who study bird
An ornithologist is the type of scientist who studies birds. A biologist will also study birds along with a variety of other animals.
Ornithology (from Greek ornitha = chicken and logos = word/science) is a branch of Zoology or Biology concerned with the scientific study of birds, creatures belonging to class Aves. Aristotle was perhaps the first person who wrote on ornithology and mentions more than 170 birds.