Some species have very generalised diets but many taxa have narrow prey preferences -LRB- stenophagy -RRB- and correlated morphological specialisations , e.g. for feeding on other snakes , elongate burrowing lizards , squamate eggs , mammals , birds , frogs , fish , etc. .

They have also adapted themselves , to better be able to feed on other snakes , certain lizards , squamate eggs , mammals , birds , frogs , fish , etc. .
