If you’re driving around Austria coming south on your way up to Vienna, you’re likely on a roadway called the A2. This 377.3 km (234.4 mi) stretch of highway is the longest in the country and typically moves pretty well. But if you were there in early October 2006, you may have been stuck in traffic for a while — a multiple-kilometer traffic jam gummed up the roads. There were three causes behind the delays, two of which are common: it was rainy, causing motorists to slow down, and there was a dense layer of fog, further giving drivers a reason to proceed with caution. But the third reason was something one rarely sees: there were about 40 dead birds in the way. It looked like they had just had just dive-bombed into the road — as if they had just fallen from the sky.
That’s because they had.
The birds weren’t sick — at least not in “bird flu” sense of the term, although that was everyone’s initial concern. And they didn’t fly into an invisible castle in the sky, although the actual explanation is only a bit less fantastical than that. Per Swedish news site The Local, the rain and fog played a role — the birds “didn’t know where they were going and lost their bearings over the motorway, crashing into cars and trucks.” Those conditions normally wouldn’t be enough to cause such confusion, but these birds had something else going on: they were drunk.
Autumn can be a tricky time to fly, it turns out. Birds eat berries but, in the fall, there’s a pretty good chance that those berries will end up with a relatively high alcohol content. If the temperature falls below freezing — not an uncommon occurrence overnight — the berries may freeze. They’ll thaw shortly after daybreak but by noon or so, the damage is done. As National Geographic explains, “freezing causes the berries to convert starches into sugars, while subsequent thawing makes it possible for yeast to get in and speed up the fermentation process.” Basically, the berries turn into little Jell-o shots but filled with berry bits instead of Jell-o. Eat enough of them and you’re going to end up pretty snookered.
And these birds on the Austrian roadway? They feasted on spiked berries. Discover Magazine quoted a spokesperson for Vienna’s veterinary authority as saying that “the birds’ livers showed so much damage from drinking that ‘they looked like they were chronic alcoholics.’” And like humans who are under the influence, going anywhere near a roadway was a bad idea. The drunk birds, it turned out, had flown way too low, smashing into the ground, car windows, and everything else with fatal results. (Well, fatal for the birds at least; there are no reports of injuries to people.)
Double bonus!: It turns out that drunk birds and drunk humans have another thing in common — we don’t sing well while intoxicated. In 2014, a team of researchers at Oregon Health and Science University got some zebra finches drunk and measured their chirping before and after. The results, per Smithsonian Magazine: “Blood-alcohol levels at about .05 to .08 percent—which in humans is enough to impair concentration and make you chatty—makes the birds ‘a bit less organized in their sound production,’ [lead researcher Christopher] Olson says.”
From the Archives: Mister Beer Belly: The man that brews his own beer — in his stomach.