The key physiological cue for migration would be the alterations inside the day size. These modifications are relevant to hormonal improvements in the birds. Inside the time period ahead of migration, quite a few birds Screen better action or Zugunruhe (German: migratory restlessness), initial explained by Johann Friedrich Naumann in https://bestdogfoodbrandsuae09753.shotblogs.com/the-fact-about-bird-that-no-one-is-suggesting-51717040