Dead birds in NE Portland may be linked to fermented berries
Dozens of birds have been found dead in northeast Portland, and experts believe berries may be to blame.
The Audubon Society of Portland said they have been receiving reports of dead birds in the area of Northeast Russell Street and Rodney Avenue.
Audubon Society veterinarians suspect the birds are eating fermented berries, which can lead to poisoning.
U.S. Fish and Wildlife workers are performing necropsies to determine the official cause of death.
A Fish and Wildlife spokesperson said that will likely take three to four weeks. The spokesperson could not confirm fermented berries were involved in the recent bird deaths yet, but said a similar situation happened back in 2008.
Due to cold weather that winter, red robins couldn't dig into the ground for worms, so they ate holly berries and died. The deaths were attributed to alcohol poisoning from fermented berries.
Hmm I'm a bit skeptical about the explanation
for the mass die off that's been provisionally proffered here. American robins being thrushes are well adapted to eating all sorts of berries for months during the winter. Still really a mystery at the moment I think, until the data from the investigation is released to the public.
Edit - Fwiw, just found this report about the results from a similar incident last year in UK which to my reading was still far from conclusive regarding intoxication as a cause of death.
Dead birds were intoxicated, an investigation finds
Young blackbirds found dead at a primary school in Cumbria suffered from alcohol poisoning, according to an investigation.
Animal health specialists were called to examine a dozen birds found in the playground, many with trauma injuries.
Post-mortem analysis revealed that one of the birds had a large amount of pure alcohol in its liver.
Scientists suggest the birds sustained their injuries in flight because they were intoxicated by fermented berries.
Staff from the Animal Health and Veterinary Laboratories Agency (AHVLA) published their results in the Veterinary Record.
A local wildlife sanctuary cared for a further bird found in the area, which they described as unsteady on its feet, using its wings to support itself and leaning on the walls of its enclosure.
The bird made a full recovery and was released after two weeks of care.
When AHVLA researchers analysed the dead blackbirds they found all the birds had eaten berries from a nearby rowan tree.
Tim Harrison, development officer of the British Trust for Ornithology's (BTO) Garden BirdWatch explained: "Generally speaking, birds that have a lot of fruit in their diet are more efficient at metabolising alcohol and are better adapted at eating fruit that has higher alcohol concentrations."
He continued: "There are anecdotal reports of birds acting 'drunk' but these tend to be very rare".
But damaged berries were also recorded on the ground where the birds were discovered.
Scientists explained that the berries on the ground were damaged and would have been vulnerable to yeast infestation. This would have precipitated fermentation and subsequent alcohol production.
According to Paul Duff and colleagues at the AHVLA, who carried out the post-mortem analysis on the dead blackbirds, the berries found in the birds' guts smelled of fermentation - the chemical process of sugars breaking down into alcohol.
Tissue samples sent for analysis partially confirmed the scientists' suspicions when one revealed high concentrations of ethanol, pure alcohol, in the liver of an affected bird.
However, alcohol was not identified in the toxicology tests of two other samples.
A similar diagnosis was made in 1999 for a group of redwings, which had been feeding on holly berries that were fermenting following a frost.