Spirit Animal- is an animal/bird/fish/reptile, that you specifically identify with. Here’s a fairly accurate test you can take. http://www.spiritanimal.info/spirit-animal-quiz/
Totem Animals are important animals in your life that you will see repeatedly. For me the crow and rabbit are two strong totems. These creatures are sacred and serve as guides in my life. There are times when your guides switch out. According to Native American lore, a person can have up to nine different totem animals. Sometimes your spirit animal and totem are one and the same.
Animal messenger is an animal who appears in your real life or dreaming world to bring a specific message. The message can be from your subconscious or even from departed friends and relatives. It can also be a reaction from the natural world too. The difference from an animal messenger than a totem or spirit animal, is the messenger arrives, delivers the message and leaves. Once in my life, a sloth may be a messenger, but it does not mean I’ll ever see the sloth again.
It is good to determine your central spirit animal and the totems. Once you do, read as much as you can about them. Too often, we think we know an animal by assuming common myths we’ve heard. For example: did you know a chickadee can lower its own body temperature to accommodate dipping temps. A snake is temporarily blind when it sheds its skin. Why is it important to know these things?
If a chickadee is your totem animal or even a messenger, it is reminding you to be adaptable. If a snake has crossed your path, it demonstrates that often you have to be vulnerable to grow.
Still, not sure what animals keep making repeat appearances in your life. Start keeping a journal. Totem animals often are not afraid of you. Over three years ago, I had baby bunnies birthed in my yard. This was not something I wanted, but I refused to poison, trap, or kill the bunnies. My dog gave them a little scare, but I think they eventually figured out that he wouldn’t hurt them. The rabbits continue to graze in my yard, allowing me to walk within a foot of them.
One also returned to die in my yard. I’m not sure if it was a natural death or helped along. I honored the rabbit by taking it to the woods as its final resting place. This makes me fairly sure a rabbit is one of my totem animals. As for my spirit animal, I am still a bear.
Can spirit animals change? Yes, especially if the person has a profound psychological change. More likely, the totem animal guides change. Different guides appear for various parts of your life.
In case you’re wondering, no animal is better than the other. A person with a warthog as a spirit animal is just as valuable as one who has a dragon.
Here's a little more about a bear messenger or totem.