In Susan Glaspell's play, Trifles, why didn't Mrs. Hale and Mrs. Peters reveal their discovery of the dead bird?

In Susan Glaspell's play, Trifles,
Mrs. Hale and Mrs. Peters are very careful not to reveal the dead canary that they find
in Mrs. Wright's sewing basket.

The two women have come to
the scene of Mr. Wright's alleged murder to gather a few things for Mrs. Wright, who is
being held in the jail, accused of killing her husband. While the women are there, they
go through the kitchen and living area to find things that might be useful to Mrs.
Wright. They do not know her, though as their time passes in that sad and dark home,
Mrs. Hale wishes she had made more of an effort.

As the
women work to complete their task, they listen to the men who are totally unsympathetic
of a woman's plight in the world: the hard work needed to keep a home, extra work
created by thoughtless husbands, the difficulty in providing a home with a cheery
atmosphere; and, jarred jellies broken due to the cold. The men refer to a housewife's
worries as "trifles." The men are particularly uncaring about the life of the woman
they have decided is guilty.

Upon
further discussion between them, the women realize that without children, Mrs. Wright's
home and life must have been barren indeed. They remember her as a
vibrant, pretty young woman who used to sing in the church choir before she married Mr.
Wright. (And it is probably no mistake, with irony included, that her husband's name is
"Wright," for he has been anything BUT "right.")

The women
find a birdcage in a cupboard, stored away, which puzzles them. They believe a bird
would have made the house a happier place, providing companionship for the housewife.
When they discover the dead bird in a little box in Mrs. Wright's sewing basket, its
neck at an irregular, unnatural angle, it does not take much for them to realize that
Mrs. Wright had saved the dead bird to bury it, and that it had not died a natural
death. They surmise that Mr. Wright must have killed
it.

Their sense of compassion is heightened. Mrs. Peters
remembers losing a baby, and how devastating it was especially because she had no
friends their to comfort her. She also recalls a little boy, when she was young, who
killed a kitten before her eyes—she blurts out that she could
have...killed him! The women believe that when Mr. Wright killed
the bird, the only bright spot in Mrs. Wright's harsh and lonely world, that she lost
her mind and killed her husband while he slept.

The pair of
housewives hide the evidence of the dead bird: they believe that if they let the men
know of its existence, it will provide them with a motive for Mrs. Wright's "alleged"
murder of her husband. In the face of the total lack of concern the men show for the
plight of women such as themselves, the women unite in their purpose to protect Mrs.
Wright as best as they are able.