Animals interact with nutrient cycles by consuming and depositing nutrients, interactions that are studied in the separate fields of nutritional ecology and zoogeochemistry. Recent theoretical work has begun bridging these disciplines, highlighting that animal-driven nutrient recycling could be crucial in helping animals meet nutritional needs. When animals exhibit site fidelity, they consistently deposit nutrients, potentially improving vegetation quality. We investigated this potential feedback by analyzing changes in forage nitrogen stocks following simulated caribou calving. We found that forage nitrogen stocks increased after two weeks and remained elevated after one year, a change due to an increase in forage quality but not quantity. We thus highlight a positive zoogeochemical feedback whereby caribou deposit nutrients during calving that become bioavailable during lactation and provide evidence that site fidelity creates a biogeochemical boomerang in which animals deposit nutrients that can be reused at a later time.