When the decomposer decomposes the organic substances than they are taken by plants in the form of nutrition and minerals. Likewise, the food prepared by the plants are taken by animals and the nutrition is recycled.
The oxygen and carbon dioxide cycle is also recycled. When the animals releases carbon then the plants take it and gives out the oxygen. In this way oxygen and carbon dioxide cycle is also maintained in nature.
Answer take one piece of the squirrels diet away and see if anything has changed, if not give it that part back and take something else. repeat till change happens if nothing happens then change hypothesis