A dozen young blackbirds were found dead at a school playground in Cumbria, England. An investigation indicated that the avian creatures suffered from alcohol poisoning due the birds eating fermented berries.
Most of the birds have trauma injuries sustained in flight caused by intoxication. A post-mortem analysis by the Animal Health and Veterinary Laboratories Agency disclosed that one of the winged creatures had a large amount of pure alcohol or ethanol in its liver.
The researchers said the blackbirds ate berries from a nearby rowan tree. They said that berries found on the ground were damaged and vulnerable to yeast infestation which caused fermentation, the chemical process of sugar breaking down into alcohol, and eventually it led to alcohol production.
One young blackbird which survived had symptoms of drunkenness. The researchers observed the creature pressing its wings into the ground to steady itself and trying to stay upright by leaning against the walks of an enclosure where it was kept for recovery. It was released after two weeks.
The scientists ruled out foul play or ailments such as bird flu.
Tim Harrison, development officer of the British Trust for Ornithology's Garden Birdwatch, told BBC that generally, birds with a lot of fruit in their diet are more efficient at metabolising alcohol and better adapted at eating fruit with higher alcohol concentrations. However, he said there are anecdotal reports of birds that act drunk, although these are very rare instances.
A similar incident was recorded in 199 when a group of redwings fed on holly berries that were fermented after a frost. Gizzard samples taken from the redwings yielded high levels of alcohol content.