These zebra finches are part of an art installation in London's Barbican Center that's become a musical sensation, says Assistant Curator Ariella Yedgar. "It's musical, there's so much to look at. There's live birds in a gallery which is really exceptional, so we thought it would appeal to lots of people but it's exceeded our expectations in that way."

Only 25 people at a time are allowed in. Some wait quite a while before getting into the small exhibition space.

The entrance is dark, with projections of electric guitars on the walls. The space then opens up and birds flutter between man-made islands, tapping on amplified Les Paul guitars and upturned cymbals, producing music of a sort. Yedgar says there are rules.

"Don't feed the birds, because they're on a very strict and healthy diet. In general be respectful, don't make any sudden sounds. They really love being around people but we don't want them to feel uncomfortable."

The birds seem comfortable around people. They peck at shoes and cluster around a camera tripod.

The 40 finches here are regularly checked by specialists to make sure they're healthy. They've been here a couple of months but even in this controlled environment, they know it's springtime.

The finches are lining their nesting boxes, and some are looking for other places to nest - on guitars and the exit sign.

Visitors seem to love them. "I'm delighted not only because of what I'm seeing, but also because the grandchildren are enjoying it. And that's the whole point really to show them something new."

The exhibit is the brainchild of French composer and artist Céleste Boursier-Mougenot who wanted to explore the rhythms of daily life.

Musician Bobby Gillespie, who leads the band Primal Scream, heard about it from colleagues. "The birds are probably better musicians than most musicians."

Gillespie thought this would inspire his children. "It can encourage them to think that, you know, anybody can make music, you know, even a little bird jumping on an electric guitar, you know."

In a world where twitter and tweets are a new way to communicate, these birds are making a different kind of music.