Bird lungs are remarkable.

Their respiratory system is designed in such a way that they can actually take in oxygen while both inhaling and exhaling. Because of this, birds are far more sensitive to changes like toxins and poisonous gases in the air.

Before the invention of the carbon monoxide detector, coal miners would take caged canaries with them down into the mines. If the birds started acting sickly––or outright passed out––it would be a warning to the coal miners to get the hell out of dodge.

It's said the coal miners had a special relationship with the canaries and treated them like pets, whistling to them while they worked.

Canaries are an interesting reminder that sometimes our greatest strengths can be our greatest weaknesses. A highly sensitive individuals is capable of marvelous creative feats but this same sensitivity makes them highly vulnerable to outside criticism.