He said probably a half-dozen people contacted his department Monday with concerns about apparently disoriented birds flying into buildings and cars. 
 
 Not to worry, he said. Techar attributed the strange behavior to an early frost. Starch in the frozen berries is converted to sugar, and when they thaw again, yeast can enter the fruit and accelerate fermentation, yielding alcohol. 
 
 All this, before many birds have migrated out of the area, apparently has resulted in widespread avian inebriation, as the feathered flocks gorge on spiked fruit, mostly mountain ash berries. 
 
 Laura Erickson, a Duluth birding expert, said waxwings, robins and thrushes often are some of the most prone to become tipsy, as they commonly feed on such berries. 
 
 "Birds actually do get literally intoxicated when they eat berries that have started fermenting, and that does lead to drunken behavior," she said. 
 
 Techar said occasional reports of loopy birds are nothing new at this time of year, but weather conditions this fall have served up more than the typical share of alcohol-laden fruit. 
 
 "There is no need to call law enforcement about these birds, as they should sober up within a short period of time," he wrote. 
 
 "However, we would like you to call the Gilbert Police Department if you see the following," Techar added, obviously tongue in cheek: 
 
 • Heckle and Jeckle walking around being boisterous or playing practical jokes. 
 
 • Woodstock pushing Snoopy off the doghouse for no apparent reason. 
 
 • The Roadrunner jumping in and out of traffic on Main Street. 
 
 • Big Bird operating a motor vehicle in an unsafe manner. 
 
 • Angry Birds laughing and giggling uncontrollably and appearing to be happy. 
 
 • Tweety acting as if 10 feet tall and getting into confrontations with cats. 
 
 • Or any other birds after midnight with Taco Bell items. 
 
 As for the playful riff at the end of the news release, Techar said: "I wasn't going to do it, but we decided to show people that we've got a little bit of a sense of humor." 
 
 Who said law enforcement can't have a little fun once in a while? 
 
 Large numbers of birds and an increased risk of collisions are to be expected during this season, with or without fermenting berries, Erickson noted. Weather conditions also can temporarily halt bird movement, resulting in what's called migration fallout. 
 
 "It's par for the course at this time of year, but some years we have a much bigger, more noticeable fallout than other years, and this year's is pretty impressive," Erickson said. 
 
 She said small songbirds pausing in their travels often can be seen foraging for insects on the ground or along roadsides, where they typically can find warmer surface temperatures. 
 
 "It's been scary for people to drive when you have a whole collection of little warblers that are flitting right on the road, and people have been hitting a lot of them," Erickson said. 
 
 To reduce the risk of bird strikes, she recommends people adorn their windows with stickers, suncatchers, or strings. 
 
 "If people don't have that, birds smack into the windows, and the real tragedy with that is that half of the ones that fly off have bad enough wounds that they end up dying from head trauma," Erickson said. 
 
 Those birds that overindulge on fermented berries yet avoid windows may experience a different sort of head trauma. But fortunately it's nothing they can't sleep off. ||||| If birds that feed on winter berries in the Northern Hemisphere seem to be painting the town red, it could be because they're intoxicated. 
 
 Alcohol forms in berries as they ferment with the first frosts, and the birds that gorge on these winter fruits may get drunk more often than we think, scientists say. (See National Geographic's backyard bird identifier.) 
 
 "Most birds likely just get a bit tipsy, and very few people would be able to pick them out as intoxicated," said Meghan Larivee, laboratory coordinator at the government agency Environment Yukon in Canada. "However, every now and then, some birds just overdo it." 
 
 Such was the case with several Bohemian waxwings (Bombycilla garrulus) that flew into Whitehorse, Yukon, this fall, and ended up in "drunk tanks" after bingeing on fermented berries of the rowan tree. 
 
 The birds were admitted to the territory's Animal Health Unit, a wildlife facility equipped with modified hamster cages in readiness for the influx of berry-seeking migrants. 
 
 While there's no Breathalyzer for birds, it's pretty clear the waxwings were flying under the influence, according to Larivee. 
 
 "They cannot coordinate their flight movements properly or at all, and they are unable to walk in a coordinated way," she said in an email. 
 
 The birds, who come in with juice-stained beaks, are checked for illnesses that might otherwise explain their groggy condition. They generally recover after a few hours, she said. 
 
 Less fortunate are those intoxicated birds that die in collisions with buildings—two such fatalities were recorded in Whitehorse this fall. 
 
 An Alcohol Problem 
 
 While there are numerous anecdotal reports of such incidents in North America and Europe, there have been few studies to show that alcohol is indeed the cause. 
 
 One problem is that there's no routine test for diagnosing alcohol poisoning in animals, said Paul Duff, a veterinary scientist with the U.K.'s Animal and Plant Health Agency. The tests are "relatively expensive, and alcohol can disappear quickly. And toxicity leaves no characteristic lesions," he said. (Also see "Boozing Mammal Drinks 'Beer' Every Night, Study Finds.") 
 
 In 2011, Duff was called in as part of a police investigation into the suspicious deaths of 12 common blackbirds (Turdus merula) at an elementary school in the county of Cumbria in northern England. 
 
 Postmortem results, which included the detection of significant levels of alcohol in a liver sample, suggested the birds succumbed after eating fermenting rowan berries. 
 
 The same agency made a similar diagnosis for a group of redwings (Turdus iliacus) in 1999. The birds sustained fatal falls onto concrete from a berry-laden holly bush. 
 
 High Tolerance 
 
 The relatively large livers of waxwings and other species that rely on berries to get through winter are thought to help the birds handle alcohol. Young birds, however, may be more vulnerable. 
 
 Duff noted that the blackbirds he investigated in 2011 were all immature. "It is possible that adults learn to avoid toxic berries," he added. 
 
 A more obvious risk factor for drunk birds, certainly for those that flock to urban areas, are buildings and hard surfaces. 
 
 Bohemian waxwings that make their way south to Britain from Scandinavia in winter often make a beeline for ornamental berry trees in shopping center parking lots and residential areas. (Also see "'Drunk' Bats Fly Right—Discovery Surprises Scientists.") 
 
 In such an environment, being unable to fly straight may be lethal, said Ben Andrews, a wildlife advisor with the U.K.'s Royal Society for the Protection of Birds. 
 
 "We've had the odd report from people phoning us up and saying they've had a waxwing or waxwings dead under their window and things like that," Andrews said. 
 
 If you come across a live bird that appears drunk but uninjured, Andrews advises putting the animal in a cardboard box with some air holes for a few hours until they sober up and can be released. 
 
 Climate Change Effect? 
 
 But if outbreaks of insobriety aren't so unusual among berry-eating birds, might climate change make them even more frequent? 
 
 Though not an unusual fall phenomenon, 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, Larivee explained. 
 
 Larivee's recent waxwing patients were admitted to her Yukon animal unit following several frosts and thaws due to warmer temperatures. Average global surface temperature increased 1.5 degrees Fahrenheit (0.85 Celsius) from 1880 to 2012, according to the Intergovernmental Panel on Climate Change. 
 
 "We have to look at longer term trends when speaking about climate change, but we are seeing some changes," Larivee said. (Read more about the effects of global warming.)
– Apparently, the birds of Gilbert, Minn., can't handle their liquor. Case in point: The police department there has received several reports of birds that "appear to be 'under the influence' flying into windows, cars, and acting confused," according to a police department statement released this week. The culprit? An early frost. Or, more specifically, berries that froze, causing the starch they contain to convert to sugar, which in turn fermented when the berries thawed. "Birds actually do get literally intoxicated when they eat berries that have started fermenting," a bird expert tells the Duluth News Tribune. "And that does lead to drunken behavior." And it's pretty common, reports NPR, which dug up some other instances of boozey birds. In one case, the city of Whitehorse in the Yukon had to set up drunk tanks (modified hamster cages) for the "party fowl." As for Gilbert's winged drunkards, "There's no need to call law enforcement about these birds as they should sober up within a short period of time," per the police statement, which adds that there are some bird-related occurrences that should be called in. Among these are: "The Roadrunner jumping in and out of traffic on Main Street;" "Big Bird operating a motor vehicle in an unsafe manner;" and " Tweety acting as if 10 feet tall and getting into confrontations with cats."