Question: are monarchs poisonous to birds?
Answer: Monarch caterpillar on common milkweedFLICKR, USFWS MIDWESTMonarch butterfly caterpillars have evolved the ability to store toxins known as cardenolides, obtained from their milkweed diet, specifically to make themselves poisonous to birds, as has at least one other species of milkweed-munching caterpillar, according ...