Juvenile eagles are easily distinguished from adults by their dark plumage and dark beaks. In their fifth year, juveniles molt into the traditional white head and tail plumage, but their heads are still streaked with brown around the eye and the tail has a dirty band along the trailing edge. Using these variations in plumage, and noting missing wing and tail feathers, we can almost identify our eagle visitors individually. Of course, the murres and the other seabirds don't particularly care how many different eagles are around. It's the same to them whether one eagle flies by the nesting area six times or six eagles fly by once each.
Murres nest in groups and the larger the group, the safer the individual.
A predator can only grab one murre at a time, leaving the others shaken but safe. But cliff tops are large and more accessible than the crevices, making them eagle magnets. Last year, we actually witnessed an adult eagle land at Petcol and make a meal of three hapless chicks. Raptors dining on adult murres is one reason the population is declining. However, it's not the major one.