Christopher Leahy, in his book The Birdwatcher’s Companion, wrote: “In North America, [migration] involves about 80 percent of the approximately 645 species of breeding birds. ”
Christopher Leahy kirjutas oma raamatus ” The Birdwatcher’s Companion ”: ” Umbes 645 - st Põhja - Ameerikas pesitsevast linnuliigist moodustavad 80 protsenti [rändlinnud]. ”