I am extremely impressed by the Giant African Bullfrog. It is not because of the species’ attractiveness or lack of same. I’m not one to judge how attractivean amphibian is or should be. No, I am impressed by what the Giant African Bullfrog does as a parent. The pools where the eggs and tadpoles were laid are watched over and guarded by the fathers against not only predators but environmental changes within the pool.The actions taken by these frogs to assure the survival of the offspring are so nearly unbelievable, that I had to write about it.
Pyxicephalusadspersus, known as the Giant African Bullfrog or, to pet owners, the Giant Pyxie, is the largest amphibian found in South Africa. It is also native to Angola and several other countries, extending as far north as the Nairobi, Kenya area. Males reach a snout to rear length of 245 mm and can weigh as much as of 1.4 kg. Females are slightly smaller. The bottom jaw has three hard structures called odontodes which are like teeth and assist in holding prey. In 2013 the species’ status was assessed by the International Union for Conservation of Nature and Natural Resources as “Least Concern”, meaning this frog has a presumed large population and is able to survive in many habitats. The wild populations are generally decreasing, especially since the species’ breeding areas cannot withstand the effects of urbanization.
Several species of frogs, caecilians and salamanders take care of their eggs or their young but none do it quite the way this ungainly green fellow does it. A number of female Giant African Bullfrogs will choose a single pool for egg laying. Several males will then look after the eggs. According to researchers C. L. Cook, J. W. H. Ferguson and S. R. Telford, their larger size is the probable reason why the males have this responsibility. In just a few days the pool is nearly filled with a teeming mass of as many as four thousand black tadpoles. There will be fewer tadpoles in a few more days because though their preferred food is algae, some tadpoles will eat other tadpoles. If there are times when the pool begins drying out, as sometimes happens with algal filled water bodies with little to no flow, the adults guarding the young ones will use their hind feet to excavate a channel to connect the pool with a larger body of fresher and cooler water. Although the males sometimes step on and occasionally eat some tadpoles in the process, they save most of them. The male bullfrogs will even attack predators bigger than themselves that come to consume the eggs or tadpoles, often at the expense of their own lives. Thirty-three days later the tadpoles have metamorphosed into frogs and the fathers’ duties are done.
How these hydraulic engineers and construction workers of the frog world know when it is the appropriate time to dig a channel, and how they know where to dig the channel, is something that the scientific paper I have read does not address fully. Perhaps none of the researchers know. It is not a random behavior.If the male bullfrogs were human beings we would say they are using their reasoning powers to know that a channel must be dug in a certain place to save the offspring. But a frog, no matter how clever it appears, is not a human being and so we must exercise caution when discussing how it knows what to do.I have to wonder whether the frog uses his sense of smell, his sense of hearing or his sight, or all three, plus some other sense. One day we may know. One thing is certain, this species provides for their next generation very admirably!
For Further Reading
Barnes, Keith. 2016. Animals of Kruger National Park. Princeton University Press. 176 pages.
Cook, C. L., Jan W. H. Ferguson and S. R. Telford. June 2001. Adaptive Male Parental Care in the Giant Bullfrog, Pyxicephalusadspersus. Journal of Herpetology 35(2):310
Stuart, S. N., A. Channing, J. Harrison, J. Poynton, K. Howell and L. Minter. 2013.
International Union for Conservation of Nature and Natural Resources – Red List of Threatened Species: Pyxicephalusadspersus Downloaded April 17, 2018.