Birds get 'drunk' on fermented berries
Wild young birds which may get 'drunk' on fermented berries suffer a fate worse than that of intoxicated humans, suggests a new veterinary study.
Researchers from the Animal Health and Veterinary Labs Agency (AHVLA) reveal how they were called to a primary school in Cumbria (England) last summer after the bodies of a dozen young blackbirds were found.
A few blackbirds were spotted on rowan trees, beneath which berries similar to those found in the dead birds' guts covered the ground. Many of these berries looked as if they had been partially eaten.
Post-mortem examinations of these birds revealed them to be in good physical condition. Tests ruled out lethal infections, such as avian flu. But berries were found in all the birds' guts, according to an AHVLA statement.
The authors can't explain why only one of the samples revealed the presence of ethanol, but suspect that all the dead birds had become intoxicated on fermented berries, and that some of the injuries they had sustained were the result of mid-air collisions in drunken state.
The berries on the ground were damaged, so would have been vulnerable to yeast infestation, which would have precipitated fermentation and subsequent alcohol production, they explain.
Rowan berries are not normally considered poisonous to wild birds, but the berries inside the birds smelled as if they were fermenting. Out of the three tissue samples sent for toxicological analysis, one revealed high levels of pure alcohol (ethanol).
A blackbird was discovered alive, but obviously "unwell". And two more dead birds were subsequently found. Foul play was suspected, especially as some of the birds had clearly been injured. The police were called.
Staff at the wildlife rescue centre, to which the live bird was sent, also reported that it had been unsteady on its feet and appeared "drunk".
The bird had to place its wings on the ground to steady itself, and had leant against the walls of its enclosure to keep upright, they said. After two days it fully recovered and was released back into wild.