Around 94% of a western diamondback rattlesnake's diet is made up of small mammals like the prairie dog, the kangaroo rat, the pocket gopher, the vole, the wood rat, the pocket mouse, the white-footed mouse, the harvest mouse, the ground squirrel, the rabbit and moles. They also eat lizards and birds. Some of the birds they eat are the mockingbirds, burrowing owls, black-throated sparrows, and the eastern meadowlark. The lizards they eat are the whiptail liazards, spiny lizards, Texas banded gecko, and the side-blotched lizard. They also eat insects like the ant, beetle, and grasshopper. They usually hunt in the early morning or at night. 