[An animal] that is seized with blood, or that inhaled smoke, or that was overcome by the cold, or that ate oleander, or that ate the dung of chickens, or that drank bad water, it is fit. [If] it ate poison or [if] it was bitten by a snake, it is permissible insofar as treifah is concerned, but it is prohibited because of danger to life.

The characteristics of animals and beasts were stated in the Torah, but the characteristics of fowl were not stated. The Sages, however, said: Any bird that seizes its food is nonkosher. Any one that has an additional toe, a crop, and its gizzard can be peeled, it is kosher. R’ Eliezer bar Tzadok says: Any bird that parts its toes is nonkosher.