Why do you think the author of this novel chose to name the book "To Kill a Mockingbird?"
When Jem acquired his first rifle, Atticue tells him to practice his aim by shooting cans. But Atticus realizes the power of the temptation to shoot at birds. He reminds Jem of the old saying that "it's a sin to kill a mockingbird. From the e-notes study guide: "As Miss Maudie Atkinson explains, it would be thoughtlessly cruel to kill innocent creatures that 'don't do one thing but make music for us to enjoy.' "
The title also carries a strong symbolic meaning. When Tom Robinson is shot trying to run away, his violent death is compared to "shooting a mockingbird." He did nothing wrong but only tried to help Mayella Ewell. Although the deputies were legally justified in shooting an escaping prisoner,, they shot him 17 times, intent to kill.
Later, when Sheriff Heck Tate decides not to investigate Bob Ewell's death (stating instead that Ewell fell on his own knife), he says that it would be merciless to subject Boo Radley to the limelight. He said that all the women in Maycomb, including his wife, would be bringing cakes to the shy man's house--something that would be cruel to a recluse. When Atticus asks Scout if she understands, she says that bringing that attention to Boo would be "like shooting a mockingbird." Boo only helped the children with his little attentions and then, ultimately, by saving their lives.
So symbolically, both Tom Robinson and Boo Radley are "mockingbirds," and the title takes on this deeper resonance.