Which characteristics might selection favour as cues of female choice of mate in Red-winged Blackbirds?

Abstract

In this study, we investigated potential cues determining choice of mate by female Red-winged Blackbirds (Agelaius phoeniceus) by examining male and nest-site characteristics that (i) affect the reproductive success of females, (ii) can be assessed by females prior to mating, and (iii) vary among potential mates, in 1983–1985. The 17 characteristics considered reflected the accessibility of redwing nests to mammalian predators and to Marsh Wrens (Cistothorus palustris), the importance of cooperation between female redwings in nest defense, and the paternal quality (feeding and defense of nestlings), genetic quality, physical condition, and size of redwing males. Only 4 characteristics, distance to nearest wren nest, distance to nearest simultaneously active conspecific nest, height of vegetation supporting the nest, and nest defense effort of males, met all of the above criteria in at least 1 year. Of these, proximity to wren nests appeared to satisfy the requirements most consistently in time and space, and thus might be the most likely to affect female redwing choice of mate. However, experimental manipulations are needed to ascertain whether any of these characteristics are cues of female mate choice in Red-winged Blackbirds.