Polygyny in Indigo Buntings: A Hypothesis Tested

Abstract

A test ofa modelfor the evolution ofavian polygyny revealed that 10 percent ofmale indigo buntings had two mates simultaneously and some had none. Old males acquired territories first, and yearlings moved into leftover space. Yearling males that obtained mates tended to form brief, monogamous bonds. Females mated to polygynists

The Evolution of Mating Systems in Birds and Mammals

“…This occurs in Australian bell-magpies (Gymnorhina) (Wilson, 1946;Robinson, 1956), great-tailed grackles (Quiscalus mexicanus) (McIlhenney, 1937), oropendolas and caciques (Icteridae) (Chapman, 1928;Skutch, 1954;Tashian, 1957;Drury, 1962), red-winged blackbirds (Orians, 1961), polygynous weaver finches (Ploceinae) (Crook, 1964), dickcissels (Spiza americana) (Zimmerman, 1966), corn buntings (Emberiza calandra) (Ryves and Ryves, 1934), and indigo buntings (Passerina cyanea) (Carey and Nolan, 1975;Carey, 1977). The result is a lowering of the fitness curves for all females and a narrowing of the difference in success between monogamous and lowranking females on any given territory.…”

“…More precisely, predictability refers here to the probability that the rank ordering of habitats in terms of their quality will remain the same within any specified time interval during the breeding season. aData based on Wittenberger, 1976a; Menum rwvaeholJandiaR was deleted because matings are apparently promiscuous instead of polygynous (Lill, personal communication); Passerina cyanea and Cistothorus platensis were added on the basis of Carey and Nolan (1975), Carey (1977), andCrawford (1977) and Calamospiw melarwc01Ys was added on the basis of Pleszczynska (1978). b Agelaius phoeniceus has a clumped nesting distribution in marshes and a dispersed nesting distribution in uplands, but its preferred habitat is marshes so it is included in this category.…”

Shift in red fox, Vulpes vulpes, mating system associated with El Niño in the Bering Sea

“…The cost of sharing a male with a second female may be exceeded by the benefits which include occupying a superior territory, mating with a superior male, or cooperatively rearing offspring with another female (Emlen & Oring 1977;Wittenberger & Tilson 1980). Shifts from monogamy to facultative polygyny among avian species have been documented under ecological conditions predicted by the polygyny threshold model (Martin 1971;Holm 1973;Carey & Nolan 1975;Wittenberg 1976;Pleszczynska 1978).…”

Polygyny as an Adaptive Alternative to Monogamy in Two Species of Dippers: Cinclus Mexicanus and Cinclus pallasii

“…Obvious sexual dimorphism in the form of showy feathers or colors does not exist in Cinclus, and probably will not evolve, as was suggested by Carey and Nolan (1975). Because of their method of feeding, showy feather would hinder the male to such a degree as to make him less fit evolutionarily.…”