Did you try Tufts University - they have a wildlife rehab place out in Grafton? I know they take injured birds of prey.
I found a dead redtailed hawk when I was living in western MA - called the local EPO and he asked me to bag it and bring it over to his house. I did that so he could autopsy the bird.
There aren't enough game wardens/EPOs in the area. It is a thankless job. You run the risk of getting killed/shot at when you break up a party out in the middle of the woods.
If no one comes soon - put the bird out of pain (if it looks like it is suffering). If you can't do it let me know.