Male Quality and Polygyny: The "Sexy Son" Hypothesis Revisited

Recent studies by Weatherhead and Robertson (1977a, 1977b, 1979) ostensibly show that male quality is an important variable affecting female mating choices in polygynous birds. Here I show that their evidence is open to alternative interpretations and hence is inconclusive. I point out several problems that arise when interpreting evidence pertinent to testing their model and discuss the available evidence in light of those problems. The best experimental and correlative data comes from red-winged blackbirds, and an analysis of those data suggests that female redwings probably base their mate choices largely on territory quality. Current evidence shows that territory quality is an important basis of female mating choices but neither proves nor disproves the importance of male quality.