You may have noticed that the singing of your friends goes a little off when they have had too much drink in the karaoke bar. Drinking too much alcohol can have an effect on the way people sing and it appears that this also applies with birds particularly with a species called zebra finches.

Many researchers are interested in studying the effects of alcohol on human speech but conducting such studies with humans can be difficult so a group of researchers turned to zebra finches, which like humans, learn to come up with complex sequences of sounds from those that surround them. The birds have long been used in studies that investigate how humans learn to communicate with language.

In a bid to learn the effects of alcohol on the learned song of the birds, Christopher Olson, from the Department of Behavioral Neuroscience at the Oregon Health & Science University, and colleagues placed a mixture of white grape juice with six percent alcohol in water bottles and put them in the cages of one group of zebra fiches. Another group of the birds also received the juice but without the ethanol content.

Olson noted that his team initially thought that the birds would not drink the concoction just like a number of other animals but the birds appeared willing to have the alcoholic drink.

"At first we were thinking that they wouldn't drink on their own because, you know, a lot of animals just won't touch the stuff," Olson said. "But they seem to tolerate it pretty well and be somewhat willing to consume it."

The birds became intoxicated even with blood alcohol level of only between .05 to .08 percent. The researchers observed that just like with humans, the voices of the birds were odd when they were drunk. The birds that had the spiked drinks, for instance, were not able to sing as loudly as when they are "sober," and they had problems keeping up with the normal structure of their song.

"The strongest effects of alcohol on song were on amplitude and entropy, detectable over whole motifs and at the individual syllable level," the researchers wrote. "Overall, alcohol has clear effects on zebra finch song."

Interestingly, the intoxicated birds did not appear to have suffered from the behavioral and health effects of drinking that humans face. Their ability to feed, perch, fly and maintain posture and the appearance of their feathers still appeared normal.