Where there are shifters, you're going to get hunters. Hunters can be
human, or another supernatural race, and their only focus is on eliminating as many shifters as possible. Of course the werewolf communities try to
take care of these problems, but they have been showing up more and
more frequently as communication and knowledge becomes so widespread and easy to transmit to a large audience.
Hunters do what they do for a variety of reasons. Religious fervor, inter-species squabbling, or the sheer sport of it. The reason varies heavily depending on the individual, but the motivation is there.