Only 70 percent of the world's snakes lay eggs. The rest give birth to live young. Oviparous—or egg-laying—snakes tend to live in warmer climates, which helps incubate their eggs. Viviparous—or live-birthing—snakes tend to live in cooler regions, where the ground is too cold for the eggs to develop on their Snakes lay their eggs the same way a bird does. After mating, when the eggs are fertilized, they are coated in shell and then laid own and