I worked at San Juan Island National Historical Park many years ago, right after their troubles with an exploding rabbit population. I don't know how many rabbits the owls ate, and they probably didn't cause the much-needed drop in population, but I do know they loved the voles that ran through the prairie on the south end of the island at American Camp. They used to regurgitate the pellets of bones and fur from their perch atop the flagpole. It meant that as a park naturalist you could usually find a handy source of natural history materials right around the flag area.

SRS