It can also be hard to find books with children who are BIPOC. It is far more common to find books depicting African Americans in urban settings than in nature. Here is a list, that is by no means comprehensive, but a great starting point for Otter and Chipmunk storytimes.
Reading books with children with a wide variety of skin tones helps them view themselves and others more positively. It helps children to see themselves in others and relate to other people better when they read books with a wide variety of people. Hopefully, this list gives you some ideas for some storytimes with your otters.
For adults: Care Work by Leah Lakshmi is amazing to think about inclusion of people with disabilities.