Animals can use their circadian clocks to determine direction from the position of the sun. In a particular experiment conducted in Iceland, a bird, kept in a cage open to the sky, was trained to seek food on the western side. Its circadian rhythm was then phase-delayed by 6 hours and after phase shifting, the bird was returned to its open cage at 12.00 noon real time. It was observed to seek food in the:

a. north.

b. south.

c. east.

d. west.

I think that if its circadian rhythm was phase delayed by six hours, at noon, it will feel that it is still 6 a.m. So, the sun will be located in its "east" and it will try to seek food in the "west" but its"west" will be our south. So, answer should be south. Is my reasoning correct ?

  • $\begingroup$ I think it also matters when before the phase delay, the bird was fed. $\endgroup$ – Satwik Pasani Jan 17 '14 at 17:55

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