Scientists at UC Berkeley discovered that bees and hummingbirds drink small amounts of alcohol every day when they feed on flower nectar. The researchers tested nectar from 29 different plant species and found alcohol in 26 of them. The alcohol comes from yeast that naturally ferments the sugars in nectar.
Hummingbirds drink a lot of nectar each day, sometimes more than their own body weight. Scientists calculated that a typical hummingbird drinks about as much alcohol daily as a human having one alcoholic drink. However, the birds sip this alcohol slowly throughout the day and do not appear drunk.
The researchers believe hummingbirds burn through the alcohol so quickly that it does not build up in their blood. But the alcohol might still affect their behavior in subtle ways, similar to how caffeine and nicotine in flowers can influence animals.
Tests showed that hummingbirds will drink nectar with up to 1% alcohol, but they avoid higher amounts. Scientists also found chemical traces in bird feathers proving that hummingbirds process alcohol like mammals do. This suggests many animals evolved to tolerate alcohol in their diet.