Modern birds are characterized by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings; the ones who didn’t are already extinct.
Birds communicate through melodies, and a recent study suggests that urban birds living in cities perform a type of “avian rap” while their rural counterparts are sticking to a more traditional sound of slow melodies.
Apparently, this is due to the very noisy conditions in which urban birds find themselves into, which makes them, have to sing at different pitches in order to communicate with other birds and attract mates.
