Final answer:
The speaker attributes the gaps in the wall to the forces of nature and hunters who disturb the stones while hunting.
Step-by-step explanation:
The speaker in Robert Frost's Mending Wall blames both nature and hunters for the gaps in the wall. The poem describes the natural process of frost causing the ground to swell, which in turn pushes the boulders from the wall, and also notes that hunters, in pursuit of rabbits, have actively dismantled parts of it to get their game. The annual repair of the wall serves as a metaphor for the maintenance required in human relationships, yet the speaker also contemplates the questionable necessity of the wall's existence.