The song's structure is interesting because the six-line chorus is longer than both four-line verses. It starts with Young reassuring his lover that there will be "another one who'll hover over you beneath the sun." The chorus then paints an image of Young flying away from his "little one," ending with the sweetly spoken yet harsh assurance that "it's over."
It's a beautiful song (though Jimmy McDonough among others feel it was overworked in the studio) that's even more interesting looking at Young's life and career as a whole. He's always shown a penchant for abandoning people, from lovers to friends to bands. It's a notorious aspect of his personality, and one he himself has lamented on many occasion, both in interview and in song, for instance, "Running Dry (Requiem For The Rockets)
"Birds" can be viewed as another song of Young chronicling his own tendency to burn bridges and leave people behind as he chases his muse. Or, it can be enjoyed simply as a tale of the universal complexities of romantic love.