Chulin 3:5

If an animal had excessive bodily fluid, or was affected by smoke or the cold, or if it ate oleander or chicken dung, or if it drank noxious water, it remains kosher. If it ate poison or was bitten by a snake, it is not prohibited as a treifa but it is prohibited because it poses a potential threat to one who might eat this animal’s meat.

Chulin 3:6

The features of kosher domesticated and wild animals are given to us in the Torah but the features of kosher birds are not. The Sages said that any bird that seizes its prey with its claws is not kosher, while any bird that has an extra toe in the back and whose crop and craw can be peeled is kosher. Rabbi Eliezer bar Tzaddok says that any bird whose feet are parted (with two toes on each side of a wire) is not kosher.