There are about 10 000 species of birds on the planet, all classified in the Class Aves. There are almost 30 Orders of birds in this class. Hear is a list of representative birds by Order. Go to an...
"They are all birds" is the preferred structure, both grammatically speaking and to the native ear. In this case, "all" is functioning as an adverb with "are" to indicate that there are no...
Well, perching birds such as the songbird can be one. There are however more than 5000 types of species so predicting which type of birds are wheter if you studied ornithology.