
Canaries are sensitive to chemicals, including perfumes, cleaning products, air fresheners, cigarette smoke, and even candles. Due to their sensitive respiratory systems, canaries were used as a biological early warning system for detecting toxic gases in mine coals in the past.
Miners faced the risk of exposure to deadly gases such as carbon monoxide while working deep in coal mines. Since these gases are odorless and invisible, miners were unable to detect them, which made working in the mines highly dangerous.
To address this issue, underground workers started using canary birds as early warning systems. The birds were highly sensitive to toxic gases, and if exposed to dangerous levels of gases like carbon monoxide, the birds would show signs of distress, become sick or even die. The miners would then evacuate the mine immediately to avoid being exposed to the dangerous gases themselves.

The Canary in The Coal Mine:
Did you know “the canary in the coal mine” is a commonly used metaphorical phrase that refers to a warning sign of impending danger? It originated from the practice of using canary birds in coal mines as an early warning system for toxic gases.
The use of canary birds as early warning systems became widespread and highly effective in the mining industry. Miners often carried the birds in small cages with them as they worked in the mines. The birds’ presence allowed the miners to work safely and prevented many accidents and deaths that would have occurred otherwise.
However, as technology and safety measures improved, the use of canary birds in coal mines declined. Modern equipment and sensors can now detect toxic gases in the air and alert miners to the danger before any harm can be done. This has made the use of canary birds redundant in the mining industry, and the practice has become a part of history.