Old female reed buntings (Emberiza schoeniclus) increase extra-pair paternity in their broods when mated to young males

Abstract

SummaryIn birds, females are generally assumed to determine whether extra-pair copulations occur, and thus most studies on extra-pair paternity (EPP) have focussed on female preference for male traits, whereas female traits have been largely neglected. However, the occurrence of EPP is likely to be a result of behavioural interactions (e.g., mate guarding by the social male and escaping mate guarding by the female), and may be related to individual experience, which is expected to increase with age. We investigated the effect of age on levels of EPP in reed buntings Emberiza schoeniclus, a socially monogamous passerine with extremely high levels of extra-pair young (more than 50% of offspring). In broods of older males the rate of cuckoldry declined, which is in agreement with our previous finding that older males are more successful, either through female choice or through male experience. In contrast, older females tended to increase the level of extra-pair paternity in their broods. When including the age of the partner, we found that young males, but not old males, were cuckolded more by old females than by young females. The increase in EPP with female age is not likely to be due to disassortative mating with respect to age, an increased capacity of older females to raise a brood without male help, nor a male preference for older females. With age, males nor females changed their share in parental effort. We suggest that with increase in age, females become more choosy when selecting the male that sires their offspring, or alternatively, become more experienced at circumventing paternity assurance tactics of young males.

Interactive effects of male and female age on extra-pair paternity in a socially monogamous seabird

“…It is more likely that young females assigned paternity to EP males older than their partners to obtain better genes for their offspring, consistent with predictions from life history theory (Manning 1985;Kokko 1998;Brooks and Kemp 2001). Alternatively, young females' decline in EPP with increasing partner age could be due to diminishing opportunities for this indirect benefit as the availability of relatively older EP sires declines or to improvement in mate guarding with male age (Gowaty and Bridges 1991;Bouwman and Komdeur 2005). Young females' EP sires were not older than the average male breeder in the study plot, but five of the six were older than the males they cuckolded, implying that EP sires were selected not for their absolute age but for their relative age (consistent with good genes theory; Kempenaers and Dhondt 1993).…”

“…Nonetheless, they suggest that other avian species may have diverse male/female age interactions. In pied flycatchers (Ficedula hypoleuca) and coal tits (Parus ater), EPP appears most likely when an old female pairs with a young male (Rätti et al 2001;Dietrich et al 2004) and, in reed buntings (Emberiza schoeniclus), when old females have more EP chicks than young females and they cuckold young males (but not old males) more often than do young females (Bouwman and Komdeur 2005). The generality and adaptiveness of the booby pattern need to be explored by documenting patterns of paternity across the full natural age spans of other vertebrates, taking ages of all three players into account.…”

“…These interaction effects raise the possibility that old female birds, in particular, might maintain their fertility or offspring quality by avoiding pairing with old males with senescent sperm traits and germ cells. Indeed, there is some evidence that female age affects the incidence of EPP in birds (Stutchbury et al 1997) and can interact with male age (Rätti et al 2001;Dietrich et al 2004;Bouwman and Komdeur 2005). However, interacting effects of male and female age on EPP across the age span of long-lived birds have not been investigated (although see Lubjuhn et al 2007).…”

Promiscuous mating produces offspring with higher lifetime fitness

“…less than 24 h between firstand last-hatched), and thus there is no detectable size difference between nestlings based on hatching order [43]. Similarly, while older females tend to be both better parents and more likely to engage in extra-pair mating [44][45][46], our findings remained significant when controlling for F 0 maternal age (electronic supplementary material, tables S3-S6). In fact, males (but not females) produced by older mothers were actually less successful, contrary to the predicted relationship (electronic supplementary material, table S4).…”

Individual variation and environmental context in avian life-history evolution: An experimental approach using mountain bluebirds (Sialia currucoides).

“…Year was included as a categorical covariate in initial models to account for possible annual variation in patterns of paternity. Clutch initiation date (CID) is correlated with female age and/or quality in many songbirds, including my population of bluebirds (see Chapter 4), and older females or those in better condition may be more likely to seek extrapair fertilizations (Bouwman and Komdeur 2005); males paired with high-quality or older females that initiate breeding earlier in the season may therefore be more likely to lose paternity in their own nest. Alternatively, females that initiate breeding earlier in the season may be paired with higher quality social mates, and may therefore be predicted to be less likely to seek EPF.…”