A writer at her desk looks out the window and sees a robin building a nest. The speaker watches closely, noticing the small, physical details: the sticks and grass, the bird pressing them into shape with her muddy breast. Nearby, the robin's mate sings in a lilac that is just beginning to bud. It's an ordinary spring scene, and the speaker treats it with quiet attention.
The mood is tender but not carefree. The last two lines bring in doubt: "If fates and jays agree," the nestlings will fledge. Jays, which can threaten nests, hint at how much could go wrong. The final image, nestlings "fragile as imagined wings," suggests that the young birds, and perhaps the whole hope of the nest, are still more idea than certainty. The speaker seems to feel affection and hopefulness, mixed with a gentle worry. The poem's calm, observant tone lets both feelings sit side by side, much like the fragile beginnings of spring.