Researchers from the University of California, Berkeley, aimed to find out how often hummingbirds consume alcohol.
The fact is that both flower nectar and sweet water in specialized feeders undergo fermentation due to microorganisms. If we consider a standard hummingbird feeder with a twenty percent sucrose solution, it can accumulate 0.05% ethanol over two weeks. At first glance, this is a small amount; however, it is important to note that hummingbirds consume liquids equivalent to 80% of their body weight daily. Thus, the total amount of alcohol they absorb, while not significant, cannot be considered negligible.
Moreover, hummingbirds are not averse to stronger drinks: during the experiment, they were offered feeders with sugar water without ethanol and with 1% ethanol, and the hummingbirds drank both the alcohol-free water and the one with alcohol with equal pleasure. However, when the alcohol level was increased to 2%, the birds approached that feeder less frequently, although they still continued to drink. Ultimately, the amount of alcohol consumed from the two percent feeder corresponded to what they obtained from the one percent feeder. It can be asserted that hummingbirds do not mind having a drink but know their limits. Likely, the alcohol they consume does not have time to affect their behavior, as it is quickly processed by their metabolism.
As for nectar, the ethanol content in flowers has not yet been systematically measured. (However, for some plants, such data is available: for example, it is known that some palms can have up to 3.8% alcohol in their nectar.) Therefore, the next step for researchers will be to assess the alcohol level in the flowers that hummingbirds feed on, as well as to conduct similar experiments with honeycreepers and nectarivores—two other families of birds that also feed on nectar. A few years ago, we reported that drunken birds get confused in their songs, but that was about finches that were in a laboratory setting and had no choice but to drink or not drink. In the case of hummingbirds, it has been demonstrated for the first time that some birds do not have a strong aversion to alcohol and are willing to have a little drink without any coercion.
