Flocks of Bohemian waxwings are boozing it up on berries in Whitehorse, forcing Environment Yukon to improvise drunk-tanks out of hamster cages for crash-landed birds.

With snow already on the ground, fruit-eating birds like the Bohemian waxwing are filling up on all the food they can find before the subarctic deep freeze sets in. But several frosts and thaws this fall have led to berries fermenting on popular ornamental trees like mountain ash, says Meghan Larivee of Environment Yukon’s animal health unit.

“Birds that feed on these berries can become slightly intoxicated.”

Species like the waxwings actually have pretty good alcohol tolerance, owing to oversized livers, but nonetheless gobbling up too much fermented fruit can leave them in a stupor. The problem is compounded, Larivee says, when the birds store extra berries in their crops — an expandable pouch in the throat — where the berries ferment further before entering the digestive system, giving the birds a second hit of the joy juice.

Late last week, several Bohemian waxwings were brought to Environment Yukon after townspeople saw them feeding on mountain ash berries, then flying erratically and crashing into windows. The stunned birds were collected and placed in hamster cages to sober up.

“They needed to recover and have some alone time,” says Larivee.

She couldn’t confirm whether the birds in her care were actually drunk — “we’d have to do a blood-alcohol test on them” — but their beaks were stained red with mountain ash berry juice: a strong sign that they had been flying while imbibing.

Two of the rescued waxwings, Larivee says, have already died of trauma-related injuries.

Most bird species, she points out, have a hard enough time as it is navigating around reflective surfaces. Here in Toronto, thousands of sober birds die each year in collisions with windows.

Bohemian waxwings are indigenous to the higher latitudes of North America and Eurasia. The attractive birds — about the size of a budgie — sport grey plumage, black masks, small crests and waxlike splashes of red and yellow on their wingtips.

Local ornithologist Dave Mossop says the waxwings used to just stop over briefly in Whitehorse during their fall migration south to warmer destinations.

But, says the professor emeritus of biology at Yukon College, “they have been wintering in Whitehorse for several years now. As people grow more and more ornamental fruit trees, these kinds of birds, that can live on fruit, have been short-stopping their migration.”

According to a 2012 paper in the Journal of Ornithology, entire flocks of drunken cedar waxwings — a close cousin of the Bohemian waxwings — crashed to their deaths in Los Angeles in 2006 and 2007 after gorging on fermented berries. And there’s a similar phenomenon in Australia’s Northern Territory, where fermenting fruit leads to an annual drunken parrot season during which colourful lorikeets stagger about aimlessly and fall from trees.

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Scientists are still unsure of whether the birds are intentionally getting tipsy.

“It does happen, but it’s not common,” Mossop says. “All of us ornithologists are aware of literature that has birds being intoxicated from eating fermented fruit, but I’ve never heard of them actually seeking it out.”

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