Crocodilia
Growth and mortality

Eggs and hatchlings have a high death rate, and nests face threats from floods, drying, overheating, and predators. Flooding is a major cause of failure of crocodilians to breed successfully: nests are submerged, developing embryos are deprived of oxygen, and juveniles get washed away. Numerous predators, both mammalian and reptilian, may raid nests and eat crocodilian eggs. Even after hatching and making it to the water, hatchlings commonly fall to predation.

While the female is transporting some to the nursery area, others are picked off by predators that lurk near the nest. In addition to terrestrial predators, the hatchlings are also subject to aquatic attacks by fish. Birds take their toll, and in any clutch there may be malformed individuals that are unlikely to survive. In northern Australia, the survival rate for saltwater crocodile hatchlings is only twenty-five percent, but with each succeeding year of life this improves, reaching sixty percent by year five. Mortality rates are fairly low among subadults and adults, though they are occasionally preyed on by large cats and snakes. elephants and hippopotamuses may kill crocodiles defensively. Authorities differ as to whether much cannibalism takes place among crocodilians. Adults do not normally eat their own offspring, but there is some evidence of subadults feeding on juveniles and of adults attacking subadults. Rival male Nile crocodiles sometimes kill each other during the breeding season.

Growth in hatchlings and young crocodilians depends on the food supply and reach sexual maturity at a certain length, regardless of age. Saltwater crocodiles reach maturity at 2.2–2.5 m (7–8 ft) for females and 3 m (10 ft) for males. Australian freshwater crocodiles take ten years to reach maturity at 1.4 m (4 ft 7 in). The spectacled caiman matures earlier, reaching its mature length of 1.2 m (4 ft) in four to seven years. Crocodilians continue to grow throughout their lives. Males in particular continue to gain in weight as they get older, but this is mostly in the form of extra girth rather than length. Crocodilians can live 35–75 years, and their age can be determined by growth rings in their bones.
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