Which is the only snake that builds a nest for its eggs?

The king cobra (Ophiophagus hannah) is an elapid found predominantly in forests from India through Southeast Asia. It preys chiefly on other snakes and occasionally on some other vertebrates, such as lizards and rodents. The king cobra is a dangerous snake that has a fearsome reputation in its range, although it typically avoids confrontation with humans when possible.

The king cobra is unusual among snakes in that the female is a very dedicated parent. She makes a nest for her eggs, scraping up leaves and other debris into a mound in which to deposit them, and remains in the nest until the young hatch. A female usually oviposits 20 to 40 eggs into the mound, which acts as an incubator. She stays with the eggs and guards the mound tenaciously, rearing up into a threat display if any large animal gets too close, for roughly 60 to 90 days.