New York, June 1 (IANS): Responding a yawn with a yawn is not restricted to humans and a few other mammals alone as researchers have now found that it also happens with members of a bird species of Australian origin.

Contagious yawning occurs between budgerigars (Melopsittacus undulatus), also known as parakeets that are often kept in cages as pets.

"To date, this is the first experimental evidence of contagious yawning in a non-mammalian species," said study leader Andrew Gallup of the State University of New York in the US.

Contagious yawning was previously thought only to occur between members of a few mammals -- humans, domestic dogs, chimpanzees and a type of rodent aptly called the high-yawning Sprague-Dawley rat.

Gallup's team conducted two experiments. In the first, 16 birds were paired in adjacent cages with and without barriers blocking their view.

In the second experiment, the same birds were shown separate video clips of a budgie yawning and not yawning.

Yawning was found to occur three times as often within a five-minute window when the birds could see one another than when their view was blocked from the other bird.

When they were viewing video clips of another budgie yawning, yawns occurred twice as often. This response was not the result of stress or anxiety.

The researchers believe that contagious yawning is more than just an involuntary action, but is rather a primitive form of showing empathy.

The study was published in Springer's journal Animal Cognition.