Several people are believed to have broken into the Launceston zoo overnight on Thursday, cut the locks on enclosures and slaughtered about a dozen birds.

"They've gone on a rampage," the co-owner of the private zoo, Rochelle Penney, said. "They have gone in there with the purpose of harming the animals."

Several birds were found with their heads removed.

"It’s baffled us," said Ms Penney, whose family opened the zoo nine years ago. "We're all in shock really."

About 1000 birds were released from their cages but many have been recaptured. The missing animals included quolls and endangered swift parrots.

''People don't understand, a lot of those guys won't survive in the wild,'' Ms Penney said.

Other unlocked enclosures were reported to house wallabies and monkeys.

Two chainsaws were also stolen.