Breeding behaviour of the African frog, Chiromantis xerampelina: multiple spawning and polyandry

Breeding was observed in the foam-nest frog, Chiromantis xerampelina, in Hoedspruit, South Africa. The population had a 3-week breeding season with a male-biased operational sex ratio and asynchronous and unpredictable female arrival. Nests were built above water and at 14 out of 15 nests, from one to seven unpaired males (‘peripheral males’) gathered around the amplexing pair during nest construction. Those peripheral males closest to the pair competed with each other, and with the amplexing male, to position their cloacae aginst the female's cloaca during oviposition. It is suggested that multiple spawning was occurring. Of 30 males, 25 (83%) were observed as peripheral males, and 17 (56·7%) were observed both in amplexus and as peripheral males. Male mating success and participation at nests was unrelated to size or weight. Chorus participation was the best predictor of mating success and presence at nests. Nests were built in two to four sessions with females descending to the water between sessions. On 55% of 20 occasions amplexing males dismounted between sessions, but they had only an 11% probability of re-amplexing when the female returned to the nest. Of 15 females, 10 (66%) mated polyandrously with two or more males on one night.