Skull variability of Mustela nivalis Linnaeus, 1766 in Poland

Abstract

The skull variability of Mustela nivalis Linnaeus, 1766 was studied with regard to age, sexual dimorphism and geographical distribution. The material consisted of 271 skulls from Poland. Linear dimensions of weasel skulls slightly increased with age. The changes in skull proportions were related to braincase diminution and increase in viscerocraniu m. In females, there was an obvious age variation in correlation structures which indicated synchronic growth and periods of stabilization. Sexual dimorphism was expressed by larger dimensions and different proportions in male skulls. The values of coefficients of variation were higher in males than females. Adult skull size was reached earlier by females than by male weasels. The correlation structures of male and female skulls were different. The skull dimensions increase from north-east to south-west Poland. It was revealed, that weasels from Poland but Silesia belong to the subspecies Mustela nivalis vulgaris Erxleben, 1777. Weasels from Silesia may probably form a separate subspecies Mustela nivalis trettaui Kleinschmidt, 1937.