Mining has always been a risky profession, but in the early 20th century, it was even more dangerous. A report published by the Centers for Disease Control and Prevention (CDC) shows that “the period 1900 through 1909 was the deadliest decade in U.S. underground coal mining,” with 3,660 miners dying in over 100 incidents around the country. In comparison, “only” 7,946 miners died between 1910 and 2006.

Canary Connection

Part of the reason for that lower number was the introduction of canaries in coal mines in 1911. The idea of using canaries in mines comes from British physician John Scott Haldane, whose research into gases and their effects on people earned him the nickname of “the father of oxygen therapy.” Haldane invented one of the earliest gas masks and researched decompression sickness, but one of his main interests was understanding what caused so many mining disasters.

John Scott Haldane

John Scott Haldane. Via Wikimedia Commons.

His suggestion? Put a canary in a cage and bring it to the mine with the workers. Canaries are extremely sensitive to carbon monoxide, have a high metabolism, and need large amounts of oxygen to survive — so if the bird suddenly became ill or died while inside the mine, miners would have enough time to evacuate before the poison could affect them as well.

It wasn’t long until canaries became a staple in mines in the UK, Canada, and the U.S.

The Bird Box

Earlier mine canaries likely succumbed to poisoning but scientists soon came up with a more humane solution: the canary resuscitator.

This special birdcage had three walls of solid glass and a wall made with a grill wall filled with ventilation holes. If the bird fell from its perch (a sign of poisoning), the miners could close an airtight door over the holes and open the vials of oxygen installed on the roof of the cage. This was enough to revive the canary as the miners escaped, cage in hand.

Soon, the canary became a beloved underground companion, with anecdotes of miners “whistling to the birds” and interacting with them. Not a surprise, as the colorful birds probably saved thousands of lives over the next few decades.

And Your Bird Can Sing

Canaries were officially retired from mining work in 1986, when a digital detector known as the “electronic nose” was introduced. The sensor could detect not only carbon monoxide but also other gases.

In addition to being cheaper to use, the sensors were also more accurate, could detect pollutants earlier than animals, and saved animal lives  – by detecting the presence of poisoning gases sooner, it allowed workers enough time to also evacuate ponies (used to haul coal) from the mines.

Luckily for everybody, the canary-in-the-coal-mine cliché is now ancient history.

By Diana Bocco, contributor for


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