An ornithologist is a type of zoologist who focuses on birds. If you want to know anything about our fine feathered friends, consult an ornithologist.
Having a birdbath in your backyard doesn't make you an ornithologist. An ornithologist is someone who studies ornithology — the branch of science devoted to birds. Ornithologists study every aspect of birds, including bird songs, flight patterns, physical appearance, and migration patterns. Birds are genetically related to dinosaurs, which is something else an ornithologist might study.