In a study, the serrated hinged terrapin ("Pelusios sinuatus") (also sometimes referred to as the "water tortoise") was more commonly reported in the stomach contents of adult crocodiles from Kruger National Park than any single mammal species. Other turtle species commonly recorded among Nile crocodile prey include the Speke's hinge-back tortoise ("Kinixys spekii") and East African black mud turtle ("Pelusios subniger"). Beyond their ready availability and respectable size, turtles are favored by big crocodiles due to their slowness, which allows the cumbersome crocodiles to capture them more easily than swifter vertebrates. While adults have a sufficient bite force to crush turtle shells, younger crocodiles sometimes are overly ambitious, and will choke to death attempting to swallow whole large river turtles. A variety of snakes has been preyed on from relatively small, innocuous species such as the common egg-eating snake ("Dasypeltis scabra") to the largest African snakes species, the African rock python ("Python sebae"), which can exceed in length and weigh over . Venomous species, including the puff adder ("Bitis arietans"), the forest cobra ("Naja melanoleuca"), and the black mamba ("Dendroaspis polylepis") have been recorded as Nile crocodile prey. The only frequently recorded lizard prey is the large Nile monitor ("Varanus niloticus"), although this mesopredator may be eaten fairly regularly, as they often share similar habitat preferences, whenever a crocodile is able to ambush the stealthy monitor, which is more agile on land than the bulkier crocodile.