https://www.sparknotes.com/poetry/dickinson/section5/
Summary
The speaker describes once seeing a bird come down the walk, unaware that it was being watched. The bird ate an angleworm, then “drank a Dew / From a convenient Grass—,” then hopped sideways to let a beetle pass by. The bird’s frightened, bead-like eyes glanced all around. Cautiously, the speaker offered him “a Crumb,” but the bird “unrolled his feathers” and flew away—as though rowing in the water, but with a grace gentler than that with which “Oars divide the ocean” or butterflies leap “off Banks of Noon”; the bird appeared to swim without splashing.

Form
Structurally, this poem is absolutely typical of Dickinson, using iambic trimeter with occasional four-syllable lines, following a loose ABCB rhyme scheme, and rhythmically breaking up the meter with long dashes. (In this poem, the dashes serve a relatively limited function, occurring only at the end of lines, and simply indicating slightly longer pauses at line breaks.)

Commentary
Emily Dickinson’s life proves that it is not necessary to travel widely or lead a life full of Romantic grandeur and extreme drama in order to write great poetry; alone in her house at Amherst, Dickinson pondered her experience as fully, and felt it as acutely, as any poet who has ever lived. In this poem, the simple experience of watching a bird hop down a path allows her to exhibit her extraordinary poetic powers of observation and description.

Dickinson keenly depicts the bird as it eats a worm, pecks at the grass, hops by a beetle, and glances around fearfully. As a natural creature frightened by the speaker into flying away, the bird becomes an emblem for the quick, lively, ungraspable wild essence that distances nature from the human beings who desire to appropriate or tame it. But the most remarkable feature of this poem is the imagery of its final stanza, in which Dickinson provides one of the most breath-taking descriptions of flying in all of poetry. Simply by offering two quick comparisons of flight and by using aquatic motion (rowing and swimming), she evokes the delicacy and fluidity of moving through air. The image of butterflies leaping “off Banks of Noon,” splashlessly swimming though the sky, is one of the most memorable in all Dickinson’s writing.