Birds that sip nectar or snack on fruit could be getting more than just sugar—they might also be getting a bit of alcohol.
A new study published in Ecological and Evolutionary Physiology reveals that some birds may regularly consume alcohol produced by the natural fermentation of sugary foods.
While it may sound funny to imagine a tipsy hummingbird, the research suggests there could be real biological effects.
The study, titled “The proof is in the plumage,” was led by scientists Cynthia Y. Wang-Claypool and colleagues from the University of California, Berkeley.
The team wanted to find out whether birds that feed on sugar-rich foods, like nectar and fruit, are more likely to be exposed to ethanol, the type of alcohol found in fermented foods and drinks.
They also wanted to see whether this alcohol exposure could be detected in a bird’s body.
To investigate, they tested for a chemical called ethyl glucuronide, or EtG. EtG is a substance that remains in the body after alcohol is broken down. It’s commonly used in humans as a reliable marker of alcohol consumption. However, this is the first time EtG has been studied in birds.
The researchers analyzed liver and feather samples from 17 different bird species. The samples came from salvaged birds that had already died and were donated to the Museum of Vertebrate Zoology in Berkeley. The method they used required taking feather samples from preserved specimens, which meant they were limited to birds already held in the museum’s collection.
Not surprisingly, the team found high levels of EtG in hummingbirds, which mainly feed on nectar. Since sugar in nectar can ferment and produce alcohol, these tiny birds may be consuming low levels of alcohol more often than we realize. Interestingly, the researchers also found EtG in birds with very different diets, such as those that eat seeds, insects, or even other animals. This means ethanol exposure in birds isn’t limited to sugar-loving species.
One especially intriguing finding was that hummingbirds living in urban areas had higher EtG levels, possibly because people often leave out sugar-water feeders. If these feeders are not cleaned regularly, the sugar water can ferment and produce alcohol, potentially turning a snack into a boozy drink for visiting birds.
The researchers caution that alcohol exposure in birds could affect their behavior and health. Even small amounts might impair flight or make birds more vulnerable to predators and accidents. Their study suggests that birds across many species might be exposed to alcohol more often than we think—and it’s time to take a closer look at what’s really in their diets.
Source: University of Chicago.
