Vintage children’s book, mistaken identity, animals

Cannot remember what kind of animals were depicted! Premise was an orphaned animal of species A is raised among species B. He/she grows up wondering why they are not a normal “B.” Resolution comes when he/she realizes what their real identity/species is. Thx! (Not Quackers- the book Im thinking of has been around much longer.)

So, this is basically a retelling of The Ugly Duckling?

OP cross-posted here: https://www.librarything.com/topic/294706

yes, that's right-- meaning it's definitely not Ugly Duckling but clearly inspired by it. The book I'm thinking of used the different in two species to create the sense of "otherness" in the protagonist. And not until they find/realize they are not the same species as their adoptive family do they realize they are just fine the way they are, instead of being a wrong type of something.