We can't get enough of our feathered friends, and neither can Jazz. Jeepers. Birdies in cages, birdies flying free, birdies that say "I love you"…
Let's start with the caged birds. We know why they sing, and it's because Violet, with all her maternal hunger, has made them a pretty little home complete with mirrors. But then, she "set them out the windows to freeze or fly, including the parrot that said 'I love you'" (1.1). Looks like somebody's had a change of heart.
You know whenever a bird and a cage shows up that it's going to be so symbolic. A bird is a creature that is supposed to fly—you know, the ultimate expression of freedom. So while they're taken care of when you put them in cages, they're also reduced to something flightless, they lose their freedom.
Huh. Might this have anything to do with slavery? Sure does. What better symbol for enslavement than trapped birds? When Violet lets her birds out, she's sending them into peril, but she's also giving them the power of flight. When the enslaved people were freed at the end of the Civil War they were allowed to go free—but the post-war South was as hostile an environment as they come. Hence the Great Migration, when thousands of black people went north in search of a less racist climate.
But birds don't only symbolize enslavement and freedom. They're also beloved pets to be nurtured—some of them even say, "I love you." So when Violet lets hers loose after Dorcas dies, we can see just how unhinged she is. She is rejecting what she holds dear, both in terms of the birds and in terms of her relationship with Joe. Her brain has also flown free of reason. Just as the birds scatter, so, too, does Violet's mind.
On the flip side, we know that all's well again between Joe and Violet when they get a new birdie. Violet is ready to care for something again, something that acts, for the childless Joe and Violet, like a child.
The bird that Violet gets at the end of the novel "wasn't well [… until] they took the cage to the roof one Saturday, where the wind blew and so did the musicians in shirts billowing out behind them. From then on the bird was a pleasure to itself and to them" (10.11). So this bird gets the best of both worlds: nurturing care and a sense of the outdoors. That sounds like good parenting, er, bird-keeping, to us. The kind someone who's completely sane would be able to pull off which, of course, is exactly how Violet is at the end.