A hummingbird instinctively knows when to leave its breeding grounds. Fewer hours of daylight trigger hormonal changes that cause the urge to fuel up and fly south even though nectar-rich flowers are still in bloom and sugar-water feeders are full.
"We"ve had a wonderful summer of hummingbird sightings. They've been busy slurping up nectar. We will miss them all when they leave in a few weeks."
Anne Brain, Needham, Massachusetts, 08/21/14
Amy Evoniuk
