Canaries, and birds in general, have evolved with a different respiratory system than humans. Their breathing system allows them to go from sea level to very high altitude with ease. It also means that they are far more vulnerable to slight increases in methane and carbon dioxide gas. Up until the late 20th century, coal miners took canaries down into the mines with them as a safety measure. Long before a human would be in danger from poisonous gas, the canary would stop singing and die, this was a signal to evacuate the mine immediately.
We are heading towards climate change at an alarming rate, and the people with the power to slow it down are unwilling to, because it does not fit within a 4 year political mandate, or within a CEO’s profit parameters. I really hope that the canaries pull through this okay!