Are birds part or the animal kingdom?

Animals belong to the kingdom Animalia. Any organisms in this kingdom are: * eukaryotes (meaning that their cells have nuclei. Each nucleus is in charge of controlling its cell's activities) * multicellular (meaning they are made of more than one cell) * show cell specialization (meaning that different cells perform different functions) * heterotrophic (meaning that they cannot make their own food like plants do. They have to eat it somehow)