Answer: The bark on the tree was just a little bit softer
The movie-version went as follows:
"If only, if only," the woodpecker sighs,
The bark on the tree was a soft as the skies.
While the wolf waits below, hungry and lonely,
He cries to the moo-oo-oon,
If only, if only."
The one from the book went as written below:
"If only, if only," the woodpecker sighs,
The bark on the tree was just a little bit softer.
While the wolf waits below, hungry and lonely,
He cries to the moo-oo-oon,
If only, if only."