He was focused on dealing with the big mutant rats, but he would still deal with those medium-sized rats when they were trying to block his way and jumping on him.
Of course, he also didn't forget to deal with the smaller rats whenever they were already near him when they climbed the vines that he was using to move around.
Since the rats had also become more intelligent or more conscious of their surroundings, they started to call others to deal with tougher opponents together.
He and the others, who were obviously killing more mutant rats, were the targets.
And because he wasn't on the wall like the others, there were more mutant rats bonding together to take him down, as he probably seemed to be an easier target.
He welcomes them, as he could deal with more mutant rats; however, he wanted to move around more, but since they were all gathering to gang up on him, he couldn't move as much as he wanted.
