Symbolism, Imagery, Allegory
We go to Maya Angelou when we to find out why the caged bird sings, but we head to Susan Glaspell when want to know how the caged bird… croaked.
The dead canary and its broken cage are by far the most glaring symbols in Trifles, so we guess we'd better break them down, right? Right.
Bird = Minnie Foster
First, let's all agree that the canary represents Mrs. Wright, who used to be known to the world as Minnie Foster before she inexplicably married the biggest jerk in Dickson County. Here's a quote to prove it, in case you're not convinced:
MRS. HALE: She used to wear pretty clothes and be lively, when she was Minnie Foster, one of the town girls singing in the choir. But that—oh, that was thirty years ago. (58)
Oooh, what have we here? Pretty clothes… like pretty feathers? Lively… like a chipper bird? Singing in a choir… like a songbird? There's no doubt about it: that canary is Minnie. In case anybody forgot this line, Glaspell also include this one:
MRS HALE: She—come to think of it, she was kind of like a bird herself—real sweet and pretty, but kind of timid and—fluttery. How—she—did—change. (109)
Okay, now there's no possible way to contest it. The canary represents Minnie Foster: that sweet, fluttery girl who was transformed into the lonely, depressed Mrs. Wright by years of her husband's neglect and emotional abuse.
Cage = Sucky Marriage and Escape
All right, let's talk about this cage. If Minnie Foster is the canary, then we can definitely see how the cage could represent the stifling marriage that turned her into depressed Mrs. Wright. We know that the cranky John Wright demanded silence in his house. Add that to the geographic isolation that the remote house created, and Minnie Foster was definitely in a cage.
However, when we meet the cage, the door has been violently torn off of it. We learn that John Wright tore the door off so that he could wring the bird's neck. Ironically, though, this symbolic murder of Minnie Foster is what leads to murder of John Wright. For Minnie, it's the last straw, and it's the thing that makes her strangle her husband in much the same way that he killed the bird.
So even though the cage's broken door is a sign of Mr. Wright's penchant for bird-murder, it might also symbolize the violent way in which Mrs. Wright finally escaped her cage of a marriage. In a way, she not only murders John, the bird-like Minnie Foster also murders Mrs. Wright.