The most common domesticated bird in the world is the domesticated chicken, and the most common wild bird is the house sparrow. As of 2011, there were 50 billion chickens and 1.5 billion house sparrows in the world.

Birds are the only direct descendants of dinosaurs living today. House sparrows are thought to have existed more than 100,000 years ago, and scientists believe that this type of bird interacted frequently with humans 10,000 to 20,000 years ago. They can now be found in every part of the world, including the Americas, Africa and Europe.

Adult house sparrows eat a combination of grains and insects, while the babies eat mostly insects to help them grow. Although many farmers consider them pests because they make a meal out of crops, without the house sparrow, the insects on the crops would destroy more plants than the sparrows ever could.