The key physiological cue for migration is the modifications while in the day length. These modifications are associated with hormonal alterations during the birds. During the period of time just before migration, a lot of birds display better activity or Zugunruhe (German: migratory restlessness), 1st described by Johann Friedrich Naumann https://petsky-online-pet-shop-du98653.livebloggs.com/44294353/bird-shop-dubai-things-to-know-before-you-buy