Canary in a coal mine turned out to be for the birds ... "
George Orwell
Liliputins. What, the heck, is this?
http://stihi.ru/2021/11/24/7101
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A canary in a coal mine is a metaphor for an advanced warning of some danger.
The metaphor originates from the times when miners used to carry caged canaries while at work. If there was any methane or carbon monoxide in the mine, the canary would die before the levels of the gas reached those hazardous to humans.
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The phrase “for the birds” is an idiomatic expression that means something is worthless or not to be taken seriously. It’s often used to describe something that is considered trivial or of no value.