🦅4.5 Raptor Station: Field Notes From Recent Monitoring

1. Eagle Column and River Formation
   When raptors gather, they first form a thermal column ("eagle column"). After circling to gain height, they exit one by one along the outer tangent line, forming an "eagle river." This behavior relies on thermals—rising warm air—to lift them before gliding away.

2. Evening Migration Bias
   Closer to dusk, more raptors arrive from the east valley. Few come from the west. Reason: the sun heats the east valley air more intensely in the afternoon. This creates stronger updrafts, attracting raptors from that direction.

3. The "After-Hours Harrier" Phenomenon
   Harriers have a facial disk similar to owls. They possess advanced flight control and are less dependent on thermals. As a result, they continue flying after other raptors stop at sunset. Same applies to early morning—harriers are often the first active. Hence, the nickname: “after-hours harrier.”

4. Osprey Grip Mechanics and Talon Laterality
   Ospreys often fly with fish in tow. Fish are aligned head-first to reduce drag. To achieve this, the osprey's talons must hold asymmetrically—one forward, one back. Current limited data suggests left-talon dominance: left talon usually in front. Question remains—do right-taloned individuals exist? Further data may reveal.