The breeding migration of the Common toad (Bufo bufo) to a pond in mid- Wales



A pond was completely enclosed by a clear polythene barrier and all toads entering and leaving were recorded over an entire year. The inward breeding migration lasted one month, and the outward migration about one month for females and two months for males. Interruptions in the numbers arriving during the inward migration could be explained by low air temperature. Large males and females arrived before smaller individuals, and males arrived before females, staying about a month, four times longer than females. During the breeding season 865 individuals were captured; the male: female ratio was 4.7: 1. Relatively few toads visited the pond during the summer, but at this time the imbalance in the adult sex ratio was not so great as during the breeding season. Juvenile toads also visited the pond during the summer. It appears that females suffer a mortality rate of about 4.7% per week during their stay in the pond and males a rate of 2.6% per week.