All Vipers (except one) give live birth. Althought he term can be misleading. They are actually developed and born in eggs within the mother's body. The eggs simply do not form all the way and remain as embryonic sacs. Shortly after the sacs are "laid", the young break free. So they are actually eggs, but they are developed inside the mother and even at the point of being born inside the sac, they are wiggling. So it is still a live birth, even if it is not neccessarily a mammilian style birth.
I planted some bird seed. A bird came up. Now I don't know what to feed it.