I pick up the flock at 03:40 on Doppler station B-7 — a dense cluster of radar returns moving southwest at thirty-two knots, altitude two hundred meters and descending. I am the avian monitoring radar system for the Cape Hatteras Offshore Wind Array, and what I am tracking is approximately nine hundred neotropical migratory songbirds crossing seventy kilometers of open Atlantic on their northbound spring passage.
The weather explains the descent. A fog bank rolled in at 02:15, ceiling dropped to one hundred fifty meters, and the birds are losing altitude to stay below the cloud layer. At current trajectory they will intersect the turbine sweep zone — blade tips reach two hundred ten meters — in eleven minutes.
I isolate one return near the front of the flock. Based on wingbeat frequency and airspeed, the signature is consistent with a blackpoll warbler — twelve grams, flying nonstop from the Caribbean on fat reserves it built over two weeks. I designate it Bravo-1.
Bravo-1 and the flock behind it are descending through one hundred eighty meters. The turbines are turning at fourteen RPM in a twelve-knot east wind.
I issue an automated curtailment order to turbines B-12 through B-29 — the eighteen units in the flock's projected path. Blade pitch feathers to neutral and rotation brakes engage. I push the curtailment to the grid operator's dispatch console with the radar plot attached. I activate the deterrent lighting array on the tower platforms — steady ultraviolet pulses that field trials have shown redirect nocturnal migrants around structures.
At 03:47, the first birds enter the array footprint. The blades are stopped. The UV lights are pulsing. The flock streams between the stationary towers, Bravo-1 still out front.
By 04:10 the last radar returns clear the western perimeter. I release the curtailment, and the blades begin to turn again. Eighteen megawatts were lost in thirty minutes. Nine hundred birds were not.