Animorphs #3 The Encounter (K. A. Applegate) - Marco, an Eagle?
At the ending part of the book when the animorphs are flying out of the water carrying ship as birds, the book gets all the bird names mixed up. In #2, and all the other books for that matter, Jake is a Perigrine Falcon, Cassie and Marco are Osprys,and Rachel is a Bald Eagle. I can't remember what she wrote perfectly, but I know she confused their morphs like "Marco and Cassie flew out as bald eagles, and rachel as an ospry."