We should get rid of the tag.
The tag serves no actual purpose, is ambiguous what it should be used for, is not used consistently, and does not meet the criteria for a good tag.
- It's not clear what it means in the first place.
What do we define as "animals"? Does this mean regular, non-SFFnal animals? Does it include centaurs? How does this relate with magical-creatures?
- It's not clear what it should be used for.
What type of questions get this tag? Questions about characters that are animals? Questions about animals within a universe? Questions about dog actors?
- It's not being used consistently (most likely as a result of the above two points).
According to the sidebar on the tag page, out of 93 questions, 37 of them are story-ID. 10 of them are Harry Potter. 8 are Star Wars, 6 are Star Trek, and 6 are history-of. These low numbers show that it's not being used consistently, and infrequently - in the year and two months since this was asked, it's only had another 13 questions with the tag.
- You can't really be an expert in animals in the context of SFF.
What does it mean to be an expert in animals? Since, as I said above, it's not even clear what this covers, and since it is apparently a cross-franchise tag, it's a little hard to be an expert on every animal in SFF works in general. You could be an expert in magical animals, such as mythological animals and their portrayal in SFFna works, but that's covered by magical-creatures (and the more specific tags such as dragon, unicorn, etc). You could be a veterinarian, but that's not going to help you to answer questions about post-apocalyptic sentient animal story-ID questions.
- It doesn't help to filter questions.
It doesn't make much sense as a favorite or ignored tag. Since it's cross-franchise, it's not very useful for someone who doesn't like a topic in a franchise or a franchise as a whole - it's got a whole range of questions covering different franchises and types of questions, none of which are very closely related, and so doesn't help much in filtering tags.
All in all, it seems rather useless to me. I say burn it with fire... dragon style.