Population status of Nile crocodiles in Ndumo Game Reserve, Kwazulu-Natal, South Africa (1971–2012)

  • Published source details Calverley P.M. & Downs C.T. (2014) Population status of Nile crocodiles in Ndumo Game Reserve, Kwazulu-Natal, South Africa (1971–2012). Herpetologica, 70, 417-425.


This study is summarised as evidence for the following.

Action Category

Release captive-bred reptiles into the wild: Crocodilians

Action Link
Reptile Conservation
  1. Release captive-bred reptiles into the wild: Crocodilians

    A study in 1967–2009 along two rivers and associated floodplains in KwaZulu-Natal, South Africa (Calverley & Downs 2014), found that after releasing captive-bred Nile crocodiles Crocodylus niloticus, the number of crocodiles counted in the wild increased over 30 years, but then began to decline. Results were not statistically tested. In the 1990s, thirty years after a programme to breed and release Nile crocodiles began, the crocodile population numbered 937–1066 individuals, compared to 344–351 individuals in the 1970s. In 2009, fifteen years later, the population numbered 128–846 individuals and the authors reported that it may have been declining after peaking in the 1990s. In January 1967–November 1974, a captive-breeding programme produced, reared and released 1,257 Nile crocodiles into a game reserve (10,000 ha). Crocodile abundance was monitored on two river systems using aerial surveys (carried out by helicopter or airplane) in 1971–1973, 1985–1986, 1989–1990, 1992–1994 and 2009. Results reported here were corrected for differences between survey methods (see original paper for details).

    (Summarised by: Katie Sainsbury)

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