Pyxicephalus adspersus breeds in shallow pans that fill after rain and can vanish within weeks. After spawning, the male remains with the tadpole shoal and defends it, attacking approaching animals including birds and, in reported cases, people who come too close.
The guarding goes further than defence. Males have been observed digging a channel through mud from a drying puddle to a larger body of water, allowing the tadpoles to swim clear. This is one of the clearer cases of frogs actively modifying their environment for the benefit of offspring, alongside the goliath frog's rock nests.
The protection is not universal. Adult African bullfrogs are voracious generalists that swallow insects, rodents, reptiles, small birds and other frogs, including tadpoles and juveniles of their own species. Cannibalism of the shoal by other adults is a documented risk, and a guarding male will eat stragglers from his own brood. Sexual size dimorphism runs the opposite way to most frogs, with males substantially larger than females.