Visual guidance of flight in birds:

Inflight body awareness in budgerigars:


We have been investigating the birds ability to fly through narrow passages.

The results indicate that:
Budgerigars interrupt their normal wing-beat cycle when encountering passages that are narrower than their wingspan. The birds raise their wings or tuck them against their body, to prevent contact with the flanking panels. Our results suggest that the birds are capable of estimating the width of the gap with high precision: a mere 6% reduction in gap width causes a complete transition from normal flight to interrupted flight, vastly exceeding the performance of humans in similar experiments.

More information on this ongoing study is available here:
I. Schiffner, H. D. Vo, P. S. Bhagavatula, M. V. Srinivasan (2014)
Minding the gap: in-flight body awareness in birds.
Frontiers in Zoology 11(64).


Visual guidance of bird flight through narrow passages:


We have been examining the visual cues that budgerigars use to fly safely through narrow passages, by filming their flight trajectories when they fly along a tunnel whose walls are decorated with horizontal or vertical stripes.

The results indicate that:
When both walls carry vertical stripes (and therefore present strong image motion cues), the birds fly closedown the middle of the tunnel, i.e. equidistant between the two walls (center). When one wall carries vertical stripes and the other carries horizontal stripes (which present weak on no image motion cues), the birds fly very close to the wall that carries the horizontal stripes (left/right). These results indicate that budgerigars negotiate narrow passages by balancing the velocities of image motion (optic flow) that are experienced by the two eyes.

More information on this ongoing study is available here:
P. Bhagavatula, C. Claudianos, M. Ibbotson and M. Srinivasan (2011)
Optic flow cues guide flight in birds.
Current Biology 21, 1-6.


Edge detection in landing budgerigars:


We have been investigating the visual cues that determine where a bird will land.

The results indicate that:
Budgerigars use visual edges in the environment to target and guide landings. Edge detection in the context of landing appears to be a mediated by a colour-blind pathway, although the budgerigar possesses tetrachromatic colour vision.

More information on this ongoing study is available here:
P. Bhagavatula, C. Claudianos, M. Ibbotson and M. Srinivasan (2009)
Edge detection in landing budgerigars (Melopsittacus undulatus).
PLoS ONE 4(10): e7301.