What is migratory restlessness shown by animals before long journeys?

• A. Constant frequency
• B. Zugunruhe
• C. Frequency modulation
• D. Echolocation

Answer: (B)

Migratory restlessness is a real behavioral drive where birds become unusually active and agitated as they anticipate a long journey, especially at night. This heightened activity, observed even in captivity during migration season, is known as Zugunruhe. The term, from German, captures the migratory impulse driven by internal rhythms linked to changing day length and hormonal signals, preparing the animal for departure and navigation. Scientists study Zugunruhe with setups like Emlen funnels to observe nocturnal activity and infer migratory direction. The other terms don’t fit this idea: constant frequency and frequency modulation are physics concepts about sound or signals, and echolocation is a sensory system used by some animals to navigate, not a pre-migration restlessness.