A large number of apparently inebriated parrots are collapsing from trees and the sky in a northern Australian town, baffling veterinary doctors who are striving to look after them said.

The brightly coloured lorikeets are exhibiting typical symptoms of being tipsy by losing all harmonization and blacking out, and then trembling in cages as they recuperate from their "hangovers".

Lisa Hansen, a veterinary doctor at the Ark Animal Hospital in Palmerston, near Darwin said that they undeniably appear as if they are drunk.

She said, "They fall out of trees... and they're not so coordinated as they would normally be. They go to jump and they miss the next perch".

Hansen said that no one was certain that what was causing these signs, though chances are that they might be consuming a plant. Other theories comprise an outburst of a secret virus.

She said that the hospice that is seeking contributions was looking after around 30 birds at a time with eight coming every day after being picked up from lawns and pavements.

The birds are being fed sugared porridge and fresh fruit, the avian version of hangover food.

On Wednesday, Hansen told AFP, "It's probably the equivalent of ice-cream and cans of coke for the lorikeets".

She added that they sit on the floor of the cage and lean their heads on the side, or they coil up in the niche and cover themselves under the paper and forget about the rest of the world.