creature not spawning on grass

Im currently working on a badlands mod and trying to add vultures to the biome. The problem is they are creatures, so they can spawn on daylight but as far as ny knowledge goes

creatures can only spawn on grass, which results in my vulture not spawning, as there is almost no grass in all badlands biomes.

my question is, is there a way to make creature-type entitys spawn without needing grass  ?