WARNING: This article contains spoilers from Monster: The Ed Gein Story
Netflix's latest sensation, Monster: The Ed Gein Story, has been gripping viewers worldwide since its release on October 3, reports the Manchester Evening News.
The series boasts a cast of real-life characters, including Ilse Koch (portrayed by Vicky Krieps), Psycho star Anthony Perkins (played by Joey Pollari), and Adeline Watkins (brought to life by Suzanna Son), among others.
This third instalment of Ryan Murphy's true crime anthology series also features notorious serial killers such as Ted Bundy (John T. O'Brien) and Richard Speck (Tobias Jelinek).
However, many are curious about the enigmatic Birdman.
Who is the Birdman in Monster: The Ed Gein Story?
The series shows Speck exchanging letters with Ed Gein (Charlie Hunnam), discussing his prison experiences and citing the Plainville Ghoul as his muse.
Speck also refers to the Birdman, another real-life serial killer, better known as the infamous American criminal Robert Stroud.
Convicted murderer Stroud killed a bartender and attacked fellow inmates and guards while incarcerated. In 1916, he murdered a prison guard and was sentenced to death, but this was commuted to life imprisonment in solitary confinement.
He earned the monikers 'Birdman' and 'Birdman of Alcatraz' after caring for a nest of three injured birds he found in the prison yard during his time at Leavenworth.
After a couple of years, he'd accumulated 300 canaries and would go on to conduct research and pen the book Diseases of Canaries, published in 1933.
He was permitted to continue his pastime because it was deemed a constructive use of his time, according to Alcatraz History.
Stroud carried on investigating avian ailments and documenting their behaviour and anatomy, even marketing treatments for them.
However, his apparatus and bird studies came to an abrupt halt when it was discovered he'd been utilising his equipment to brew alcohol on the side.
In 1942, Stroud was relocated to Alcatraz, where he would remain for the subsequent 17 years of his existence.
In 1959 Stroud was transferred to the Medical Center for Federal Prisoners in Springfield, Missouri and passed away four years later in 1963 of natural causes.
He was immortalised on the silver screen by Burt Lancaster in the film Birdman of Alcatraz, which secured the star an Oscar nomination for Best Actor.
Fascinatingly, the reason Speck may have also referenced Birdman was due to his own encounter with a sparrow whilst incarcerated, which earned him a similar moniker among the inmates.
According to Mindhunter FBI Agent Robert Ressler's book Whoever Fights Monsters, Speck captured a sparrow and kept it as a companion.
When he was cautioned by a prison guard that he'd be placed in solitary if he didn't free the creature, Speck killed the bird by hurling it into an overhead fan.
The astonished guard enquired why Speck had committed the brutal act, to which the serial killer was reported to have said: "[B]ut if it ain't mine, it ain't nobody's."
Monster: The Ed Gein Story is streaming on Netflix now
