For every action,
there is an equal and opposite reaction.
– The Physics Classroom
The equality might be tough to measure, but the oppositeness seemed obvious, anyway.
As we watched about 10,000 sandhill cranes at Whitewater Draw in SE Arizona, our attention was drawn by a northern harrier — maybe a male and a female, judging by the colouring – hunting over the marsh.
Hunting for what, you ask? I dunno, but the ducks evidently thought they might be on the menu. At some point the harrier tripped their proximity alarms and boom! They were outta there! Mid-slurp, in some cases.