How Can Birds Eat Poisonous Berries?
Simple. It isn’t poisonous to them. See ‘Why is that plant trying to kill me?’ for a detailed explanation of what we actually mean when we call a plant poisonous. If a creature doesn’t have a substance which will combine with the ‘poison’ in the plant, then that ‘poison’ will have no effect on that creature. Poisons, generally, work in one of two ways. They combine with a substance which is essential to a creature’s life creating a third substance which is excreted. It is the removal of the essential substance which results in the harm. Or, the substance created by the reaction of the ‘poison’ with the substance in the creature is itself harmful to the creature. The best example of the different effect a plant has on different creatures is the Conium maculatum, poison hemlock. The principal active ingredient in poison hemlock is called coniine. For humans it can be a deadly poison working on the peripheral nervous system. That is to say it numbs the extremities first, the fingers and t
