You mean to tell us that there might be more than just one thing trying to destroy walls? In addition to the Something alluded to in line 1, our speaker tells us that hunters are culprits as well.
However, their "work" (read: wall-destroying techniques) is very different from the Something’s wall-destroying techniques. Let’s examine.
I have come after them and made repair Where they have left not one stone on a stone,
Our speaker must clean up after the hunters.
He says, "I have come after them," instead of "I came after them," giving us the impression that this is a common occurrence.
That must not be very much fun. These hunters are like 4 year-olds – they play all the time, but they don’t pick up after themselves. The speaker follows like a parent or a chaperon, rebuilding the parts of the wall that they destroy. Naughty hunters.
But they would have the rabbit out of hiding, To please the yelping dogs. The gaps I mean,
Little bunnies like to hide inside the wall from the hunters, and, so, in turn, the hunters tear down the wall to find them. Poor little bunnies.
However, the hunters aren’t the selfish wall-wreckers that we think they are – they’re merely trying to please their bunny-loving dogs. Wow.
Sherlock, what do you say we take a step back, and look at the characters involved in this wall mystery so far: we have the Something of line 1 (a quiet suspect), the hunters (quite noisy and destructive culprits), bunnies (innocent, little creatures just looking for safety), and dogs (who want to eat the bunnies).