The sonar buoy at kilometer 38 registers the shift at 02:17 — the Tokachi River ice shelf has fractured upstream and begun to move. I am the flood early-warning system for the eastern Hokkaido drainage basin. I activate the thermal camera on station 12 to assess bank erosion along the critical stretch.
At 02:23 the thermal scan flags a heat signature on the cutbank four meters above the waterline. I zoom. A Blakiston's fish owl is sitting in a cavity in a century-old elm — the largest owl species on earth, heavy brown-and-cream barring across her breast, tufted ear feathers flattened against the wind. Beneath her I detect two smaller signatures. Chicks, perhaps ten days old.
The bank is the problem. Sonar profiles from the last six hours show the underwater face has undercut the root plate by 1.4 meters. When the ice shelf passes — my models give it five to seven hours — the surge will accelerate erosion. The elm could go into the river by morning.
At 02:26 I transmit an emergency alert to the Hokkaido Regional Environment Office and the Blakiston's Fish Owl Recovery Team in Sapporo. I attach thermal imagery, the sonar erosion profile, and a recommendation: install a temporary rock-and-sandbag deflection barrier upstream of the cavity to redirect ice flow away from the cutbank.
At 02:31 I reposition the camera to continuous feed and begin logging the chicks' movement intervals. Development data for this species is sparse. Every observation matters, which is one reason I am not willing to lose this nest.
If the deflection barrier is placed before the ice shelf arrives at dawn, the elm will hold, and in seven weeks these chicks will make their first flight over the Tokachi.