Its completely possible though. Looking at his "patient" wall you can see that he had been collecting for a long time. Just so happens that this time he took the female of the alpha male. Its only logical that after seeing so many of his fellow "humans" be abducted by this guy that losing his female to Neville is the final straw. edit - BTW, he comments on how they ARENT showing any human like behavior. Thats where he was wrong and it showed his ignorance.