Canary in the coalmine

Imagine being born with the ability to fly and then being chosen to be the one stuck in a dark cave with the sole responsibility of sending a warning signal when things were about to go badly. On top of that, we would be expected to constantly sing and have the pressure to only stop when an ominous situation was certain to prevail. The work and hard life of the poor little canary in the coalmine have gone underappreciated for not only the responsibility endured but also the greater metaphor of his toil.