Ornithology is the study of birds. A person who studies birds is called an ornithologist.
Konrad Gesner wrote his Vogelbuch and Icones avium omnium around 1557. Later, England developed a tradition of ornithology. Francis Willughby, John Ray, Gilbert White, John Gould (who studied the birds of Australia) and Peter Scott are good examples.
What ornithologists do change
Ornithologists typically trap birds for a closer look at them. This does not hurt the bird. Trapping birds can be done with in different ways, depending on the type of bird. For example, mist nets cause birds that fly into them to fall into a small pocket where the ornithologist can come back later and take a closer look.
After the bird has been caught, the ornithologist will usually inspect (take a close look at) the bird. They may also attach a small ring to the bird's leg before releasing the bird. The ring allows ornithologists to study the bird's migration patterns, how long they live, and other information about the bird's species.