Abstract
Small mammals in the Horšianska dolina-Valley were researched first in 1984–86 and later in 2016–19. This paper seeks to identify and assess the species composition and dynamics of fleas (Siphonaptera) found in the valley on small mammals of Rodentia and Eulipotyphla and to compare findings from these two periods separated by thirty years. The results indicated deviations in small mammal and flea community similarity as well as in the small mammal indicator species for each habitat and flea indicator species for the small mammal species. A total 12 different species of small mammals were captured, and 12 flea species were collected. Eight flea species were detected in 1984–86 and ten species were found in 2016–19. In both periods A. penicilliger, C. assimilis, C. solutus, D. dasycnema, N. fasciatus were captured. The differences were that in the earlier period, the species uncovered were C. congener, P. bidentata, and P. soricis, while in the later period they were C. agyrtes, C. bisoctodentatus, M. turbidus, and R. integella. In the relationship between fleas and small mammals, C. solutus was the specific species for Apodemus flavicollis, while A. penicilliger and C. agyrtes were for Clethrionomys glareolus, and C. assimilis was for Microtus arvalis.