From Longman Dictionary of Contemporary Englishwarblewar‧ble /ˈwɔːbəl $ ˈwɔːr-/ verb 1 [intransitive]HBB to sing with a high continuous but quickly changing sound, the way a bird does2 [intransitive, transitive]APM to sing, especially not very well – used humorously Mills warbled a few notes. —warble noun [countable]→ See Verb table
Examples from the Corpus
warble• And what kind of tunes would be warbling along in the background?• Perhaps Clinton will inexplicably start warbling bird calls.• It leapt back into the air with an explosive flutter of wing and tail, warbling consternation, signalling alarm.• In a corner I could see the glass cubicle, where the steaming electronics hissed and warbled like something living.• My dad used to tease me to hell, warbling that song.• The trimphone extension warbled urgently from the wall.• I feel like singing, warbling, yodeling to Mr B and the Duke.Origin warble (1300-1400) Old North French werbler 