The black redstart is a bird species that migrates a relativ…
The black redstart is a bird species that migrates a relatively short distance from Germany to the Mediterranean region of Europe, whereas the common redstart travels as much as 5000 km from Germany to central Africa. The scale in the figure below shows the duration of migratory restlessness in captive black redstarts, common redstarts, and hybrids between the two species all of which had been hand-raised under identical conditions. (a) Why do black redstarts exhibit migratory restlessness at night for fewer days than common redstarts? (b) What does the behavior of the hybrids tell us about the genetic differences hypotheses for the differences in duration of migratory restlessness in the two parental species?
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