The use of imagery in "A Bird Came Down the Walk" helps the reader see the bird as the speaker sees it -- living and reacting to its environment. Reading the poem you will find effective use of imagery as it displays the behavior of the bird:"He bit an Angleworm in halves/ And ate the fellow, raw." Another example of this imagery is "And then hopped sidewise to the Wall/To let a Beetle pass."
The action words "bit an Angleworm in halves" paints a vivid picture and suggests the stillness the reader must have to avoid interrupting this natural process of the bird consuming its prey. Indicating the bird "hopped ... to let a Beetle pass" suggests a preference of food -- worms over beetles. This moment illustrates how life occurs right in front of the reader and implies the importance it carries with its spectator.
Metaphor and Simile
Metaphors and similes help identify one thing by relating it with another. Similes use the words "like" or "as," whereas metaphors link them directly in various ways, such as personifying inanimate objects with human qualities. In Dickinson's poem, they give insight as to how the speaker sees nature. For example, "He glanced with rapid eyes/ that hurried all around." So even before you read the next two lines, you can picture the quick movement of the bird's eyes as it studies its surroundings. Once you read, "They looked like frightened Beads, I thought --/He stirred his Velvet Head," you find the use of the simile "like frightened Beads" to specify the birds' potential reason for its action. The bird's head is not literally made of velvet, but the simile illustrates it as smooth, silky and perhaps red or blue in color.
This poem will strike the reader with a particular mood and give clear insight to the tone of the piece. The tone of Dickinson's poem has a gentle and respectful demeanor regarding nature. As the reader, you experience the bird in the first person: "Like one in danger, Cautious, I offered him a Crumb/ And he unrolled his feathers/ And rowed him softer home --/ Than Oars divide the Ocean,/ Too silver for a seam --."
The attention to detail carries a tone of admiration and awe in the aesthetic sense. The reader clearly delights watching the motion of the bird initiating flight as Dickinson compares the bird's wings to oars. Dickinson pleasantly describes the wings as smoother, more effortlessly able to cut into the wind than oars dividing the ocean.
The theme of nature leads to great symbolism. The speaker encountering the bird has a relationship with nature, and when analyzed as allegory, it can suggest a deeper theme to this poem. Consider another poem by Dickinson called, "God Gave a Loaf to Every Bird." In it, you find the word "crumb" as something offered by God: "God gave a loaf to every bird,/ But just a crumb to me;/ I dare not eat it, though I starve,--."
Just as in "A Bird Came Down the Walk," you can replace the speaker as God, and the speaker, as the bird. Suddenly, the theme of nature reveals another layer of the author's take on God.