The herpetofauna of the Owen Sitole College of Agriculture, Zululand.
Hoffmann, Leonard Andrew Charles.
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A herpetofaunal study was undertaken at the 670 ha Owen Sitole College of Agriculture (OSCA) near Empangeni, Zululand, from 1986 to 1988. Collecting was carried out primarily opportunistically, throughout all seasons. A total of 28 amphibian taxa and 44 reptile taxa, comprising two chelonians, one crocodylid, 13 lizards and 28 snakes, were recorded. A further 11 amphibian and 42 reptile taxa may possibly occur. The majority of amphibians and reptiles display a tropical distribution, often with enormous ranges. Nineteen (68%) amphibian taxa have tropical or quasi-tropical (Poynton 1964) zoogeographical affinities and 33 (75%) reptile taxa have tropical wide ranging or tropical east coast littoral (Bruton and Haacke 1980) zoogeographical affinities. Only one amphibian taxon and four reptile taxa, all snakes, have Cape or temperate affinities. These taxa are marginal in the region, reaching their distributional limits in Maputaland. Niche segregation of amphibians occurs primarily according to water bodies. Vegetation per se does not appear to be important, with the majority of species occurring in a savanna environment; however, three species, Leptopelis natalensis, h. mossambicus and Arthroleptis wahlbergii, appear to be sylvicolous in habits and are restricted to riverine vegetation. The vast majority of taxa are summer breeders, whereas only one, Cacosternum nanum nanum, was recorded breeding in winter too. The syrnpatry of h. natalensis and Hyperolius semidiscus was confirmed in this study, and H. semidiscus and H. argus were shown to behave as good species with specifically distinct calls. Snakes are segregated according to size, mode of life, activity patterns and food. Certain species, such as Naja mossambica, have catholic diets whereas others, such as Duberria lutrix lutrix, Aparallactus capensis and Dasypeltis scabra, are specialists. The lizard fauna is differentiated according to diet, foraging strategies and habitat preferences, including substrate and vegetation. Amphibians are unselective feeders, consuming a variety of insects. Some, namely Xenopus laevis laevis and Pyxicephalus adspersus edulis, have catholic tastes and are even cannibalistic. Snakes and amphibians constitute the main prey items of snakes, whereas most lizards, with the exception of Varanus niloticus niloticus which is a generalist, feed exclusively on arthropods, especially insects. Schismaderma carens, Bufo gutturalis, Hemidactylus mabouia mabouia, Lygodactylus caoensis capensis, Mabuya striata striata, Lamprophis fuliginosus, Causus rhombeatus, Duberria lutrix lutrix and Naja mossambica are attracted to places of human habitation either for feeding or for shelter. Many amphibians benefit from artificial water bodies. No less than 19 taxa were recorded from the fish ponds, the majority of which bred there, possibly because the waters are more stable, permanent and relatively free of predators than natural water bodies. The Leguaan Tick Aponomma exornatum was recorded parasitizing adult Varanus niloticus niloticus, and the Snake Tick A. latum was found on N. mossambica and h. rhombeatus; A. latum, with an extensive subSaharan distribution, shows no predilection for any species of snake. Pentastomids and nematodes were found in a number of snakes (Atractaspis, Telescopus, Psammophis and Causus); the life cycle implications of these organisms are that mammals and snakes are intermediate hosts, though more ecological and experimental evidence is necessary. Python sebae natalens is and Kinixys natalensis, both Red Data Book - Reptile and Amphibian species, are particularly threatened, the first due to slaughter for traditional uses, the second due to agricultural activities and frequent fires. It is recommended that both these reptiles be afforded maximum protection in the 110 ha game park, which is regularly patrolled and which is subjected to infrequent fires. Generally, however, the herpetofauna has fared well at the hands of the local people, testimony to which is the high species diversity.