Scientists just discovered bees and hummingbirds are drinking alcohol
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Scientists just discovered bees and hummingbirds are drinking alcohol
It turns out bees and hummingbirds aren’t just sipping nectar—they’re having tiny, constant “cocktails” all day.
Date:
March 25, 2026
Source:
University of California - Berkeley
Summary:
Flower nectar often contains small amounts of alcohol, meaning pollinators like hummingbirds are drinking it all day long. Despite consuming human-equivalent amounts, they show no signs of intoxication—suggesting a surprising evolutionary tolerance.
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Many flowers naturally produce tiny amounts of alcohol in their nectar, and pollinators are consuming it constantly. Credit: Shutterstock
As bees and hummingbirds move from one flower to another, feeding on nectar while helping plants reproduce, they are also consuming something unexpected: small amounts of alcohol.
In the first large survey of alcohol in floral nectar, biologists at the University of California, Berkeley detected ethanol in at least one sample from 26 of the 29 plant species they examined. Most nectar samples contained only trace amounts, likely produced by yeast fermenting sugars. However, one sample reached 0.056% ethanol by weight, which is about 1/10 proof.
How Much Alcohol Do Pollinators Consume
Although these levels sound tiny, nectar is a primary energy source for many species. Hummingbirds, for example, drink between 50% and 150% of their body weight in nectar each day. Based on these feeding habits, the researchers estimate that an Anna's hummingbird (Calypte anna), commonly found along the Pacific coast, consumes roughly 0.2 grams of ethanol per kilogram of body weight daily. That is comparable to a human having about one alcoholic drink.
Despite this regular intake, bees and birds consume the alcohol gradually throughout the day and do not show clear signs of intoxication. Earlier work by the same team found that hummingbirds will drink sugar water containing up to 1% alcohol, but they begin to avoid it when concentrations rise above that level.
Possible Effects Beyond Intoxication
Even so, nectar contains other compounds, such as nicotine and caffeine, that are known to influence animal behavior. Ethanol could have similar subtle effects.
"Hummingbirds are like little furnaces. They burn through everything really quick, so you don't expect anything to accumulate in their bloodstream," said doctoral student Aleksey Maro, who worked on the nectar analysis with postdoctoral fellow Ammon Corl. "But we don't know what kind of signaling or appetitive properties the alcohol has. There are other things that the ethanol could be doing aside from creating a buzz, like with humans."
"There may be other kinds of effects specific to the foraging biology of the species in question that could be beneficial," added Robert Dudley, UC Berkeley professor of integrative biology. "They're burning it so fast, I'm guessing that they probably aren't suffering inebriating effects. But it may also have other consequences for their behavior."
Maro, Corl and Dudley reported their findings March 25 in Royal Society Open Science, along with Berkeley colleagues Rauri Bowie and Jimmy McGuire, both professors of integrative biology and curators at the campus's Museum of Vertebrate Zoology.
Experiments Reveal Alcohol Tolerance
Earlier experiments conducted at a feeder outside Dudley's office showed that Anna's hummingbirds are largely indifferent to low alcohol concentrations in sugar water (below 1% by volume). However, when the concentration reaches 2%, they visit the feeder about half as often.
"Somehow they are metering their intake, so maybe zero to 1% is a more likely concentration that they would find in the wild than anything higher," he said.
Another study led by former graduate student Cynthia Wang-Claypool found that feathers, including those of Anna's hummingbirds, contain ethyl glucuronide, a byproduct of ethanol metabolism. This indicates that these birds not only ingest alcohol but process it in a way similar to mammals. Together, these findings suggest that birds and other animals, including human ancestors, may have evolved a tolerance for and sometimes even a preference for alcohol.
"The laboratory experiment was showing that yes, they will drink ethanol in their nectar, though they have some aversion to it if it gets too high," Corl said. "The feathers are saying that, yes, they will metabolize it. And then this study is saying that ethanol is actually pretty widespread in the nectar they consume."
Comparing Alcohol Intake Across Species
After measuring ethanol levels using an enzymatic assay, the team estimated daily alcohol intake for several nectar-feeding species based on their caloric needs. Because detailed feeding data are limited, they focused on two hummingbird species, including the Anna's hummingbird, and three species of sunbirds, which in South Afric