They resembled owls. By temporarily trading bodies with humans, the Stikini manifested a physical form on Earth at night through the energy of a "decent number" of dreaming humans nearby to so they could hunt for human and stag hearts.
In 1880, the Stikini chief Malatche made a pact with the Seminole medicine woman Totika to swap the bodies of her own people with the Stikini. She believed that they would devour the Anglos that caused her suffering to face justice, but the Stikini were simply using her psychic abilities as a permanent tether to Earth so they could escape the Red Skies. In the Indian Territory on Earth, Totika summoned the Stikini to kill the outlaws Seth and Frank Shelton as a means of them facing justice. Totika successfully performed a ceremony to swap Bill Potts with Malatche's wife, the War-Queen Cocheta, but Bill, along with the trapped Seminole, were able to will themselves out of the Red Skies, forcing the Stikini back to where they came from. After being returned to the Red Skies, something burnt all the Stikini to death. (COMIC: The Parliament of Fear)