Canaries in a coal mine? It's more than a metaphor, and it preceded the first 'bring your pet to work day' of the 21st Century. It's a scientific fact that coal miners use to carry caged canaries into their coal mines for security purposes. If there was any methane or carbon monoxide emanating from a mine, the canary would die before the gas reached the hazardous levels most harmful to humans.
Common Lore Became A Warning
The idea of using canaries is credited to John Scott Haldane, known as “the father of oxygen therapy."
Since 1911, the practice of using a bird to test the air supply has become part of coal mining lore, but the ideology behind it has become a popular expression. The phrase "living like a canary in a coal mine" often refers to serving as a warning to others.
Canaries were used because their anatomy required more oxygen than humans -- making them more sensitive to toxic gas levels, which cannot easily be detected having no color, odor or taste.
Listen to the Birds
'Bird Box' is the new Netflix hit that dishes up a new twist to 'canaries as harbingers of danger.' Susanne Bier’s post-apocalyptic thriller was released just recently. Over 45 million Netflix accounts viewed the film in its first week out, and it quickly became a pop culture phenomenon on social media, inspiring a countless number of memes.
In the movie, Sandra Bullock plays Malorie, one of the survivors of a mysterious threat that caused people to kill themselves after gazing upon a monstrous creature. According to a Indie Wire review, "there’s not much logic to it, and a handful of people appear to not just be immune, but also disciples of these creatures." The threat seems hopeless until Malorie is the first to discover a secret weapon to counter the phenomenon -- namely birds!
Just as the canaries were once the early indicators of danger, in the film, three birds that Malorie finds in an abandoned supermarket are quick to squawk when one of these mutants or its disciples begin to display their malicious intent.
So without too much more insight that might turn this review into a spoiler, my suggestion is to view and analyze this unique plot twist for yourself. In fact, if it gets too intense you just might want to take heed from the characters in the movie and cover your eyes, or at minimum, watch it with one of your pet birds close by -- and report back.
Primary Source: Indie Wire