Verb (used without object) : The canary warbled most of the day.    From Dictionary.com. 

That is called warbling, or trilling, or trolling, or something.    From Wordnik.com.  [Peck's Uncle Ike and The Red Headed Boy 1899] Reference

Eduardo Miranda shuts the door of his study, leaving two "warbling" robots to their own devices.    From Wordnik.com.  [Reason Magazine - Hit & Run] Reference

Comments: I can't remember anything about this one other than "warbling" which I've written in my notes next to it.    From Wordnik.com.  [Everything2 New Writeups] Reference

That through the warbling throats of Syren nymphs.    From Wordnik.com.  [The Continental Monthly, Vol. 3, No. 1 January 1863 Devoted To Literature And National Policy] Reference

Difficult to imagine Pearl jam warbling in French.    From Wordnik.com.  [Dining On Goose, Talking Turkey] Reference

Linnets and thrushes were warbling among the trees.    From Wordnik.com.  [Byeways in Palestine] Reference

The trio looked at the glass as made a warbling sound.    From Wordnik.com.  [The Impossible Man - Ep.6: Step into the Squared Circle] Reference

What laughter, what merry, bird-like warbling of voices!.    From Wordnik.com.  [French and Oriental Love in a Harem] Reference

Though saft the sang o 'simmer winds, the warbling o' the stream.    From Wordnik.com.  [The Modern Scottish Minstrel, Volume V. The Songs of Scotland of the Past Half Century] Reference

There's a warbling waggoner in it, and his team jingling their bells.    From Wordnik.com.  [The Violin Its Famous Makers and Their Imitators] Reference

And whilst she was warbling the door of the salle opened and in walked.    From Wordnik.com.  [Despair's Last Journey] Reference

 The warbling, caroling, tweeting and trilling were a caterwaul of happiness.    From Wordnik.com.  [Animal Park (Part II)] Reference

He heard in his mind a boy's warbling battle cry, and felt a deep pang of sadness.    From Wordnik.com.  [The Saracen: The Holy War] Reference

They are warbling words to music, but they are not singing, for the meaning is not there.    From Wordnik.com.  [Spirit and Music] Reference

During opener Half Asleep, the drums almost drown out Alejandra Deheza's gentle warbling.    From Wordnik.com.  [School of Seven Bells] Reference

It was Nicetas's turn, and he flew past the target with his warbling scream, standing in the stirrups.    From Wordnik.com.  [The Saracen: Land of the Infidel] Reference

On disc four, there's a touching home recording of the young Sean warbling "With a Little Help From My Friends.".    From Wordnik.com.  [Imagine All The Outtakes] Reference

There was lots of topiary involved, I seem to remember, and the singer from M-People did some unnecessary warbling.    From Wordnik.com.  [Lou Reed, SuBo and Simon Cowell: pop's unlikeliest threesome] Reference

Faceplant (Fitzgerald) was the drummer, obviously, Isaiah (Tomahawk) played bass, and (Matthew) Manhattanwas warbling.    From Wordnik.com.  [The Spaceman and the Venusian Vampire Vixens] Reference

I've been collecting albums for years and once in a while like to listen to the scratchy tunes warbling on my turntable.    From Wordnik.com.  [Bedbugs] Reference

The warbling of birds in the green bowers of bliss, which she occasionally heard, brought no tidings of gladness to her.    From Wordnik.com.  [Clotelle; or, the Colored Heroine, a tale of the Southern States; or, the President's Daughter] Reference

It's that weird, warbling Arabic music, but I can never tell if it's just a recording, or if someone is actually singing.    From Wordnik.com.  [From the Twin Towers to Fallujah] Reference

They know I dearly love the sunshine, and are calling me out into the midst of it; I hear them every day warbling so happily.    From Wordnik.com.  [Aunt Judith The Story of a Loving Life] Reference

At the summit of his ascent, he hovers about with irregular motions, chirping a medley of broken notes, like imperfect warbling.    From Wordnik.com.  [The Atlantic Monthly, Volume 04, No. 22, August, 1859] Reference

So far as she had known, none of the Pritchards had sung, and it was difficult to fancy Elsie's mother warbling a ditty of that sort.    From Wordnik.com.  [Elsie Marley, Honey] Reference

The birds were warbling their sweetest notes in the mulberry and walnut trees, and the hum of the bees were heard around the flowers.    From Wordnik.com.  [A California Girl] Reference

Persimmon Bill laughed at the look of wonder in the face of his visitor, and with his hand to his mouth, gave a shrill, warbling cry.    From Wordnik.com.  [Wild Bill's Last Trail] Reference

Male birds charm their mates by warbling, and parrots seem to take delight in hearing the piano played, or in listening to vocal music.    From Wordnik.com.  [Primitive Psycho-Therapy and Quackery] Reference

The Greek boy stood up in the saddle, and rode down the field with a warbling scream that was a perfect imitation of a Bedouin war cry.    From Wordnik.com.  [The Saracen: Land of the Infidel] Reference

"From the mountain's warbling fount I come," she chanted, with her eyes fixed on the words, but she played as if she were reading notes.    From Wordnik.com.  [The Beth Book Being a Study of the Life of Elizabeth Caldwell Maclure, a Woman of Genius] Reference

Reddy's too-oft maligned Titian locks, Hippy began a lively warbling which had nothing in common with the tinkling melody of the mandolin.    From Wordnik.com.  [Grace Harlowe's Golden Summer] Reference

Can't you see it: He busts in just when Swift's warbling begins to hurt, and delivers to West a verse or two from "F--- You," the kiss-off to end all kiss-offs.    From Wordnik.com.  [The Five Craziest Things That Could Happen at the 2010 VMAs] Reference

Miss Dawson was warbling to herself, with rather shrill-throated gaiety, whisking her full skirt among the bamboo tables, when Lucilla returned to the tea-room.    From Wordnik.com.  [A Sheaf of Corn] Reference

The sky was a pale red as far as the horizon, all nature wore a dreary aspect, and the most profound silence prevailed: not even the warbling of a bird was to be heard.    From Wordnik.com.  [A Book of Discovery The History of the World's Exploration, From the Earliest Times to the Finding of the South Pole] Reference