The giant bullfrog. Graphic by Caroline A. Yetman

The African Bullfrog The African Bullfrog (Pyxiecephalus adspersus) is one of the largest frogs in Africa. Adult males may reach 23cm or more and may weigh over two kilograms. Females are much smaller, whereas in nearly all other species of frogs, the female is larger than the male. The African bullfrog is found mostly in open grasslands and at low elevations in the sub-Saharan African countries of Nigeria, Somalia, lower Sudan, Tanzania, Kenya, Malawi, Zambia, Angola, Mozambique, Zimbabwe and South Africa (except for the south-western Cape). The frogs have rounded bodies with broad heads and have dark olive-green skin on the back with a cream or orange-coloured under-carriage, which it uses to camouflage itself. Adult frogs are very aggressive and inflate themselves when provoked. Male bullfrogs have a bright yellow throat while the throat of the female is cream colour. It is not unusual for African bullfrogs to live for 35 years or more. Their camouflage allows them to blend into the environment while waiting for prey, which can consist of various insects, amphibians, small reptiles and mammals. They are known to bite inquisitive humans using tooth-like projections on their lower jaw. In extreme cases of food scarcity or overpopulation, they even resort to cannibalism. They aestivate during the dry season but come up to the surface to spawn after the first rains. The period of aestivation is around eight months, though some experts claim that they can remain underground for more than five years. Natural predators of the tadpoles and juvenile frogs are mostly waterfowl, other terrestrial birds and snakes, while herons, other large birds and jackals prey on the adult frogs. The females lay 3000 to 4000 eggs in shallow waters and these usually hatch around two days later. However, survival rates of these frogs are thought to be very low. RELATED LINKS: Region 2 One of the two northernmost regions of the city, Region 2 is an area of immense potential that includes the fast-growing Midrand CBD. Read more Region 2 Attractions Bird lovers may visit the Glen Austin Bird Sanctuary and Lory Park Zoo, the latter housing the biggest display of exotic birds in South Africa as well as an owl sanctuary. Read more Environmental Planning and Management Environmental Planning and Management is responsible for a wide range of functions Read more

The Glen Austin pan - a major breeding site for giant bullfrogs in Gauteng. Photo by Caroline A. Yetman

A bid to save the African bullfrog September 22, 2004 By Anish Abraham THE African bullfrog - an inhabitant of the Glen Austin pan in Midrand - has been listed as a "near threatened" species by the International Union for the Conservation of Nature, and Johannesburg City Parks has decided to do something about it. City Parks, along with a residents' group in Midrand, the University of Pretoria and Gauteng's Department of Agriculture, Conservation, Environment and Land Affairs, are investigating the possibility of setting up a conservation area to preserve the bullfrogs' natural habitat. The Glen Austin pan is home to one of Gauteng's largest populations of African bullfrogs. About two thirds of the pan is owned by City Parks, while the rest is in private hands. "We are currently negotiating with land owners in the area so that we can make the whole pan into a conservation area," says John Kruger of City Parks. "One of the main problems is the uncontrolled development in these areas leading to loss of habitat," says Caroline Yetman of the Centre for Environmental Studies at the University of Pretoria, explaining that "near threatened" classification is given to species that are likely to face the future risk of extinction in the wild. As part of her PhD on the Glen Austin frogs, Yetman is currently working on DNA sequencing and fitting some of the frogs with radio transmitters for tracking purposes. Earlier in 2004 Yetman counted some 100 adult bullfrogs in the pan and says this number shows a general decline - a statement supported by many residents in the area. Research conducted by Clayton Cook of the University of the North on the African bullfrogs in the Glen Austin pan between 1991 and 1996 reported that there were between 250 and 300 adults and over half a million juveniles at that time. "These frogs are very difficult to track, so getting an exact figure is difficult," says Yetman, adding that in an effort to track the frogs, "we are requesting that members of the public that spot these frogs should photograph them and send it to us with details of where they were found." The African bullfrogs' breeding grounds are in the poorly drained rocky highveld grasslands of Midrand and Fourways, as well as on the East Rand. The bullfrog pan in Benoni, where around 100 adults used to breed, is believed to be the only other major breeding area in the province, with a large numbers of tadpoles dying because of water contamination. Unlike a stream or river, a pan has no in- or outflow of water. A depression in the ground that is covered by rainwater, it dries up during extended periods without rainfall and in extremely hot summer conditions. Besides affecting the environment, construction developments in Glen Austin are leading to increased water usage and the draining of marsh areas for building. Cook maintains that there has been an 80 percent decline in African bullfrog numbers in the last 10 to 15 years and the possibility of the species becoming extinct in Gauteng area in another 10 years is very real. A primary factor leading to the decline in bullfrog numbers is the destruction of the frogs' habitat. Cook points out that developments in the area in the early 1980s, "including the Fourways Mall, were done on former wetland areas". He adds: "Putting up high security walls has also hampered the breeding of these frogs as they are highly migratory." Another threat to the frogs is the human palate. In some cultures, especially in northern and eastern Namibia, the African bullfrog is regarded as a delicacy. This trend has also surfaced in Limpopo, where the frogs are being unlawfully sold from the back of bakkies for their meat. Cook also claims that these frogs are being illegally caught and sold overseas to collectors. In countries like US and Germany, where demand is high, collectors pay as much as $100 for a large adult male. The African bullfrog, however, is a protected species and trading in them is prohibited, according to Craig Whittington-Jones, a scientist at the Department of Agriculture, Conservation, Environment and Land Affairs in Gauteng. Several hundred frogs are killed on the roads when they leave the pans at the end of the breeding season. "People are also known to catch tadpoles and young frogs from pans and other breeding areas to feed their pet snakes," Yetman adds. "It's really difficult for the police to enforce environmental regulations, you find pet shops in Johannesburg with lizards and other amphibians even though it is illegal to trade in those species," adds Cook. "The only way to help these frogs is by getting as much public awareness and support as possible." To secure the future of the Glen Austin pan and preserve the African bullfrog population in the province, City Parks is working towards forming a Bullfrog Working Group made up of interest groups like local landowners, Ekhuruleni Metro, the Gauteng Department of Agriculture, Conservation, Environment and Land Affairs, the Centre for Environment Studies at the University of Pretoria, the Working for Wetlands and Working for Water groups and the Endangered Wildlife Trust. For more information, contact Johan Kruger or Willie Nell of Johannesburg City Parks on 011 712 6600, the International Union for the Conservation of Nature on 012 342 8304/5/6, or Caroline Yetman at the Centre for Environment Studies at University of Pretoria on 012 420 4283. Permission to use web site material Publishers may use material from this site free of charge, as long as: Credit is given to either the "City of Johannesburg website (www.joburg.org.za)" or to "Johannesburg News Agency (www.joburg.org.za)"; If the article is used online, a link is provided to the original article on this website; The name of the article's author is acknowledged; The webmaster is informed of how and where the material is used (fill in this brief online form). Johannesburg News Agency is operated by BIG Media at 011-484-1400 Print this Page E-mail this article to a friend Help using Joburg.org.za