They start as single cell orginisms then they evolve from there.
hope that helps
Rowdy-rude,rough,wild
Disorderly-disorganized,confused, irregular, cluttered, etc.
Isotopes
The answer has to be 20 characters long so this is irrelevant.
I'd say zoology.
Zoology is the study of animals, generally speaking, and since birds are animals, the study of these fall into the field zoology. The study of birds though, is called ornithology.
Hope it helped,
BioTeacher101