An Australian study of bird flights could lead to improvements in pilotless aircraft, particularly for navigation through environments such as canyons, gorges or under bridges.

The research by scientists from the University of Queensland and the Australian National University found that birds avoid crashing by sensing the speed of objects that fly along their path.

"If birds fly closer to objects on one side they'll see these objects passing faster compared to the speed of objects on the other side, which appear slower from their perspective. ... This imbalance prompts the bird to veer away to even out the speed of image flow in both eyes," co-author Professor Mandyam Srinivasan from the Queensland Brain Institute told TruthDive.

To prove their theory, the researchers trained budgrigars to fly though narrow passages which were lined with horizontal or vertical stripes. The birds flew fastest in passageways with horizontal stripes.

Srinivasan explained that from the bird's point of view, stripes that are parallel to their flight direction do not present a strong image flow, which is the rate at which images pass bird's eye.

When the birds flew through vertical and horizontal stripes, most of them flew closer to the horizontal stripes because the vertical stripes projected a stronger image flow to their corresponding eye, making them veer away to restore the balance between the flows experienced by their two eyes, said co-author Pertha Bhagavatula of the Vision Centre and the National Vision Research Institute.

That experiment had similar findings to earlier tests made by the researchers using bees and other insects with compound eyes.

"These findings can contribute to the technology of guiding unmanned aerial vehicles where aircraft have to fly through obstacles in cluttered environments," the Times of Oman quoted Srinavasan.

The study was published in the Current Biology journal.