The Mystery of Migratory Birds

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Across
  1. 3. The action, process, or result of combining or uniting.
  2. 4. A countless or extremely great number.
  3. 5. The ability to adjust to new conditions.
  4. 8. Relating to the approximate 24-hour cycle that is the physiological process of living beings.
  5. 9. Pertaining to the study of birds.
  6. 12. Make full use of and derive benefit from.
  7. 15. Relating to birds.
  8. 16. Strange or mysterious, especially in an unsettling way.
  9. 19. A complex combination of things or sequence of events.
  10. 20. Groups of stars forming recognizable patterns that are traditionally named after its apparent form or identified with a mythological figure.
Down
  1. 1. Characterized by several different modes of activity or occurrence.
  2. 2. Intermediate points on a route or line of travel.
  3. 6. Very complicated or detailed.
  4. 7. Temporary stays.
  5. 10. A confusing and difficult problem or question.
  6. 11. Relating to stars.
  7. 13. Put forward as fact or as a basis for argument.
  8. 14. The ability to detect a magnetic field to perceive direction, altitude, or location.
  9. 17. Relating to the magnetic field of the earth.
  10. 18. Uninterrupted connection or union.