Sentence:  Marta's gander was a magnificent snow-white bird: the object of terror to foxes, children and dogs. She had reared him as a gosling; and whenever he approached, he would let fly a low contented <WSD>burble</WSD> and sidle his neck around her thighs. 
Meaning of the word marked with <WSD> tags:  A bubbling, gurgling sound, as of a creek.