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The skulls of shrews of genus Sorex from eight samplings from the European part of Russia and two from the vicinity of Novosibirsk were compared. The characteristics were identified using 22 marks on the axial skull. It was found that the centroid size differs significantly in the common and Laxmann's shrews S. caecutens and the pygmy shrew S. minutus, while for selected marks, the common and Laxmann's, as well as pygmy, shrews were significantly different in form, but the differences were very small between Laxmann's and pygmy shrews. The characteristic features of the biology of the shrews Sorex are discussed, which may contribute to understanding the general laws of the morphological evolution of the genus.

The activity of average statistical species was approximated by normal distribution. This is provided by calculation of the part of resident animals without repeated hatching, i.e., the edge effect. Residence beyond the space covering 99% of species activity was considered as nonresidence. The appearance of nonresidence in general can be considered as "excursions" and "resettlement." The experiments on requisitioning of small settled animals from a preliminary marked site were carried out. It was shown that the number of settled small animals calculated using results of requisitioning corresponds to the number found during labeling with amendment to the edge effect, and immigration was constant and is not initiated by requisitioning. Only resettlements had an influence on the settlement of free space. The expected velocity of settling of the free space was calculated according to evaluation of the value of settlement and the share of "migrants" among immigrants. Second labeling of the place of hatching has shown that the expected and real paces of settlement are close.

The home range of resident animals is considered as "known territory" including a "foraging region." It has been revealed that the activity of an average animal unit in the "foraging region" could be approximated by normal distribution. Estimation of activity distribution in the "known territory" (beyond the "foraging region") was impeded by means of marking since it might be difficult to detect the frequency of distant translocations, and the method does not provide an essential body of data. In the case of the common shrew Sorex araneus, the "known territory" was estimated using trap cones as animals evade them in the known areal. The "foraging region" radius of the average shrew was taken to be 30 m (95% of the animal unit activity), the radius of known territory was within the range of 180-240 m. The "foraging region" was expected to provide the animal with vital resources, and the "known territory" reflects its need for exploratory activity.

The behavior of three common shrew species was compared in a test of pairwise placement in a neutral territory (10 min) for various population densities in natural habitats and for animals kept isolated or in groups in open-air cage conditions. The behavior of the animals captured in nature was considered as the norm. We considered total number of social contacts (as an index of social activity), as well as the proportions of direct and ritualized aggressive interactions, contact avoidances, and friendly interactions (as a description of the interaction structure). Isolation of the shrews proved to decrease their social activity. Top frequency of interactions was observed in the animals kept in groups in open-air cages. The level of "sociality" and the changes in behavior related to different population density can be more significant in the three shrew species than the species-specific differences in their behavior.