Homing pigeons can be taken from their lofts and transported hundreds of kilometers in covered cages to unfamiliar sites and yet, when released, be able to choose fairly accurate homeward bearings within a minute and fly home. ███
If the birds are using an internal magnetic compass to track displacement, then we would expect distorting magnetic fields to impair their ability to home but it does not reliably do so.
Mechanism ·Conscious navigation to track displacement
If the birds are tracking displacement by consciously tracking their movements (e.g., "I turned left and flew 3 minutes before diving low and then I turned right..."), then we would expect that anesthetizing them would impair their ability to home but it does not at all.
Criticism of Olfactory Hypothesis ·Pigeons cannot distinguish natural air from filtered air
If pigeons did use their sense of smell to create a map, presumably they would be able to tell natural, scent ladened air, from pure, filtered air. But they cannot.
Alternative Explanation ·for Papi's experimental results
Why did Papi's pigeons have trouble homing? It wasn't because they couldn't smell. It was because plugging their noses was a traumatic experience and interfered with their breathing.
Critique or debate passages contain multiple points of view on a particular subject. Sometimes the author takes sides and participates in the critique or debate, other times the author merely reports the debate.
Passages that focus on describing or evaluating potential explanations for a given phenomenon. Causal reasoning features prominently in these passages.
