Built-in flight bias helps birds avoid colliding

Birds can fly in flocks and quickly navigate difficult environments without colliding with each other because individual birds show a predisposition to flying to the left- or right-hand side.

Scientists at the University of Queensland’s Queensland Brain Institute (QBI) and the Australian Research Council Centre of Excellence in Vision Science worked with budgerigars and found that individual birds display a bias for flying to the left or right.

This allows flocks to quickly navigate past obstacles by being able to split and not slow down due to crowding.

“We were looking at finding out how birds decide to navigate, because they’re very good at travelling through environments with narrow gaps, such as dense bush and forests, quickly and without collisions,” said Dr Partha Bhagavatula from QBI.

“By having a natural mechanism where populations of birds are predisposed to choosing different flight paths around obstacles, an entire flock could avoid situations where they block each other, slow down, lose time and expend more energy.”

Researchers flew the budgerigars down a tunnel where they were met by an obstacle and a choice of two paths to fly through. Sometimes the paths were of equal size and sometimes one would be bigger than the other.

“By giving birds the choice of flying left or right, through a pair of two adjacent openings, we were able to see that they displayed individual preferences,” Dr Bhagavatula said.

Some birds had no bias and would choose the wider gap every time, while others with a distinct bias preferred going to one side, even if it was significantly narrower than the alternative.

“This is very interesting and unexpected - because it’s generally expected for an animal species to have one dominant side that they prefer, such as humans being predominantly right-handed,” Dr Bhagavatula said.

Project leader Professor Mandyam Srinivasan says that more investigations need to be done on this by flying the birds in groups and seeing how individuals behave in a group dynamic, and whether they maintain those preferences when flying in a flock.

“What’s remarkable is that birds display a lateralisation bias in one task, such as route choice, but will have a bias for another task, such as what side they land on a perch, or what leg they favour to land on,” Professor Srinivasan said.

The findings could have implications for Professor Srinivasan’s work on robotic aircraft.

“The interactions between other aircraft are certainly very important, and when sending up autonomous aircraft without any human guidance it would certainly be worth investigating developing aircraft with individual biases like we see here,” he said.

The results of the study have been published in PLOS Computational Biology.