Question: Why did they rescue the Norfolk eaglets? I thought Dad had come back and was taking care of them?
I don't officially know why, but I can imagine that it was felt that they were at risk without both parents. From observing the other eaglet family, I can deduct that:
-- It is important that one parent be close by at all times, due to other winged predators (owls, etc.)
-- I imagine it would be hard for Dad to fish and hunt while keeping an eye on the nest
-- I imagine that for eagles, having 2 parents is important for the survival of the babies
-- I would like to think that nothing can take the place of a mother's care, not even the father.
The researcher's probably did not want to risk harm or death coming to these three eaglets. Although eagles are off the endangered species list, they still need to be monitored. The researcher's will ensure they are well fed and taken care of and will probably release them into the wild at some point.
I personally applaud them for doing what they need to do. The father will be better off, too, and will undoubtedly find a new mate. It's unfortunate that mom had to die in such a tragic, freak accident.