The male’s breeding song is a jumble of clear notes mixed in with wheezes, trills, and stutters, lasting up to 10 seconds. Males incorporate snippets of the songs of many other species, including Ash-throated Flycatchers, Verdins, Curve-billed Thrashers, American Kestrels, scrub-jays, and many more.
When mingling in a flock, Lesser Goldfinches make a very common contact call that’s wheezy and descending, given one or two notes at a time. They also give a couple of chit notes in flight. Males give a descending tee-yer call to females during courtship.