A few years ago I caught a few minutes of an absolutely fascinating documentary explaining how many animals become (and deal with being) intoxicated. Lemurs seeking out millipedes which emit noxious substances, bees becoming drunk on a certain kind of sap, and other examples were covered, although I have never been able to track the show down to watch the rest of it. I was reminded of this show as some scientists are now wondering if certain types of sugar may help bats sober-up quicker.
As some fruits like dates and figs ripen, ethanol (drinking alcohol) accumulates in the fruit, but even a very small amount could be lethal to bats. Even if a lethal amount is not ingested, a drunk bat is a bat that likely will not be able to dodge predators or obstacles, so it is in their best interests to reduce the effects of ethanol in their systems. Of course, it is important to remember that in this discussion we’re primarily speaking of fruit bats, like the Egyptian Fruit Bat, and not of the little brown bats that might be flittering about your house at night. Anyway, upon testing researchers found that bats that ingested a small amount of ethanol with fructose (glucose and sucrose were also tested) showed a bigger drop in alcohol levels when given a breath test (which must have been an interesting sight). Indeed, bats also seemed to prefer more fructose-laden food, although overall bats preferred sucrose to anything else.
Overall, the behavior reminds me a bit of geophagy in tapirs and babirusas, where upon ingesting plants full of toxins the mammals eat certain clays that have a medicinal effect. Do the animals understand the cause-effect relationship of eating a certain food when sick? Possibly, but I don’t know enough about what goes on in a tapir’s head to really say either way. As for the bats, since they appear to prefer sucrose regardless of the alcohol content in their food but increasingly prefer fructose as they consume ethanol, perhaps it’s merely a matter of taste; some sugars are more appealing than others and perhaps tastes change as bats take in more ethanol from their food.
Intoxication in animals is a very interesting topic, and I’m surprised it hasn’t been well-studied. I remember clearly from the documentary I cited above that if a drunk bee came back to the have, it would be kicked out by guards at the entrance (the bee equivalent of a bouncer I suppose). If the same drunk bee continued to come back, the guards would bite off a few appendages, and I had never heard of such behavior in insects before. While further study would be needed, perhaps bees are like us in that they like to get “buzzed” every now and then.