In the early 1970s, drs. peter and rosemary grant began studying darwin's finches and significantly extended our knowledge of the different species and their behaviors. on the island of daphne major, the grants focused on three closely related species within the genus geospiza. the table summarizes some of the distinguishing traits of each species. the grants did experiments that demonstrated that each species on daphne chooses mates of their own species over other species. on rare occasions, species will hybridize and create viable offspring, but this is extremely infrequent. the three species are still distinct enough that they are considered separate species. in 1981, a single bird appeared on daphne that was not any of the three species described above. the grants called him "5110." watch the video to learn more about 5110.