If biography means:
- an account of someone's life written by someone else.
- biographies as a branch of literature.
- a human life in its course.
What would a biography based on a particular animal be called?
Biographies of animals are not a very common genre, although it is not difficult to find examples with a bit of digging:
A biography of an animal can be called in "animal biography". However, books about animals are sometimes classified as "juvenile literature", sometimes as "biography", depending on the audience rather than the individual whose live is being described. I have never come across the term "animal biography" in a dictionary of literary terms and don't expect it to become a literary term in the near future.
It would be called an animal biography or juvenile literature.