"We didn't realize how many backyard birds there were, even in Los Angeles County," she said.

This free app has the same core functionality of the primary Peterson Birds app, but includes details on 160 backyard birds.

What our backyard birds may lack in quality, they certainly make up in quantity.

It is a common "backyard bird," often seen in urban areas that contain gardens and orchards.

Owners of "backyard birds," including chickens, exotic pets and game fowl, were reimbursed $5.1 million.

One example of a sexually selected trait with direct benefits is the bright plumage of the northern cardinal, a common backyard bird in the eastern United States.

"The sheer volume of these backyard birds has been eye-opening to us," Dr. Breitmeyer said.

Game birds are not typical backyard birds, but in the appropriate habitat these birds will visit ground feeders for seeds or cracked corn.

Although rather heavy, they are able to fly small distances but rarely do, so they work well as backyard birds.

Many people simply enjoy watching their backyard birds.