Male plumage, paternal care and reproductive success in yellow warblers, Dendroica petechia

Using morphological or behavioural features correlated with paternal care, females can, prior to mating, assess the potential parental contribution of males. As a first step in a study of female mate choice in yellow warblers, this study was designed to examine the importance of paternal care by males of differing chest striping. Contrary to a previous report, paternal care was not negatively correlated with male chest striping. Paternal care was highly variable between individuals. Females did not compensate for experimentally induced reductions of paternal care, which resulted in significantly reduced nestling growth. Therefore, in the absence of alternative mating opportunities, males must maintain their contributions of paternal care or pay the cost of reduced fitness. ? 1996 The Association for the Study of Animal Behaviour In species with biparental care, females may benefit by choosing mates who provide suitable paternal care. Searcy (1979) stated that if female mate choice is to be considered adaptive, the traits selected in males must (1) affect the females’ fitness, (2) have enough variation for selection to be possible and (3) be reliably indicated by some cue that females can observe at the time of choice. Searcy’s third criterion is especially important for females trying to choose males on the basis of paternal care. Behavioural or morphological male traits correlated with paternal care could be used by females for these purposes. There are several instances in which paternal care is correlated with behavioural traits that females can assess before mating. The singing rate of stonechats, Saxicola torquata, correlates with paternal care, but not with greater fledging success (Greig-Smith 1982). Male courtship rate in damselfish, Stegastes partitus, correlates with the number of eggs received from females and the survival of the eggs (Knapp & Kovach 1991). The frequency of courtship feeding correlates with the amount of paternal care provided in herring gulls, Larus argentatus (Niebuhr 1981), as well as with the total weight of the clutch and brood and the number of nestlings fledged in common and arctic terns, Sterna paradisaea (Nisbet 1973). In red-winged blackbirds, Agelaius phoeniceus, courtship time correlates with the amount of paternal care provided (Searcy & Yasukawa 1981; Eckert & Weatherhead 1987). Morphological traits correlated with paternal care could also affect female mate preferences. Among biparental fish, females sometimes prefer larger males, presumably because these males take a more active role in guarding the eggs or brood (Downhower & Brown 1980; Grant & Colgan 1983; Keenleyside et al. 1985; Bisazza & Marconato 1988; Côte & Hunte 1989). In great tits, Parus major, female choice is partially based on the size of the male black chest stripe (Norris 1990a); Norris (1990b) argued that this preference occurs because the size of the stripe correlates with male nest attentiveness and nestling fledging weight. Studd & Robertson (1985a) compared yellow warbler males with different amounts of brown streaking on their chests and found that lightly streaked males visited their nests more often than did heavily streaked males. They also showed that heavily streaked males elicit more intense responses from territorial males, react more intensively while defending their territories, spend more time on their territories (Studd & Robertson Correspondence: G. A. Lozano, Department of Biology, McGill University, 1205 Dr Penfield Ave., Montreal, Quebec H3A 1B1, Canada (email: [email protected]. mcgill.ca). 0003–3472/96/020265+08 $12.00/0 ? 1996 The Association for the Study of Animal Behaviour