The Past and Present Nesting Ecology of Nile Crocodiles in Ndumo Game Reserve, South Africa: Reason for Concern?

Abstract

Abstract Knowledge of the distribution and abundance of crocodilian nests and threats facing them is essential in calculating recruitment and determining population trends. We studied the nesting ecology of the Nile crocodiles (Crocodylus niloticus) at Ndumo Game Reserve (NGR) in northeastern KwaZulu-Natal, South Africa from 2009 to 2012. Nesting effort in NGR was comparable to other C. niloticus populations at 18–22%. Historical data suggest that high water levels completely inundate nesting sites within the reserve once every 10 yr, whereas predation destroys on average < 20% of nests annually and can be primarily attributed to water monitor lizards (Varanus niloticus). The number of crocodile nests located in NGR remained similar from 1964–2012 despite significant increase in population size. Earlier stocking programs increased the number of C. niloticus in the greater Maputo/Phongola floodplain areas, but these numbers may not be sustainable because the majority of C. niloticus nests appear to be outs...