Mirrors are one those things each individual bird is going to respond in a different way to. Many birds either don't care at all or have no inappropriate behaviors towards mirrors, but there are those certain birds out there who fall inappropriately in love with or become very aggressive towards mirrors. If you are going to use a mirror toy, I highly suggest you carefully observe your birds reaction the first few days and use common sense to gauge if it's a good toy for your bird. Also, if the mirror is directly in your birds cage never use ones that are not integrated into a toy specifically designed for your birds size group. Giving say, a macaw a mirror toy designed for a parakeet could pose a safety threat since a macaws beak is so much more powerful than the intended size group and could break the mirror and cut it's tongue. Never use a mirror not integrated into a bird specific toy inside the cage (like the mirrors you buy at craft stores) as bird mirrors are made of more durable materials than regular glass ones and have a far less risk of the bird accidentally breaking and ingesting or injuring themselves with it. If you place a mirror not specifically designed for birds outside the cage, make sure it is our of reach or carefully watch your bird any time they could have access to it. If your bird wants to chew on the mirror toy, remove it from the cage regardless if it's designed for parrots, it can still pose a risk.
Personally, Kiwi has a little mirror toy in his cage, and he sticks his head in it every so often and tries to figure out who that other bird is, but for the most part, he ignores it for more interesting toys he can forage with or rip up. My parents 2 zons have had mirror toys before, and couldn't care one iota about them. Their cockatoo on the other hand is very aggressive towards mirrors, and he doesn't ever get mirror toys because he attacks them and could accidentally break one and injure himself. It boiled down to the individual birds reaction and common sense on the owners part.
