The Lake Stymphalus by his arm was freed,
From those dire birds on human flesh who feed,
By Pallas' aid the dreadful race subdued,
No more its banks with whitening bones are strew'd.
Honour'd by all mankind he now returns,
But still Eurystheus' envious hatred burns.
Stymphalian Birds were man-eating birds with claws of brass and sharp metallic feathers they could launch at their victims, and also they were Ares' pets. Furthermore, their dung was highly toxic. They had migrated to Lake Stymphalia in Arcadia to escape a pack of wolves, and bred quickly and took over the countryside, destroying local crops and fruit trees. Ridding the land of these birds was one of Heracles' Twelve Labours, and some sources claim the Stymphalian birds were the same avians that attacked the Argonauts.