Osprey group name
If you're classifying these birds for science or research, flock is an appropriate term.
If you want to delve into literature and history, there are various names for a group of hawks such as a boil, cast, kettle or lease.
Learn more about ospreys and how you can conserve them at the Cornell Lab of Ornithology: https://www.allaboutbirds.org/guide/Osprey/overview
Check out OSU's webcam on an osprey nest located in the Andrew's forest: http://webcam.oregonstate.edu/osprey/
Thank you! I got another possibility from Multnomah Co. Library via a Florida Audubon group that a “group” of osprey is a duet. Obviously, these birds do not flock although a family is a group. And since a “group” of hawks is kettle, that was suggested as well. They thoroughly enjoyed the question!