english: When methane built up, or carbon dioxide built up, or oxygen was diminished, the birds would swoon before people would -- so it acted as an early warning system: Hey, get out of the mine. Things aren't going so well.
non_english: Keď sa zvýši množstvo metánu či oxidu uhličitého, alebo sa zníži množstvo kyslíka, vtáky omdlievajú skôr ako ľudia -- takže fungovali ako predčasný varovný systém: Hej, opustite bane. Niečo tu nie je v poriadku.