Forsh - doesn't fit the rhythm of the song. Try:

Green is the grass and sprung is the spring
All the little birds are on the wing

But I think that's just plain absurd
The bird ain't on the wing, the wing's on the bird

Cluck old hen, cluck and scratch
One of them eggs may someday hatch

A wooly chick had my old hen
Been foolin' around with the sheep again.