The birds guard Ares' Temple, currently the Intrepid Sea, Air & Space Museum. Phobos summons them to fight Clarisse La Rue after he and his brother Deimos steal Ares' War Chariot from her. Clarisse fights them outside Goode High School, the school that Percy Jackson was attending, and he sees that she is fighting a losing battle. He leaves class, with the excuse of being sick to help her, and together they successfully fight off the birds.
They are made of metal, have black feathers, and are the size of ravens.
- They have razor sharp feathers that can be used as arrows.
- Their feathers are not lethal but can leave marks and bruises.
- The birds are extremely hard to fight off, as they attack in swarms.
- They are often called the Stymphalian Bird.
- They guard the sacred Amazon shrine, Ares' Temple, in the Black Sea. They are referred to as Ornis Areios in Greek.