Although the legend of the Piasa Bird predates European settlement, its most popular version was recorded in 1836 by Professor John Russell of Shurtleff College in Alton. Russell recounted how, as the story goes, an aging Illini chief named Ouatoga was forced to protect his village from the monstrous bird. With no warning, the fearsome Piasa Bird appeared over the Mississippi River one day and snatched up one of the village's warriors who was out fishing; each morning and afternoon following that attack, it would return, emitting a sanity-shattering shriek to mark its arrival, and attempt to abduct another victim to hungrily devour in its lair.

Ouatoga was known to be a wise and fearless leader, but even he was at a loss when it came to defeating the Piasa Bird; the arrows of Tera-hi-on-a-wa-ka, the village's arrow maker, merely bounced off the flying beast’s scales, even when fired by the tribe's best archers. Frustrated at the creature’s seemingly invulnerable hide, Ouatoga appealed to the Great Spirit. He fasted and prayed for an entire moon until the answer came to him in a dream—the Piasa Bird’s armored flesh had a weak spot underneath its wings. Ouatoga offered thanks to the Great Spirit and called the tribe together to devise a plan.

He had Tera-hi-on-a-wa-ka craft arrowheads and paint them with poison while the tribe fasted and prayed. And then, that night, Ouatoga and six of his bravest warriors prepared an ambush atop the high bluff overlooking the river. At dawn, Ouatoga stood seemingly alone while his men hid behind a rock ledge, bows at the ready. When the Piasa Bird came that day it went straight for Ouatoga, sensing easy prey; the Illini chief bravely steadied himself, grasping the strong roots that grew out of the bluff. The Piasa Bird pierced him with its razor sharp talons and raised its great wings to escape with its latest meal, but Ouatoga gripped the roots even harder. It was then that the six warriors sprung from their hiding place and fired their poison arrows into the vulnerable spot beneath the monster's wings. The Piasa Bird struggled to carry off Ouatoga, but he hung fast, and every time the gargantuan monster lifted its wings, the warriors fired more of their poison arrows. Eventually, the Piasa Bird succumbed, and with a scream of agony released its hold on Ouatoga, its corpse plunging into the mighty river below to be lost to time.

The warriors carried their wounded leader back to the village, where he eventually regained his health. A great celebration was held, and the next day, Tera-hi-on-a-wa-ka returned to the bluff with a set of paints, and marked the cliff face with a picture of the Piasa Bird in tribute to Ouatoga and the Illini's victory. From then on, whenever a member of the tribe passed that painting, they would fire an arrow at it in salute to Ouatoga and their deliverance from the Piasa Bird.

Professor Russell did more than collect stories, and while exploring the area he found a mysterious mass grave—a find that some believe gives morbid evidence of an unknown truth behind the legend. Illinois is home to many tales of unusually large birds—often referred to as thunderbirds, after the indigenous legend most common in the American Southwest—and some of these stories even involve attacks on people. One such story occurred as recently as 1977, when three boys were accosted by a ‘thunderbird’ in the town of Lawndale. One of the boys, then 10-year-old Marlon Lowe, was said to have been carried a few dozen feet by the aggressive avian. Thankfully, he was released and no serious damage was done—the same cannot be said for the remains found by Professor Russell.

The professor recounted his experience in 1887 for William McAdams’ work Records of Ancient Races in the Mississippi Valley.

Near the close of March of the present year, I was induced to visit the bluffs below the mouth of the Illinois River, above that of the Piasa. My curiosity was principally directed to the examination of a cave, connected with the above tradition as one of those to which the bird had carried his human victims. Preceded by an intelligent guide, who carried a spade, I set out on my excursion. The cave was extremely difficult of access, and at one point in our progress I stood at an elevation of one hundred fifty feet on the perpendicular face of the bluff, with barely room to sustain one foot. The unbroken wall towered above me, while below me was the river. After a long and perilous climb, we reached the cave, which was about fifty feet above the surface of the river....The roof of the cavern was vaulted, and the top was hardly less than twenty feet high. The shape of the cavern was irregular; but, so far as I could judge, the bottom would average twenty by thirty feet. The floor of the cavern throughout its whole extent was one mass of human bones. Skulls and other bones were mingled in the utmost confusion. To what depth they extended I was unable to decide; but we dug to a depth of 3 or 4 feet in every part of the cavern, and still we found only bones. The remains of thousands must have been deposited here. How, and by whom, and for what purpose, it is impossible to conjecture.

So if you’re ever in Alton, Illinois, make sure to stop by the bluffs outside of town to see the spectacular painting of this local legend; but if you hear a terrible shriek and the beating of enormous wings, perhaps it’s best to avoid the Mississippi River that day, lest you be carried off to join the bones greedily collected by the flying nightmare that is the Piasa Bird.