King Eurystheus gave Heracles his 6th labor and his labor was too chase away the birds which infested the Stymphalin lake.
Heracles had to get the birds out of the nest and away from the Styphanim lake.
The birds had braze feathers that they would drop from high heights and then the feathers would fall down like arrows and kill or hurt people. They also had sharp claws that could hurt people
The hard part of the labor was that the birds were nested among the reeds at the end of the lake.
Heracles held his shield to hold off the arrows the birds were dropping from above and their sharp claws. The after he took out his bow and arrow and killed each bird one by one
The bird flew away from the lake and to far out unexplored seas. then the lake of Stymphalus was deserted. When Heracles returned from the lake king Eurysthes as a favor to king Minos sent Heracles on his seventh labor