Hummingbirds, the smallest species of birds in the world, are tiny, cute and…alcohol drinkers? Yes, according to Robert Dudley, a biologist from University of California, Berkeley. These small birds drink their alcohol from flowers and feeders (an outdoor device that supplies food for wild birds).
The nectar that hummingbirds sip has alcohol content because naturally occurring yeasts, a type of fungus, metabolize sugar and produce ethanol (also known as ethyl alcohol). Ethanol is the alcohol in our drinks. It is made when yeast ferments the sugars in grains, fruits and vegetables. The same natural process happens to nectar.
"Hummingbirds are eating 80% of their body mass a day in nectar," said Dudley. "Most of it is water and the remainder sugar. But even if there are very low concentrations of ethanol, that volumetric consumption would yield a high dosage of ethanol, if it were out there” he added.
But why don’t hummingbirds fall drunk on the ground or fly zigzag (and lose their license for flying under the influence of alcohol, ha ha)? It’s because they burn the alcohol and metabolize it so quickly. Likewise with the sugars. They don’t get drunk.
It’s not just hummingbirds that are guilty of drunk flying. Bees and bats too. Like hummingbirds, bees get drunk from nectar. Tropical bats of Central and South America ingest ethanol from fermenting fruits and nectar. But, like the hummingbirds, bats don’t seem to be affected. They can fly and use their built-in "sonar" just as well while drunk as while sober, even with blood-alcohol contents that would exceed legal limits for people.
There are other animals, not just birds and bats, that take in alcohol. A study, published in 2015, found a relatively high alcohol concentration of up to 3.8% in the nectar eaten by the slow loris (Nycticebus coucang), a type of primate. Both slow lorises and aye-ayes (Daubentonia madagascariensis), another primate, preferred nectar with higher alcohol content.
An earlier study in 2008, published in the Proceedings of the National Academy of Sciences, found that the pentailed tree shrew (Ptilocercus lowii), a tiny animal living in the Malaysian rainforest, had a habit of revisiting the bertam palm tree every night to suckle on its naturally fermented nectar.
Researchers found that the nectar had 3.8 percent alcohol content, about the same as a weak beer. The shrew was seen returning to the tree up to three times in a night to drink. The amount of nectar they consume is equivalent to 10–12 glasses of wine for humans, adjusted to body weight. The shrews weren't seen exhibiting signs of drunkenness. Their ability to ingest high amounts of alcohol is hypothesized to have been an evolutionary adaptation.
While some species can tolerate alcohol in their body, others cannot. In 2011, a “drunk” moose was found stuck in a tree in Sweden. Apparently, the animal became entangled in the limbs of a small tree after eating fermented apples, which can be found in abundance in yards and fields in the fall. The drunken moose was caught with three legs off the ground and was eventually freed.