Two short moments sit side by side here, and the poem lets you work out how they connect. The first is a small, almost riddle-like statement: a bird is the beginning of many leaves. The word "leaves" can mean the green leaves of trees, but it also means the pages of a book. So a bird seems to be where both nature and writing begin, as if every page starts with something that flies.
In the second part, the speaker gets a book of blank paper and, in the same moment, sees a wing "sunk in a field." The wing looks like a bird that has fallen or settled into the grass, yet it also resembles a white page lying open. The title, which blends "ornithology" with "writing," points toward this idea of birds as a kind of script.
The speaker sounds quietly attentive, more curious than sad. The mood is hushed and spare, with a gentle sense of wonder at how a blank page and a bird in a field can seem to be the same thing.