African or Edible Bullfrogs (Pyxicephalus edulis) spend up to 10 months of the year below the soil surface in a dormant state called aestivation. They emerge to breed after enough heavy rain has fallen to fill shallow depressions and ditches with water. The males make their deep “whoop” call that often occurs as burst of sound with several males following the lead of the first frog that calls (known as antiphonal calling). Males gather in loose congregations, and fights often break out, with dominant males charging, tossing and biting rivals. These conflicts are sometimes fatal. An explosive Bullfrog breeding event occurred near Shingwedzi Rest Camp in Kruger National Park in February 2010. Hundreds of male Bullfrogs began calling in a shallow claypan, and many fights broke out. Fighting males inflated their bodies in order to make biting attacks by other males more difficult.