Jokes and riddles on animals

Hey, everyone! Here's a new challenge! Try to guess what the answers to these riddles are. All of them refer to animals and are tricky.

1. How do you spell MOUSETRAP? _ _ _
2. Do you know why birds fly south in winter? ________________________________
3. What do you call a bear without an ear? ___________________
4. What do you call a fish without an eye?  ________________