Greenfeather Bird Supply's Rat Enrichment Tunnel is designed to encourage what a rat does best: explore and forage, the company reports. The ends of the tunnel are covered, forcing a rat to work its way inside. Stuffed in layers within the natural bamboo tunnel are pinecones containing pine seed or pine nuts, nubbies, organic apple sticks to chew, paper sticks to peel, natural shredded fibers for nesting and a natural seed-filled sunflower head, the company states. No pesticides, glues or toxins are used in the construction. The U.S.-made tunnel is refillable and becomes a great hideout, the company adds.