What happenes when Gertrude mcfuzz swallows a berry in the book mcfuzz?

In the book "McFuzz", Gertrude McFuzz swallows a pinecone, not a berry. After swallowing the pinecone, Gertrude's tail feathers begin to grow uncontrollably. They become so long that they weigh her down and make it difficult for her to fly. Gertrude eventually seeks help from a wise old owl, who advises her to chew on a piece of gum to remove the pinecone. The gum sticks to the pinecone and allows Gertrude to successfully remove it, restoring her tail feathers to their normal size and enabling her to fly freely again.