Birds and Bees Enjoy a Buzz: Pollinators Consume Alcohol in Nectar
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. A recent study from the University of California, Berkeley, has revealed that flower nectar often contains ethanol, and pollinators are regularly exposed to it.
Widespread Alcohol in Floral Nectar
In the first large survey of alcohol in floral nectar, biologists at UC 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. The findings were published in Royal Society Open Science on March 25, 2026.
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, 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. This is comparable to a human having about one alcoholic drink, according to the study.
Tolerance and Metabolism of Ethanol
Despite this regular intake, bees and birds consume the alcohol gradually throughout the day and do not display clear signs of intoxication. Earlier research by the same team showed that hummingbirds will drink sugar water containing up to 1% alcohol, but they commence to avoid it when concentrations rise above that level. Previous studies have also found that hummingbird feathers contain ethyl glucuronide, a byproduct of ethanol metabolism, indicating that these birds process alcohol similarly to mammals.
Potential 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. “But we don’t grasp 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.”
Robert Dudley, UC Berkeley professor of integrative biology, added, “There may be other kinds of effects specific to the foraging biology of the species in question that could be beneficial. 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.”
Comparing Alcohol Intake Across Species
The researchers estimated daily alcohol intake for several nectar-feeding species, including hummingbirds and sunbirds (which fill a similar ecological role in Africa). They also compared these values with other animals, including the European honeybee, the pen-tailed tree shrew, fruit-eating chimpanzees, and humans consuming one standard drink per day. The tree shrew had the highest intake at 1.4 g/kg/day, while the honeybee had the lowest at 0.05 g/kg/day. Nectar-feeding birds consumed about 0.19 to 0.27 g/kg/day when feeding on native flowers.
Interestingly, the feeder experiments suggest that Anna’s hummingbirds may ingest even more alcohol from fermented sugar water in feeders (0.30 g/kg/day) than from natural nectar.
Evolutionary Implications
This research is part of a broader five-year National Science Foundation project aimed at collecting genetic data from hummingbirds and sunbirds to understand how they adapt to different environments and food sources, including frequently fermented nectar. The findings suggest that a tolerance for, and even a preference for, alcohol may have evolved in animals over time. “These studies suggest that there may be a broad range of physiological adaptations across the animal kingdom to the ubiquity of dietary ethanol, and that the responses we see in humans may not be representative of all primates or of all animals generally,” Dudley said. “Maybe there are other physiological detoxification pathways or other kinds of nutritional effects of ethanol for animals that are consuming it every day of their lives. That’s the interesting thing — this is chronic through the course of the day, but that’s a lifetime exposure post-weaning. It just means that the comparative biology of ethanol ingestion deserves further study.”
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