Sentence:  In the meantime the pack, maddened by failure and ravenous from the view of food denied, had resumed the trail of the man. They were different beings now from the wary <WSD>skulkers</WSD> who had been following him from afar. 
Meaning of the word marked with <WSD> tags:  One who moves in a stealthy or furtive way; one who comes or goes while trying to avoid detection.