The forest version of "Beaver Fever", performed by Norbert and Daggett Beaver, is a song from the episode of the same name. It was played on homemade instruments near the forest for Norb and Dag's friends, but got cut short due to the latter's clumsiness.
Norbert: In the day, he bites down trees
and chews away the bark
But he really starts to work it
after it gets dark
Daggett: He's got the beaver fever
Oh, yeah, ooh.
BMI Work #4396727