A fascinating moment while observing a Cooper’s Hawk on a rooftop proximate by about 75 meters to the peregrine falcon nest box located in the Clock Tower.  The Cooper’s Hawk was perched on the edge of the roof.  Without much verbal warning the peregrine strafed to Cooper’s at first and then went into a more direct attack mode next round.  Found this description from Cornell Birds of North American Online:  “Cade’s model, with nesting cliff as center, in general seems fairly accurate: series of threshold perimeters surround eyrie with decreasing defense as distance from eyrie increases. Inner perimeter may be only 200 m; within that, attacks always occur. In outer perimeter, attacks only occur over food or favored perches.”  Now that Cooper’s hawk has been put on notice!