅(33.0) and T₁₆(17.3). Those who are less than or equal to standard are classified to black bear, the others are brown bear. The method is very convenient and useful with high reliability. Their lowest accuracy percent are 95.0%, most of them over 97%. Different indexes will be chosen refer to the degree of specimen destroyed.