How does the motif of the mockingbird imagery show good and bad in To Kill A Mockingbird?

The mockingbird is a songbird that does not hurt anyone or burden anyone's gardens. As Miss Maudie says, "Your father's right. . . Mockingbirds don't do one thing but make music for us to enjoy. . . That's why it's a sin to kill a mockingbird" (90). Hence, mockingbirds bring songs of happiness and joy without harming anyone or anything else—they represent the innocent and good in life. As a result, they are weak and vulnerable to air-rifles and predators, which is bad. Anyone or anything out to kill a mockingbird obviously has the upper hand in the situation and can hurt the bird anyway they choose. By teaching Jem and Scout not to shoot mockingbirds, Atticus also teaches them to respect nature and never hurt anything weaker than they are.

Unfortunately, other people in the community are bad enough to hurt mockingbirds. For example, the symbolism behind this motif can be compared to Mr. Ewell being bad enough to hurt Tom Robinson, Jem and Scout. In this scenario, Mr. Ewell is more powerful against Tom Robinson (who is symbolized by the mockingbird) because he is white, Tom is black, and a white man's word trumps that of a black man's in the segregated South. Also, Jem and Scout are like mockingbirds on the night that Mr. Ewell attacks them after the school festival. He is more powerful than the kids because he is bigger and stronger, and he has both the element of surprise and a knife.

Another way we see bad with the mockingbird imagery is when the Cunningham lynch mob comes for Tom Robinson while he's in jail. Tom, again, is like the innocent mockingbird, caged and vulnerable, and predators come to take him away to hang him. If it weren't for the children and Atticus being there (protectors of mockingbirds) they may have succeeded in "shooting a mockingbird."

Another example of the mockingbird motif, as good faces off with bad, is when Tom tries to flee prison by climbing over a fence. He is shot by the guards and dies. The guards say that he was so fast and strong that he would have made it if his left arm hadn't been crippled. B.B. Underwood writes an editorial about it in his newspaper after the trial of Tom Robinson which Scout summarizes as follows:

"Mr. Underwood didn't talk about miscarriages of justice, he was writing so children could understand. Mr. Underwood simply figured it was a sin to kill cripples, be they standing, sitting, or escaping. He likened Tom's death to the senseless slaughter of songbirds by hunters and children, and Maycomb thought he was trying to write an editorial poetical enough to be reprinted in The Montgomery Advertiser" (241).

Thus, there seem to be three parts to the mockingbird motif: First, the innocent, vulnerable mockingbirds, then the hunters who are bad and kill them, and finally, the good people who don't kill them and try to stand up to protect their lives.