Your welcome.
From what I can see, someone coming over the border illegally cannot be assumed to be committing a felony under federal law until they can be proven to be "alienated", or re-entered after being previously deported, and someone observing illegal entry would have no way of ascertaining that at the time. So Arizona law regarding the requirement of the observation of a felony in order to facilitate a citizens arrest would not be in force
That would be my understanding, also.
but trespass could apply under state law. But the border groups are well within their rights to report suspected illegal aliens to the INS
Yes, and that is were the majority of these groups operate, on private property. Once they move to public land, they now walk a very thin line. They can however, follow and report the suspected illegal activity to the Border Patrol.
are there any guidelines or programs that you know of that encourage such?
Not that I know of. The Government would never start a program for civilians that helps enforce laws they do not want enforced.
Let me rephrase that - are there programs that encourage private citizens to report suspected illegal alients?
Thanks for the clarification. If any members of these groups are following this, in my lay opinion I concur with Marine Inspector regarding the differences between action on private land and action on public land.