How exactly do birds get drunk eating fruit? Fermentation should be anaerobic
The insides of fruits are relatively anaerobic environments. Natural fermentation, as in berries that get birds intoxicated, is primarily from yeast, and it seems most likely that humans recognized this process before intentionally encouraging fermentation of anything. Natural fermentation reaching high ethanol concentrations occurs especially when berries high in sugar are frozen and then thawed.



Dudley, R. (2004). Ethanol, fruit ripening, and the historical origins of human alcoholism in primate frugivory. Integrative and comparative biology, 44(4), 315-323.

Fitzgerald, S. D., Sullivan, J. M., &amp; Everson, R. J. (1990). Suspected ethanol toxicosis in two wild cedar waxwings. Avian Diseases, 488-490.