not sure if it has ever been mentioned… not sure if i got it right… not sure if my english is good enough to share my thougt…
miners used to take birds with them underground. they did that because birds run out of oxygen much faster than humans. the birds would get weird and sing, just before dying, because they lack of oxygen. it was a deathproof sign for the miners if the bird went crazy, they knew they had to leave the cave asap.
when does a bird sing?
q might ask this question over and over again to tell us that these people are close to asphyxia.