[simplyesl]

I LOVE teaching animals to young learners, it's really fun. Use plenty of TPR. For example teaching 'bee' - introduce with a soft toy or a puppet (or a flashcard). Drill the word and sentence structure (It's a bee.) Pretend that the bee (puppet/toy) is alive (I use my hand and make a buzzing noise if I'm using a flashcard). Go around to the students and pretend that the bee is biting them. You'll get a good reaction from them, sometimes unpredictable, ask them "What is it." they should answer "It's a bee." I would settle with 'bee' for the younger kids.
Charades is a great activity for animals.
Old McDonald's Farm is a good song to use.
You could try playing "teacher says (Simon says)" for classroom commands.