From the "Sentinel species" wikipedia page.
The classic example is the "canary in the coal mine". The idea of placing a warm-blooded animal in a mine to detect carbon monoxide was first proposed by John Scott Haldane in 1895,\2]) and canaries were used as early as 1896.\3])\4])\5])\6]) Countries such as Britain, the United States, and Canada used canaries as a sentinel species.\7]) Well into the 20th century, coal miners brought canaries into coal mines as an early-warning signal for toxic gases, primarily carbon monoxide.\8]) The birds, being more sensitive, would become sick before the miners, who would then have a chance to escape or put on protective respirators. In some cases, the canaries were kept in cages with dedicated oxygen tanks so the birds could survive after their illness provided a warning.\9]) "Canary in the coal mine" is now used as an idiom for a person or thing that warns people of danger.\10])\11])
by cedelweiss
2 Comments
Danger? Where?
(Maybe Canari would have been harder if I didn’t have meganium or krookodile?)
Would’ve added to that WTF moment where Tarragon starts explaining that the hologram isn’t actually her.