What do you think the bird that has made her nest in the cactus symbolizes? What do Turtle's "hidden scars" (her broken bones) symbolize? How is the name "April" significant?

These are a lot of questions for one space. You need to ask them separately. I'll take your first one. A recurring motif throughout The Bean Trees, as demonstrated by its title, is nature; there are numerous examples in which characters reference or notice the growth of plants or the occurrence of natural phenomena. The fact that birds can make a home even in the most inhospitable place, a Cactus, gives hope to these displaced women.