Among all the zoological species, birds are the easiest to observe and study. Their diurnal habits, the songs, and visual features make them conspicuous. These characteristics have made birds one of the bestknown animal groups even though ornithologists do not make up a large community among zoologists. For Ernst Mayr, an ornithologist who has made significant contributions that go beyond his own field, the accessibility of birds to research has allowed ornithologists to make important discoveries in several new fields of biology, ranging “from new systematics and speciation research to endocrinology and behavioral biology.”