1610s, agent noun from warble (v.). Applied to Old World songbirds by 1773 and to North American birds that look like them but sing little by 1783.
Entries linking to warbler
warble v.
late 14c., from Old North French werbler "to sing with trills and quavers" (Old French guerbloiier), from Frankish *werbilon (cognate with Old High German wirbil "whirlwind," German Wirbel "whirl, whirlpool, tuning peg, vertebra," Middle Dutch wervelen "to turn, whirl"); see whirl (v.). Related: Warbled; warbling. The noun is recorded from late 14c.