Susan Glaspell weaves a murder mystery that stumps the men within the story but the wives are able to piece together the details. One such detail is the canary.To understand what the canary has to do with the story you have to look at what it represents and how the bird was killed.
The bird represented the only joy in Mrs. Wright’s life, songs and singing. Mrs. Hale said, “She used to sing real pretty herself.” The canary’s singing represented Mrs. Wright’s love of music. Both Mrs. Hale and Mrs. Peters realize that Mr. Wright was not the kind of person to appreciate music or songs. Mrs. Hale noted, "’No, Wright wouldn't like the bird,’ she said after that—‘a thing that sang. She used to sing. He killed that too.’ Her voice tightened.” This gives the reader insight into Mr. and Mrs. Wright’s home life. The strained relationship between a husband and wife.
Next, you have to look at how the bird died. Mrs. Hale almost in shock says, "Look at it! Its neck--look at its neck! It's all--other side to." This suggests that Mr. Wright wrung the bird’s neck. Literally and figuratively killing music in the Wright house.
Knowing that that Mr. Wright was choked when Mrs. Peters said, "Killing a man while he slept--slipping a thing round his neck that choked the life out of him along with the fact that bird represented music and joy for Mrs. Wright and that its neck was wrung tells the reader that Mrs. Wright killed Mr. Wright. Though this is so obvious to the reader, the men in the story do not see the small details, such as the dead bird, and are unable to solve the murder.