Authors trained parakeets to go through a gap and then changed the widths to see the what happened. If the gap was narrower than their wingspan the birds would adjust their position when going though the gap.

Schiffner et al. Frontiers in Zoology 2014 11:64 doi:10.1186/s12983-014-0064-y

Minding the gap: in-flight body awareness in birds

Introduction

When birds fly in cluttered environments, they must tailor their flight to the gaps that they traverse. We trained budgerigars, Melopsittacus undulatus, to fly through a vertically oriented gap of variable width, to investigate their ability to perform evasive manoeuvres during passage.

Results

When the gap was wider than their wingspan, the birds passed through it without interrupting their flight. When traversing narrower gaps, however, the birds interrupted their normal flight by raising their wings or tucking them against the body, to prevent contact with the flanking panels. Our results suggest that the birds are…