The behavior of the animals in your dream can obviously vary - they can be aggressive toward you, friendly, they can speak to you or just appear briefly.
Different animals have different meanings and can represent separate aspects of your life.
If you dream of crows, ravens or vultures, which were seen as harbingers of something bad even back in ancient times, then be sure to avoid an event or person in real life that you're afraid of at all costs. The fact that you're ignoring them doesn't mean they've given up, quite the opposite - they're lingering around you with the hopes that you'll fail.
This dream is also a symbol that you're trying not to pay them any mind in your daily life but your subconscious is giving you a sign that it's time to face your fear.
All other birds are most often a symbol of gossip, while your attitude toward their songs in your dream is showing you what your attitude should be in real life as well.
The snake has a double meaning in dreams because on the one hand it causes fear, while on the other it embodies wisdom we must learn. With this dream, our subconscious is telling us not to label a given situation or person from our daily life as a threat but to get to know them better, despite them instilling negative emotions in us.
Fish in a dream represent travel but also the primal instincts we can't fight. This sort of dream most likely reveals our desire for new adventures or is showing us that we're trying to suppress our physical attraction toward someone.
Dogs can embody both friends and foes from real life. If the dog is aggressive toward you, it means you're facing serious competition or quarrels in reality. But if the dog is playful and friendly, you can count on the loyalty of your friends.
Cats exemplify intuition and their appearance in a dream has an important meaning when you're faced with a choice or expected to make an important decision. The cat's behavior may be a signal about what you have to do or advising you to consult the occult before you undertake changes.
Those who have a rat as a pet in real life likely see it as a loving creature and that holds true for dreams as well. But for most people, the rat is a symbol of the horrors of poverty and misery. If you're afraid of rats in real life, your greatest fear is likely being left money-less and having to live in destitution. In dreams, the meaning of rats is the same, with your subconscious trying to warn you about where and who might trick you into losing money.
Bears in a dream, like snakes, symbolize something we're extremely afraid of but which may greatly help our progress. A bear appearing indicates that fear is useless and even though it may be hard, it's better to take a step toward change.