Canaries were used extensively in the 19th century, to warn miners that their lives were in danger. Upon removing coal from a seam, methane gas, or firedamp, often escapes into the air. Methane becomes combustible when its quantities comprise 5-15 percent of the air, but in the presence of coal dust, that number is reduced to 2-5 percent. It was necessary for miners to be weary of methane, because the slightest spark could ignite the gas, causing an explosion.
The dangerous nature of methane gas could not be overlooked. Colourless, odourless and undetectable to men without technology, miners had no choice but to devise a test for build-ups of methane gas. In an attempt to protect themselves, workers often kept caged canaries in the mines. More sensitive to gas than humans, the canaries would die if noxious gases were present in quantities beyond their ability to cope. Thus, miners knew that if they came upon a dead canary, it was time to head for open air.
By the time Alberta and
British Columbia’s coal industry started, safety lamps had
replaced canaries as a firedamp indicator. However, the bird
still had its uses, and firebases continued to carry the canary
to detect other harmful gases, such as afterdamp, a combination
of carbon monoxide and carbon dioxide that replaces oxygen in
the air. Budgies faint when exposed to afterdamp, indicating the
presence of gas before it reaches excessively dangerous levels.
Once exposed to clean air, the budgies can be revived.