# canary in a coal mine

idiom

Source: https://englishreference.com/idiom/canary-in-a-coal-mine
Updated: 2026-08-10

## Meaning

Something whose sensitivity to adverse conditions makes it a useful early indicator of such conditions; something which warns of the coming of a greater danger or trouble by a deterioration in its health or welfare.

## Examples

- Rising prices are the canary in a coal mine for the economy.
- The sudden drop in local sales acted as a canary in a coal mine, warning the company of a larger financial crisis.
- The rapid decline of the local bee population served as a grim canary in a coal mine, signaling that the entire ecosystem was facing an irreversible collapse.

## Origin

The term refers to the nineteenth- and early twentieth-century practice of carrying caged canaries into subterranean tunnels. The birds, possessing a higher respiratory rate and greater sensitivity to airborne toxins than humans, served as a primitive biological alarm. If carbon monoxide or other lethal gases accumulated within the mine, the bird would succumb to the atmosphere before the miners were affected. The death of the canary provided a window of time for the workers to exit the tunnels immediately, the bird having performed its final service to the industry.

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