Creature record / 1948

The St. Louis and Alton Giant Bird Flap (Thunderbird Sightings), 1948

April 1948 · Alton, Illinois, and greater St. Louis, Missouri, with a separate cluster around Caledonia and Freeport, northern Illinois, United States

28Thinly documented Cryptid Creature 14 sources 4 videos

April 1948. A retired Army Air Forces colonel stood near Alton, Illinois, and watched something cross the sky. He thought his eyes had failed him. They had not. "It was definitely a bird, and not a glider or jet plane." Within weeks the reports multiplied. A farmer in Boone County. Two St. Louis police officers on a Saturday night. A resident of Russell Boulevard who saw a big dark thing chasing a plane. A father and son in Alton who compared its body to a naval torpedo. Newspapers called it a bird as big as an airplane. Project Sign filed it. J. Allen Hynek later reclassified it as "bird." Decades on, it became the opening chapter of the modern Thunderbird legend.

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Key facts

When	April 1948
Time of day	various; the St. Louis police sighting was on a Saturday night
Where	Alton, Illinois, and greater St. Louis, Missouri, with a separate cluster around Caledonia and Freeport, northern Illinois,United States
Duration	weeks (a flap from early April into May 1948)
Witnesses	15
Witness roles	police,military
Found
Evidence	none confirmed
Investigations	Project Sign Incident 123 (USAF),Project Grudge review (Hynek reclassified as bird),St. Louis mayor's office capture attempt (Charles Hertenstein)
Status	undisputed

The creature

A giant bird "as big as an airplane", dark or grayish-black, with a body like a naval torpedo and a wingspan put at over 20 feet. Some saw slow, lazy wingbeats; Siegmund saw none. It flew at several hundred feet, cast a shadow like a Piper Cub's, and once seemed to chase a plane.

Size	about 6 m (wingspan over 20 ft (Overland witnesses))
Altitude	about 150 m
Colour	black, grey
Surface	dark
Motion	pursued or followed

The Lawndale Thunderbird Attack on Marlon Lowe (related)

Context

April 1948. America was in its second spring of flying saucers, the era that followed Kenneth Arnold's sighting. Then newspapers in Illinois and Missouri began carrying a different kind of report. Not a disc. A bird "as big as an airplane."

Sources (14, most influential first)

The Mythic, Child-Stealing Thunderbirds of Illinois · Atlas Obscura· 2015-08-05 · Press, book, documentary · news
The UFO Flap of April 1948 · The Saucers That Time Forgot (Curt Collins)· 2019-03 · Wiki, blog, podcast · blog
Thunderbird (cryptozoology) · EBSCO Research Starters · Press, book, documentary · other
Giant Thunderbird Returns · Frontiers of Zoology· 2014-04 · Wiki, blog, podcast · blog
1948 Giant Bird Mystery in St. Louis · UN-X News (Margie Kay)· 2020-12 · Wiki, blog, podcast · blog

Reputability

28/100Thinly documented

Editorial note: most sources for this case are later retellings; the press and book coverage is thin.

Keywords

People

Walter F. SiegmundRetired colonel, former commandant of Camp Kearns Army Air Forces base; witness near Alton, 4 April 1948
Francis HennellySt. Louis police patrolman; witness, 24 April 1948
Clarence JohnsonSt. Louis police corporal; witness alongside Hennelly
Kristine DolezalWitness on Russell Blvd, St. Louis, who saw the bird "chasing the plane"
Robert PriceBoone County farmer; witness at Caledonia, Illinois, 6 April 1948
J. Allen HynekReclassified Project Sign Incident 123 from unidentified to "bird"
Loren ColemanAuthor of Curious Encounters, which framed the flap as the start of the modern Thunderbird wave
Curt CollinsResearcher who compiled the 1948 newspaper clippings on The Saucers That Time Forgot

Names

J. Allen Hynek Loren Coleman Brad Sparks Kenneth Arnold Project Sign Project Grudge thunderbird Curt Collins Lawndale