Two species of cuckoo doves live in a group of islands off the coast of New Guinea. Of 33 islands, 14 have one species, 6 have the other, 13 have neither, and none has both. What might best explain this? The two species of birds could _____. (see textbook sections 37.1-13 for reference)
A. be on different trophic levels
B. have a mutualistic relationship
C. have similar niches
D. have different niches