Fleas from bird nests in southwestern Tuva

14 species of fleas were recorded from 173 nests of 47 species of birds. Most abundant of them are Ceratophyllus vagabundus, C. gallinae, C. borealis. The abundance of fleas was found to depend on season and hosts' habitat. The above species were most frequently encountered in nests in May. The high abundance index of fleas was registered in birds nesting in hollows, burrows of small mammals and in clefts of rocks.