Hugh Powell explains how cannon nets work and what can go wrong with them in “Twinkling the Whimbrels.”
Cannon netting consists of firing three projectiles over a flock of birds, trailing a single net that traps the birds underneath. Setting up the cannons is a daylong process that involves digging three separate metal tubes into the ground about 15 or so feet apart and stuffing them with a long, metal projectile, each of which will carry one section of the long nylon net.
When the tubes are dug in and properly aimed, we hook each cannon into an electrical system and place black powder at the base of the cannons. Then we string a set of wires back to a control box strategically placed a couple of hundred feet away in a well-hidden vantage point. After all of that is in place, we dig a trench to conceal the net and cover it with seaweed and other detritus. Then it’s a matter of hiding and waiting for the birds to arrive. Just imagine Wile E. Coyote trying to catch Roadrunner with a big contraption triggered by TNT in the old Looney Tunes cartoons.