How does the following poem exhibit a form of tunnel vision while describing nature? Turtle walking slow Moving alone on the bank Swimming in a...

The tunnel vision present is that the poem takes a moment
in nature and expands it to encompass the entire poem.  The idea of the turtle's
movements is presented a tunnel vision format, where only the turtle exists in the vast
configuration of nature.  The "walking slow" and the "moving alone" images focus the
reader's attention to only these aspects of nature.  Even the inclusion of the turtle in
a larger setting continues only the focus on the turtle.  For example, the reader does
not see much of the bank, and at the same time does the reader does bit see the stream. 
These experiences are tunnel vision for a couple of reasons.  The first is that the
entire sequence and experience of nature is concentrated into only the turtle's
actions.  At the same time, the Haiku format allows the reader to succinctly see only
the turtle, as the economy of words and syllables affords only this to be seen.  In
this, there is no other description except that of the turtle in nature, contributing to
tunnel vision on the part of both reader and poet.