1. King J. R., in Avian Energetics, , Paynter R. A., Ed. (Publication 15 of the Nuttall Ornithological Club, Harvard Univ., Cambridge, Mass., 1974), pp. 4–70;
2. Wiley H., Q. Rev. Biol. 49, 201 (1974).
3. About 2 percent of bird species are polygynous (8 percent of nidifugous species and 1 percent of nidicolous species), according to Lack D. [Ecological Adaptations for Breeding in Birds (Methuen, London, 1968), pp. 149–150].
4. Verner J., Willson M. F., Mating Systems, Sexual Dimorphism, and the Role of Male North American Passerine Birds in the Nesting Cycle (Ornithological Monogr. 9, American Ornithologists’ Union, Washington, D.C., 1969), pp. 1–76.
5. Verner J., Evolution 18, 252 (1964);