It means that the fish hawk are cunning and gothic and can see everything more like a fox
The persona in "To His Coy Mistress" is basically a guy coaxing his lady love to "do it" with him using arguments of time and mortality. While this concept of convincing a woman to "give it up" is timeless, in this poem it is rather clear how the persona sees women as objects for pleasure. His persuasion, while flowing with cadence, reeks of machismo typical of predominantly patriarchal age.
