Johannesburg, May 7 : The South African City of Tshwane warned visitors to the Rietvlei Nature Reserve in Pretoria and residents nearby to be vigilant as a cheetah who escaped from the reserve is still at large. It has been reported that the two-year-old cheetah went missing on Tuesday and rangers have been searching for her, reports Xinhua news agency. Local newspaper quoted Natalie Vos, Tshwane's functional head of nature conservation, as saying on Thursday that the animal escaped through a hole under the fence. The cheetah has a neck collar that sends signals for tracing purposes, she said. "We believe the battery of the collar around her neck might be low and that makes our search very challenging." Vos said the area where the animal was last seen "is very overgrown". There are about 1,326 cheetahs in South Africa of which approximately 500 free ranging cheetah live on unprotected farm lands in the northern part of the country. /IANS