I've always been inspired by the imagery of Ian Tyson's Wild Geese.

Wild geese flyin' by
Callin' on the downwind as they go
No answers they send
And springtime has too many miles to go.
Fly through the miles
Of country I've never seen before.
Why does the wind
Say you ain't comin' back any more?

Where I live this is a sight and sound that marks the time of year better than any calendar!