MOVEMENT AND ABUNDANCE OF THE YELLOW-BELLIED TOAD BOMBINA VARIEGATA

Abstract

A mark-release-recapture study of individual yellow-bellied toads (Bombina var- iegata) was carried out along a semi-isolated 1 km segment of a small stream in the Balkan Mountains. Movements during spawning activity, seasonal migrations, movements from year to year, abundances, and sex ratios were estimated. Males moved an average of 63.8 m between captures during the spawning season while females and juveniles moved 20.0 and 17.4 m, re- spectively. Movement upstream was not different from that downstream during the spawning season. The animals moved several hundred meters at the end of the spawning season. Thirty animals marked in 1977 were recovered in 1978; 15 moved upstream and 14 downstream but the movements downstream were almost three times as far as those upstream. The sex ratio was 3 males to 1 female during the spawning season but dropped to 2:1 later in the summer. The approximately 480 adult animals along the stream were clustered slightly at the upper end and in pools along the stream.