"Polly had, and often felt like a little wood-bird shut up in a gilded cage."
"When Siegfried returns with ring and helmet, he is again warned by the voice of a wood-bird, not to trust in Mime."
"-- Stretching himself under the linden-tree to repose after that day's hard work, he again hears the voice of the wood-bird, which tells him of a glorious bride, sleeping on a rock surrounded by fire; and flying before him, the bird shows Siegfried the way to the spot."