If you set up a bird feeder in NJ, at some point you are likely to see a Cooper’s Hawk. This particular hawk makes its living mostly by hunting birds and small mammals. I have even seen 1 take out a mallard, which must to have had close to twice the hawk's bodyweight.
Cooper’s Hawks are magnificent animals but many enthusiasts do not feel comfortable playing a role in any animal’s demise. If this is an issue for you, the easiest thing to do is remove the feeder for a few days and this will likely result in the hawk looking elsewhere for its food.
It's important to keep in mind that there are no villains in the ecosystems of New Jersey. Everything needs to eat!
The predator-prey relationship can have impactful, far-reaching and non-obvious ramifications. Wildlife biologists know this as a trophic cascade which has only very recently been explored and is beginning to be appreciated. Predators actually give life to many parts of the ecosystems in which they inhabit as well as take the life of their prey. A great TED talk that I highly recommend which speaks in detail about this very subject can be found here https://www.youtube.com/watch?v=ysa5OBhXz-Q. Get out and enjoy NJ's amazing wildlife!