Extra-pair Behaviour Research Articles

Breeding synchrony and extrapair fertilizations in two populations of red-winged blackbirds

We tested the relationship between synchrony of breeding and the frequency of extrapair fertilizations (EPFs) in two populations of red-winged blackbirds known to differ in female extrapair behavior. We found no association between the number of simultaneously fertilizable females (temporal neighbors) and EPF rate in either population, although a significant difference between populations in the direction of this relationship (positive where females initiated extrapair copulations and negative where males initiated them) suggested a modest difference in the influence of synchrony. Males losing offspring to EPFs tended to have more fertilizable females at that time than the actual sires in some analyses but not in others. We also tested several assumptions underlying two competing hypotheses for the effects of synchrony. We found no evidence that females pursued extrapair copulations more often when other females were synchronous. Rather, females were more likely to gain EPFs with extrapair males whose social mates were not yet building their nests. Synchrony also did not consistently affect male pursuit of extrapair copulations or achievement of EPFs. These results suggest that timing of breeding has some effects on extrapair activity, but that those effects are both relatively weak and influenced by other factors that vary between years or populations.

Reproductive synchrony and extra-pair mating strategy in a socially monogamous bird,Dendroica petechia

Depending on the circumstances under which extra-pair mating occurs, theory makes opposing predictions about how reproductive synchrony should influence extra-pair paternity. This study investigated which sex initiated extra-pair mating in the yellow warbler, whether extra-pair behaviour and extra-pair paternity were related to reproductive synchrony, and whether synchrony affected the mating success of all males equally. Observations and captures of individuals making territorial intrusions indicated that males initiated extra-pair mating. Spatial patterns of male territorial intrusions and of extra-pair paternity were similar. Males’ extra-pair activity was reduced when their social partner was fertile. More offspring were sired by the extra-pair male when the female nested asynchronously with that sire's social mate. Neither population-wide synchrony, nor synchrony with neighbours, however, seemed to predict the incidence of extra-pair parentage or the identity of the sire, indicating factors other than synchrony were also important. Males with more breast streaking (a plumage ornament) were more successful as extra-pair sires, and were least affected by the constraint of synchrony. Larger males were less often cuckolded, and achieved extra-pair success mainly when their partner was not fertile. Thus, male yellow warblers apparently use different mating tactics depending on their plumage and size. More generally, the results suggest how mating strategies are affected by which sex initiates extra-pair mating and by the relative contributions of within-pair and extra-pair paternity to total reproductive success.

Reproductive Anatomy of the Reed Bunting: A Species Which Exhibits a High Degree of Sperm Competition through Extra-Pair Copulations

The morphology of the reproductive organs of both male and female Reed Buntings (Emberiza schoeniclus) are described in relation to the high level of sperm competition exhibited by the species as a result of extra-pair copulation behavior. In males, the volume of the cloacal protuberance in relation to body weight was 26.7 mm 3 g -1 , which is relatively large for a socially monogamous passerine. The weight of the testes was 23% greater than that expected for a bird of comparable size, and the spermatozoa were among the longest recorded for any avian species (mean length = 291 μm). The morphology of the female tract also showed adaptations associated with a high level of sperm competition: the sperm storage tubules were extremely long (mean length = 865 μm).

Intra- and extra-pair behavior and initial clutch success in captive zebra finch colonies.

Annals of the New York Academy of SciencesVolume 807, Issue 1 p. 549-551 Intra- and Extra-Pair Behavior and Initial Clutch Success in Captive Zebra Finch Colonies JOANNE OLIVA-PURDY, JOANNE OLIVA-PURDY aMammal Department Baltimore Zoo Druid Hill Park Baltimore, Maryland 21217Search for more papers by this authorCHERYL F. HARDING, CHERYL F. HARDING bBiopsychology Program Hunter College New York, New York 10021Search for more papers by this author JOANNE OLIVA-PURDY, JOANNE OLIVA-PURDY aMammal Department Baltimore Zoo Druid Hill Park Baltimore, Maryland 21217Search for more papers by this authorCHERYL F. HARDING, CHERYL F. HARDING bBiopsychology Program Hunter College New York, New York 10021Search for more papers by this author First published: 17 December 2006 https://doi.org/10.1111/j.1749-6632.1997.tb51965.xRead the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Volume807, Issue1Integrative Neurobiology of Affiliation, TheJanuary 1997Pages 549-551 RelatedInformation

The insemination window provides a distorted view of sperm competition in birds

The aim of this study is to identify and rectify a misunderstanding about the optimal timing of inseminations in birds. In species laying clutches of more than one egg, a copulation during the hour following egg-laying can result in sperm reaching the site of fertilization in time to fertilize the next egg to be laid. Cheng et al. (1983) referred to this period as the insemination window and proposed that it was `an especially favourable period' for males to obtain extra-pair copulations. As stated in their paper, this is true only in terms of the next ovum to be fertilized, but subsequent authors assumed that the insemination window represents a general peak in female fertility and have made predictions about the optimal timing of extra-pair behaviours and paternity guards relative to it. Far from being a general peak in female fertility, we show by a re-analysis of Cheng et al.'s data and by using published information on the domestic fowl Gallus domesticus, turkey Gallopavo meleagris and Muscovy duck Cairina moschata, that inseminations either just after egg-laying or just before it are much less likely overall to result in fertilization than inseminations made at other times. The reduced efficacy of inseminations made close to the time of egg-laying occurs because the retention of sperm by females inseminated at this time is low. The fact that inseminations made around the time of egg-laying in the domestic fowl, turkey and Muscovy duck have a reduced probability of fertilization is consistent with the fact that very few wild birds, even those in which sperm competition is intense, alter their copulation or mate guarding behaviour during the insemination window.

DNA fingerprinting reveals female preference for male parental care in Savannah Sparrows.

According to sexual selection theory, females choose mates to ensure access to high quality resources, male parental care, or good genes. This last hypothesis has been hotly debated on both theoretical and empirical grounds. In contrast, female preference for male parental care has received less attention, primarily because the potential benefits of paternal effort seem obvious. The fitness relations are less clear in double-brood species, however, because females can base mating decisions on their prior experience with male parental care. Here, the extent of male parental care delivered to first-brood offspring may indicate male genetic quality and/or be the target of female manipulation via her subsequent mating fidelity. In Savannah Sparrows (Passerculus sandwichensis), multi-locus DNA fingerprinting of 203 adults and young revealed substantial female infidelity in first and second broods: overall, 24 of 80 first-brood young (30%) and 13 of 80 second-brood young (16.3%) were the product of extra-pair fertilizations. Among 12 females altering fidelity between broods, absolute male feeding rate to first-brood offspring was a strong, positive predictor of change in female fidelity. Because the extent of male parental care reflects a male's viability, the data support a 'good-genes' interpretation.

Helpers liberate female fairy-wrens from constraints on extra-pair mate choice

In cooperatively breeding superb fairy-wrens (Malurus cyaneus), all males contribute to the feeding and defence of young. Despite the expectation that such paternal care should be directed only to relatives, DNA fingerprinting revealed that most offspring (76%, 138 out of 181) were sired by extra-group males that contributed no care, and that almost all broods (95%, 38 out of 40) contained young sired by extra-group fathers. This is the highest known incidence of cuckoldry. This remarkable mating system is produced by female control of fertilization and consistent preference for certain extra-group male genotypes. This choice leads to the production of sons that also gain extra-group fertilizations. One constraint on the extra-pair mate choice of females is the level of parental assistance received from males. Males living in pairs contribute relatively more parental care and are more likely to gain paternity in one of their broods (85%, 11 out of 13) than dominant males in multi-male cooperative groups (30%, 8 out of 27). In groups helpers compensate for the lower parental assistance of dominant males, so the total feeding rate is similar between pairs and groups. This suggests that females allow males in pairs more paternity to ensure their assistance with parental care. Helpers provide an alternative source of paternal investment, and allow females to express unrestricted mate choice. Mating options for females in other species with female control of fertilization may also reflect a trade-off between acquiring the genes of high-quality males for their offspring and parental care of those offspring.

A Case of Polyandry in the Blue Tit: Female Extra-Pair Behaviour Results in Extra Male Help

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Copulation and Mate Guarding in the Yellow-Billed Magpie Pica Nuttalli and a Comparison With the Black-Billed Magpie P. Pica

Abstract Yellow-billed magpies breed in loose colonies. Extra-pair courtship is frequent, and a comparison (I) between two adjacent areas with different inter-nest distances, and (2) with solitary, territorial European black-billed magpies, indicates that either an aggregated distribution of nests, or a relatively loose territorial system in yellow-billed magpies increases opportunities for extra-pair behaviour. Male yellow-billed magpies guard their partner by closely following them from five days before the first egg is laid. Pair copulations were infrequent, occurring 3 or 4 times per clutch, and mainly over days -5 to -3. Territoriality, which is most pronounced during the female's fertile period, may enable the male to guard his partner while simultaneously foraging to provide her with food.

Extra-pair mating in the spotted sandpiper: a female mate acquisition tactic

Extra-pair mating behaviour was studied in the spotted sandpiper, Actitis macularia, a sex-role reversed, polyandrous shorebird, in which females are larger than and socially dominant to males. On a population basis, intra-pair mating events (0.39 events/h) exceeded extra-pair events (0.05 events/h) by about a factor of 10; 15% ( N=26) of extra-pair events were copulations. Extra-pair events were not synchronized with the fertile period of females. Extra-pair mating events were more likely to end in copulations when males were either unpaired or paired to females that had not started laying a clutch compared with males that were incubating or paired to a laying female. Overall, males moved further than females during extra-pair events, but distance moved was associated with male reproductive status. Within each sex, extra-pair events were not randomly distributed among individuals in most years, indicating that few individuals were responsible for most extra-pair events. For both sexes, extra-pair behaviour was correlated with number of breeding attempts annually and was unrelated to individual morphology and breeding experience. Extra-pair events increased the likelihood that females would subsequently pair with the males concerned. It is proposed that extra-pair mating events in spotted sandpipers in part serve the novel function of establishment and maintenance of social relationships that may lead to subsequent pair formation and mate acquisition, a pattern correlated with the species sex-role reversed mating system.