birdcall vs song

birdcall and song both are nouns.

Word	Noun	Adjective	Verb	Adverb
birdcall	Yes	No	No	No
song	Yes	No	No	No

As nouns, birdcall and song are synonyms defined as:

Other synonyms of birdcall include birdsong, call.

birdcall (noun)	song (noun)
a device for imitating a birdcall	the act of singing
the characteristic sound produced by a bird	a short musical composition with words
	the characteristic sound produced by a bird
	a distinctive or characteristic sound
	a very small sum