Most are related to reducing weight for flight:
there wings are really strong like the hawk and egal
Feathers, air sacs, reduction of organs, and a lightweight skeleton. All of these adaptations are for flight.
most birds have four toes but some dont
Some birds do not need to fly, such a penguins, because their food is in the ocean, not the air. After time, they have evolved to not fly. A characteristic of a bird is a beak. Every bird has beak. Other animals, such as tortoises, turtles and dolphins, also have beaks. Every bird has feathers. Feathers keep birds warm, to keep the eggs warm and, well, they wouldn't look good without them. Every bird has 2 feet, a tail, a beak, feathers, and wings.
Cuckoos and bluebirds, plus some others that I dont know of
Feathers - the only outwardly obvious characteristic unique to birds.
dont know this question is weird 2nd Answer: Some birds, like magpies, crows, and tickbirds are carnivores. Other birds like pheasants, canaries, and finches are herbivores. Others birds are omnivores.
relating to, or characteristic of birds.
a Shared ancestral characteristic a shared primitive characteristic
i dont no
Birds and mammals are air breathers. Lampreys are not.
Aquiline ---------- "Aquiline" is specifically eagles. "Avian" is more generally pertaining to birds.
Birds have a 4-chambered heart, a characteristic in common with mammals.