Humans have lived with animals since prehistoric times. Since human domestic environments have started expanding, a new typology of animals has emerged, feral animals : they are the animals living in our domestic environments, and they are neither domestic nor wild (wolves, spiders, pigeons, etc.). How can design encourage a diplomatic coexistence between humans and feral animals ? This project is focusing on gardens, where feral animals can be not only devastating, but also helpful. Co.bocage invites great tits and humans to coexist and to collaborate. Great tits turn into garden’s assistants and help developing spontaneous hedges, which will turn into biodiversity refuges. Co.bocage was designed by taking into account the needs of great tits and the needs of users. It is also concerned with all the required facilities for the growth of spontaneous hedges.