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Alcohol can turn the quietest of people into exhibitionists, who, with the help of a karaoke machine can belt out hits such as 'I will survive' at the top of their lungs while slurring the words.

Now, scientists have discovered that alcohol has a similar effect on birds, whose songs become slurred and less well defined when they are under the influence.

The birds were given spiked juice and their songs carefully analysed for the tell-tale hallmarks of drunkenness.

The Birdie Song, or anything by Wings: Scientists gave zebra finches (stock image) juice spiked with alcohol and analysed the effect on their songs, to find that they were slurred and quieter than usual

Christopher Olson, of Oregon Health and Science University described an experiment where zebra finches were given juice with six per cent alcohol, on National Public Radio's All Things Considered show. 

They wanted to explore whether alcohol affects the songs of birds in the same way it does humans.

Zebra finches are commonly used to model human vocal learning and unravel how people communicate.

Dr Olsen told broadcaster Arun Rath: '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. But they seem to tolerate it pretty well and be somewhat willing to consume it.'

The unusual experiment set out to find out whether alcohol affects the songs of birds in the same way it does humans. A stock image of people in a karaoke bar is pictured

The birds had blood alcohol levels of between 0.05 and 0.08 per cent, which may not sound a lot, but produced the effects of drunkenness, because of the way that birds metabolise alcohol.

Birds could feasibly become 'drunk' in the wild, if they eat a lot of fermenting berries.

In the experiment, the scientists observed that the songs of the birds got quieter and became a little slurred, under the influence of the spiked juice.

Dr Olsen said: '[They became] 'a bit less organised in their sound production,' in the same way that humans slur their words and songs in a distinctive way.

In the future, he plans on exploring whether alcohol not only alters the way birds sing, but if it alters the way they learn new tunes too.

...HERMIT THRUSHES SING LIKE HUMANS IN 'HARMONIC SERIES' 

The Hermit thrush may well be the Beyoncé of the bird world thanks to its tuneful melodies, a study revealed last month.

Scientists have discovered that the North American songbird sings in 'harmonic series', a pattern of pleasing-sounding notes commonly used in popular human music.

By studying how birds sing, experts hope to learn how much of human musical heritage is shaped by biology, compared to culture.

A harmonic series stems from a base note and is followed by notes that increase in pitch, based on multiples of the original note.

Scientists have discovered that the hermit thrush (stock image) sings in 'harmonic series', a pattern of pleasing-sounding notes commonly used in popular human music

Scientists found that around 70 per cent of the bird's songs followed this pattern, Smithsonian reported.

Male hermit thrushes sing between six and 10 types of song, which tend to be high-pitched and fast, beginning with a long whistle, the study revealed.

Emily Doolittle, a composer at Cornish College of the Arts in Seattle and Tecumseh Fitch, a biologist at the University of Vienna, analysed 144 different song types from 14 male hermit thrushes.

'Listening to the songs full speed, they are very attractive, but we didn't have any inkling that we would hear the harmonic series in them,' Dr Doolittle said.

But after they slowed them down, the harmonic series patterns became clear and statisticians analysed the bird's choices of pitch in the song.

Around 70 per cent of the songs analysed followed harmonic intervals, compared to just five per cent which seemed to include random notes.

Dr Doolittle emphasised that the birds don't deliberately compose their songs using scales, but noted that other birds also like intervals used in human music.

For example, previous studies have shown that musical wrens use them and domestic chickens favour consonant notes – a combination of notes that sound pleasant when played at the same time.