Birdsong rhymes with:
hissong, hussong, hysong, plainsong, budlong, chamlong, daylong, furlong, headlong, headstrong, hissong, hourlong, hussong, hysong, monthlong, plainsong, scuppernong, ssangyong, weeklong
Birdsong sounds like:
birdwatching, boardgames, brautigams, breathtaking, bridging, brodzinski