Or in sleep rehearse perfect kills and eat.
The convenience of the high trees!
The air's buoyancy and the sun's ray
Are of advantage to me;
And the earth's face upward for my inspection.
My feet are locked upon the rough bark.
It took the whole of Creation
To produce my foot, my each feather:
Now I hold Creation in my foot
Or fly up, and revolve it all slowly -
I kill where I please because it is all mine.
There is no sophistry in my body:
My manners are tearing off heads -
The allotment of death.
For the one path of my flight is direct
Through the bones of the living.
The hawk has a callous view of the world. The broken line conveys violence and speed of attack. Its ‘manners’ is an ironic comment, an  oxymoron , as killing and good manners are mutually exclusive. 
 Note also, the  terminal caesura  could resemble the quick beheading of the hawk’s prey
Hawk Roosting