Overview
- UC Berkeley biologists, publishing Wednesday in Royal Society Open Science, detected ethanol in nectar from 26 of 29 plant species, with a top sample of 0.056% by weight.
- Because hummingbirds drink roughly 50% to 150% of their body weight in nectar each day, the team estimates an Anna’s hummingbird takes in about 0.2 grams of ethanol per kilogram daily, similar to a human having one drink.
- Across species, estimated daily intake ranged widely, with pen-tailed tree shrews highest at 1.4 g/kg/day, honeybees lowest at 0.05 g/kg/day, and nectar-feeding birds near 0.19 to 0.27 g/kg/day on native flowers.
- Tests indicate fermented sugar water in backyard feeders can raise exposure for Anna’s hummingbirds to about 0.30 g/kg/day, exceeding intake from natural nectar.
- Earlier studies show hummingbirds handle ethanol, with steady visits to nectar at up to 1% alcohol and feather markers of ethanol metabolism indicating they process what they ingest.