Amazing stuff! Does it surprise anyone that a professor from the notorious UC Berkeley is researching this subject (it has a history of psychedelic drugs going back to the wild 1960s see e.g. here)? 😊
Next season, I see hummingbirds again near my home, I will keep this in mind! They are coming for the booze. 😊
The researcher has an apparent predilection for alcohol drinking animals see e.g. his earlier Drunken monkeys: what animals tell us about our thirst for booze. His specialty is integrative biology (integrative? How to integrate alcohol into the daily lives of animals?) 😊
"... nectar-filled flowers, which are an ideal gathering place for yeast — a type of fungus — and for bacteria that metabolize sugar and produce ethanol. ...
To University of California, Berkeley biologist Robert Dudley ... How much alcohol do hummingbirds consume in their daily quest for sustenance? Are they attracted to alcohol or repelled by it? Since alcohol is a natural byproduct of the sugary fruit and floral nectar that plants produce, is ethanol an inevitable part of the diet of hummingbirds and many other animals?
“Hummingbirds are eating 80% of their body mass a day in nectar ...The results of that study, published this week in the journal Royal Society Open Science, demonstrate that hummingbirds happily sip from sugar water with up to 1% alcohol by volume, finding it just as attractive as plain sugar water. ...
they sip only half as much as normal when the sugar water contains 2% alcohol. ..."
they sip only half as much as normal when the sugar water contains 2% alcohol. ..."
From the abstract:
"Both frugivores and nectarivores are potentially exposed to dietary ethanol produced by fermentative yeasts which metabolize sugars. Some nectarivorous mammals exhibit a preference for low-concentration ethanol solutions compared to controls of comparable caloric content, but behavioural responses to ethanol by nectar-feeding birds are unknown. We investigated dietary preference by Anna's Hummingbirds (Calypte anna) for ethanol-enhanced sucrose solutions. Via repeated binary-choice experiments, three adult male hummingbirds were exposed to sucrose solutions containing 0%, 1% or 2% ethanol; rates of volitional nectar consumption were measured over a 3 h interval. Hummingbirds did not discriminate between 0% and 1% ethanol solutions, but exhibited significantly reduced rates of consumption of a 2% ethanol solution. Opportunistic measurements of ethanol concentrations within hummingbird feeders registered values peaking at about 0.05%. Ethanol at low concentrations (i.e. up to 1%) is not aversive to Anna's Hummingbirds and may be characteristic of both natural and anthropogenic nectars upon which they feed. Given high daily amounts of nectar consumption by hummingbirds, chronic physiological exposure to ethanol can thus be substantial, although naturally occurring concentrations within floral nectar are unknown."
Robert Dudley, the integrative biologist, who watches birds drinking alcohol
Figure 1. Volumetric consumption differentials for binary choices between experimental nectar solutions over a 3 h interval, with concentration comparisons indicated beneath data points.
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