All I know is that FPS has jurisdiction on all federal property, and they are willing and eager to help out the NPS (and me) if we need them to. However, since we haven't called on them in the four months I've been here, I don't know anything else. They're good people and it's nice to know they'll come give me a hand if I've got crap going on at 0400 when I'm the only ranger on and the local PD can be kind of touchy when we call them for assistance.
In life's small things be resolute and great
To keep thy muscle trained: know'st thou when Fate
Thy measure takes, or when she'll say to thee,
"I find thee worthy; do this deed for me?"
Nemo me impune lacessit.