Geographic variation and sexual dimorphism in body size of the Egyptian mongoose, Herpestes ichneumon in the western limit of its European distribution

•Egyptian mongoose evidenced sexual dimorphism in body size of adult animals.•Egyptian mongoose males were significant larger than females.•Animals from south of the Tagus River were larger in body size than those from north.•Average weights and main body measurements of juveniles and sub-adult were reported.

The Egyptian mongoose (Herpestes ichneumon) is a carnivore game species in Portugal, whose fundamental ecology remains to be fully explored. For instance, the physical features of this species have not yet been studied through a continuous wide area, as an entire country. In this work, the averages of eight biometric parameters and body mass of both genders were determined for 559 free-ranging animals from four age classes that were established by dental growth.Sexual dimorphism in body size of adult Egyptian mongoose is reported for the first time in the Portuguese territory, with males being larger than females. Differences across regions are also evidenced, with animals from south of Tagus River being larger than those from the north.Comparison with similar data available from other mongoose populations of the Mediterranean basin suggests that adult specimens from Portugal are less heavy than animals from Doñana in Spain and Israel, while males appear to be larger in body length.Statistically significant differences encountered among gender, age and region, suggest that sexual selection, prey availability, human constrains and different habitat use patterns regulate the body size of this species.