"My Grandmother used to say, 'They know it’s time to go.' And I of course, would ask, 'HOW do they know it’s time?' And always her same answer: 'Birds know these things.'
A lifetime later, I still watch--the gathering, the chattering, the bickering, the flapping, until the entire tree is aflutter. And then, as if on cue—HOMEWARD! So how DO they know? All I can tell you is this--birds know these things.
It’s common to most species, including our own--that urge to head south or north or across continents. A journey that eventually leads us home. It seems we know these things." – Ron Layport