Hatchling Nile crocodiles are between long at first and weigh around . The hatchlings grow approximately that length each year for the first several years. The new mother will protect her offspring for up to two years, and if there are multiple nests in the same area, the mothers may form a crèche. During this time, the mothers may pick up their offspring either in their mouths or gular fold (throat pouch), to keep the babies safe. The mother will sometimes carry her young on her back to avoid the natural predators of the small crocodiles, which can be surprisingly bold even with the mother around. Nile crocodiles of under two years are much more rarely observed than larger specimens, and more seldom seen than the same age young in several other types of crocodilian. Young crocodiles are rather shy and evasive due to the formidable gaunlet of predators that they must face in sub-Saharan Africa, spending little time sunning and moving about nocturnally whenever possible. The two-year-and-younger crocodiles may spend a surprising amount of time on land, as evidenced by the range of terrestrial insects found in their stomachs, and their lifestyle may resemble a semi-aquatic mid-sized lizard more so than the very aquatic lives of older crocodiles. At the end of the two years, the hatchlings will be about long, and will naturally depart the nest area, avoiding the territories of older and larger crocodiles. After this stage, crocodiles may loosely associate with similarly sized crocodiles and many assuredly enter feeding congregations of crocodiles once they attain , at which size predators and cannibal crocodiles become much less of a concern. Crocodile longevity is not well established, but larger species like the Nile crocodile live longer, and may have a potential average life span of 70 to 100 years, though no crocodilian species commonly exceeds a lifespan of 50 to 60 years in captivity.