Mating Pattern, Spawning Behavior, and Sexual Size Dimorphism in the Tropical Toad Bufo melanostictus (Schn.)

Pattern of mating, spawning behavior, and sexual size dimorphism were studied in the Indian Common Toad, Bufo melanostictus. Male and female B. melanostictus are sexually dimorphic in size. Adult males are significantly smaller than adult females, and the ratio of body size of females to males was 1:19. For breeding, the majority of males and females segregated on the basis of their size; larger males paired with larger females leaving smaller males to pair with smaller females. A positive correlation between the body sizes of mating partners provided evidence of size-assortative mating. Successful males were larger in length than their unsuccessful competitors. Operational sex ratio was skewed in the favor of males. A stereotypical spawning behavior was observed: At the initiation of spawning by the female, the male juxtaposed his cloaca with that of the female's followed by a few seconds of rigorous toe movements. Spawning was completed within 2–5 h. Subsequently, the female exhibited pseudo-spawning behavior once or twice. In the absence of more eggs, the male quickly released his clasp, and the pair separated.