Freddie could be a scarecrow or a penguin. In the former case he would not be a bird, in the latter he would. Combining these two terms with the concepts of negative and affirmative, we see that there are four possiblities for the categorical statement. All crows are birds. Freddie is a friendly creature.
Dogs are mammals.
Santa Claus is a myth. Some birds are flightless birds. Most birds are beings which are capable of flight. Many cartoon characters are birds. No elephants are birds.