After androgen implants, territorial red grouse cocks sang more than before, had more encounters with neighbors and chased hens more, and did so more than unimplanted cocks. They moved more often on to adjacent territories, and took ground there despite the neighbors being initially dominant. Androgen-implanted non-territorial cocks challenged territorial cocks and eventually got small territories despite losing most encounters. After an estrogen implant, a territorial cock with a big territory and 2 hens was deserted by hens, sang less, had fewer encounters with neighbors and eventually gave up his territory.