What did Hercules do to kill the Stymphalian birds?

Hercules killed the Stymphalian birds as part of his Twelve Labors by using a pair of bronze castanets given to him by Athena. He made a loud noise with the castanets to startle the birds from their hiding places. Once they took flight, he shot them down with his bow and arrows, effectively eliminating the threat they posed to the region.