Twenty-seven bird and nine small mammal species were found within a clearing of the Moravskoslezske Beskydy Mountains (Czech Republic) induced by air pollution. Of the breeding birds, meadow pipit Anthus pratensis showed the highest average density (117 pairs.km(-2)) and dominance (29.2%), whereas the values in other species ranged from 7 to 57 pairs.km(-2) and 1.7 to 15.0% respectively. In small mammals, the highest average values were reached by field vole Microtus agrestis (2,346 individuals.km(-2) and 57%), whereas the density and dominance of other species ranged from 100 to 1,138 individuals.km(-2) and 0.2 to 26%, respectively. The total average density of breeding bird community reached 400 pairs.km(-2), that of small mammal community 4,231 individuals.km(-2). Clearings following clear-cutting dead or dying forest stands created entirely new ecological conditions for birds. All tree layer or canopy-dwelling species were absent there, and, on the other hand, five open area dwellers colonized this habitat. The total average density of breeding bird community per km(2) was markedly lower compared to the bird community of an old forest stand located 1 km southwards. As for small mammals, clearcutting only slightly reflected in the species composition, whereas the population density and dominance of both individual species and the whole community changed markedly.
