Age-Related Variation in Mate-Guarding Intensity in the Bluethroat (Luscinia s. svecica)

Female extra‐pair copulations (EPCs) have selected for male paternity guarding strategies in many bird species. In the bluethroat, Luscinia s. svecica, males guard their mates closely during the last 2 d before the start of egg laying, but there is great individual variation in the intensity of mate guarding. Here we show that some of this variation is related to male age. Old males guarded their mates with much lower intensity and sang more than young males, although the latter difference was not statistically significant. Controlling for male age, male and female coloration and size were not significantly related to the intensity of mate guarding. We have previously shown that young and old males had a similar paternity loss in their own broods. On the other hand, old males were far more successful than young males in achieving extra‐pair fertilizations. These patterns suggest that young and old males have different trade‐offs between preventing paternity loss in own nest and gaining paternity in others, because male skills in obtaining EPCs improve with experience and/or because of female preferences for old males as copulation partners. There were no significant relationships between paternity and male mate‐guarding behaviour during the fertile period, indicating that mate guarding is not a very effective paternity‐assurance strategy in the bluethroat.     

Part-Time Mate Guarding Affects Paternity in Male Reed Buntings (Emberiza schoeniclus)

Male mate guarding by close following has been reported in many socially monogamous bird species and is generally believed to function as a paternity guard. Many aspects of the dynamics and effectiveness of this behavior are still however poorly understood. Here, we describe the temporal variation in mate guarding behavior in male reed buntings (Emberiza schoeniclus) with a particular focus on how males allocate their mating effort between mate guarding and extrapair mating in a context of intense sperm competition. In our highly synchronous study population most males have to balance the simultaneous and mutually exclusive demands of mate guarding and seeking extrapair copulations (EPCs). We found that males frequently switched between guarding their mates and performing intrusions to neighboring territories. Both activities seemed to have significant fitness payoffs, as male mate guarding effort had a positive effect on paternity, and a large fraction of extrapair fertilizations occurred during the days when the sire guarded its own female. The reed bunting is thus an example of how discontinuous or part‐time mate guarding can still be effective in securing paternity. Female reed buntings were not particularly active in initiating EPCs as they never were observed performing extraterritorial forays. We argue that the absence of female‐initiated EPCs is a prerequisite for males to trade mate guarding against seeking EPCs. Otherwise, if females circumvent male mate guarding by timing their EPCs to periods of male absence, males should guard their mates almost continuously or rely on alternative paternity guards.     

Mate Guarding in Male Dall's Porpoises (Phocoenoides dalli)

Mate guarding, whereby a male closely attends and defends a fertile female from extra‐pair matings, is one mating tactic males of many species use to protect their paternity. Although female defense occurs in many species of terrestrial mammal, comparable examples among cetaceans are largely absent, potentially as a result of the wide dispersion and mobility of females and their prey. Here, we investigate whether the close association of individual male Dall's porpoises with individual females during the breeding season is consistent with mate guarding. As mate guarding is predicted to be costly, and in other taxa is often associated with a reduction in foraging efficiency, we also examine whether males trade‐off this activity with time at depth. Males maintained longer associations and closer distances with female partners than with male ones. They also surfaced in greater synchrony with, and more often approached, their female partners than male ones. In contrast to males with male partners, males paired with females engaged in agonistic interactions with other adult males, and infrequently affiliated with extra‐pair individuals. These data suggest males are actively attempting to maintain their associations with females, while also acting to reduce female extra‐pair copulations and increase their own paternity. Guarding males also undertook shorter dives than non‐guarding males, suggesting that they trade‐off time at depth with guarding. Such a trade‐off is likely to involve a reduction in foraging opportunities, due to a decrease in time spent at foraging depth. Mate guarding in this species may be facilitated by the relatively smaller size and decreased mobility of newly calved, estrous females, particularly if females also benefit from guarding.     

Factors influencing mate guarding and territory defence in the stitchbird (hihi)

Socially monogamous male birds are predicted to maximise their reproductive success by pursuing extra-pair copulations (EPCs) while engaging in anti-cuckoldry behaviour such as mate guarding. In the stitchbird, Notiomystis cincta, high levels of forced EPCs and a high proportion of nestlings resulting from extra- pair fertilisations lead to the prediction that males of this species should exhibit intense paternity guarding behaviours. While studying an isolated stitchbird population on Tiritiri Matangi Island New Zealand (3636'S, 17453'E), I collected daily behavioural data throughout the breeding season from 15 males in 2000/01 and 27 males in 2001/02. In this study, male stitchbirds demonstrated clear paternity guarding by exhibiting: (1) an increased likelihood of being close to their mate during her fertile period, (2) an increased initiation of mate contact during her fertile period, (3) switching from site-specific territorial defence during the pre-fertile period to defending an area centring on the their female partners location during her fertile period, and (4) an increased following of the female to communal feeding sites outside the territory during her fertile period. For polygynous males, mate guarding and territorial defence were conditional on which of their females was fertile. Additional evidence supporting the hypothesis that mate guarding in this species is a form of paternity assurance, rather than protection from harassment, is that males protected their partner from harassment by other stitchbird males but did not intervene when females were harassed by male bellbirds, Anthornis melanura. While mate-guarding intensity in many species is conditional on the stage of female fertility, male stitchbirds also modified their behaviour depending on the location of the female and the rate of intrusions by extra-pair males. Resident males adopted a best-of-a-bad-job tactic when they were unable to locate their female by defending an area around her last known location. Furthermore, when the rate of intrusions by extra-pair males increased they traded-off the area they could defend within their territory against their ability to guard the female. Territory takeovers were uncommon, but when they did occur older males displaced younger males and healthy birds displaced sick ones. Contrary to the prevailing view that mate guarding is a male response to female infidelity, male stitchbirds appear to use mate guarding primarily to prevent paternity losses from forced EPCs. Future assessments of mate guarding function should consider the possibility that mate guarding involves a combination of conflict and co-operation between the sexes.     

Territorial intrusions and copulation patterns in red kites, Milvus milvus, in relation to breeding density

Two main paternity assurance strategies are generally found in birds: mate guarding and frequent copulations. The latter is expected particularly in species such as raptors that cannot guard their mates efficiently because of ecological constraints, such as frequent courtship feeding. I investigated the prelaying behaviour of red kites, in which the males courtship feed. I compared pair behaviour in situations of varying breeding density and simulated male territorial intrusions by presenting decoys. Males' certainty of paternity was likely to decrease with increasing breeding density, because of the proximity of other males and more frequent male territorial intrusions during the presumed fertile period. The percentage of time spent by males within their breeding territory during the prelaying period was positively related to the number of close breeding neighbours, suggesting territory surveillance and mate guarding. The kites copulated frequently and over a long period. Copulation frequency prior to and during laying increased with breeding density, and in isolated pairs in response to simulated male territorial intrusions. The results support the idea of paternity assurance through frequent copulations during the presumed fertile period of the female, and suggest that early copulation activity is related to functions other than fertilization, such as pair bonding or mate assessment. Copyright 2000 The Association for the Study of Animal Behaviour.     

Strategic mate‐guarding behaviour in ladybirds

Mate‐guarding behaviour is regarded as a means of increasing paternity share by reducing sperm competition. It is known to be a plastic response which varies with operational sex ratios and competitor presence in the vicinity. In a recent study, prolonged mating duration in Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae) has been found to incorporate mate‐guarding behaviour. The present investigation was conducted to assess its plasticity in the presence of competitors. The physical and chemical presence of competitors of both sexes at varying densities was provided to a pair of ladybirds, and their time to commence mating, latent period and mate‐guarding duration was observed. These were compared to a control treatment where other partners were absent. All treatments were conducted with sibling as well as non‐sibling competitors. It was our hypothesis that mate guarding would be increased in the presence of male competitors and would be reduced by female presence. The results revealed that while mate‐guarding duration was increased by the chemical presence of males it was decreased by their physical presence. The latter result was attributed to interference by other males who dislodge the mating male in order to access the female. Female chemical presence had no effect on mate guarding, while physical presence increased the duration of mate guarding. The reasons for the latter behaviour require further investigation. Responses were not significantly affected by the relationship between the focal pair and the competitor. The authenticity of the mate guarding in this ladybird is strongly affirmed by our results.     

Extrapair paternity as a cost of polygyny in the rock sparrow: behavioural and genetic evidence of the ‘trade-off’ hypothesis

We studied the association between extrapair paternity (EPP) rate and male mating status in the rock sparrow, Petronia petronia, a facultative polygynous species. Overall, 32.0% (58/181) of the chicks were not sired by the social father and 57.1% (24/42) of the broods contained at least one extrapair young. Polygynous males allocated less time to guarding their mate during her fertile period than monogamous males but did not differ in the time spent guarding their nest. Polygynous males were cuckolded more frequently than monogamous males (50.5 and 6.6% of the young, respectively) and their paternity loss was positively correlated with the degree of overlap between the fertile periods of their primary and secondary females. Paternity loss did not differ between primary and secondary broods of polygynous males and acquiring a second mate was possible only at the expense of paternity in both broods. Late broods contained fewer extrapair young, despite no significant seasonal trend in the time allocated by the male to guarding his mate. Male yellow badge size was not associated with paternity. Old males were cuckolded less frequently than first-year males, but male age had a minor effect on paternity compared with male mating status. Reproductive success (number of young fledged/year) did not differ between monogamous and polygynous males once paternity was accounted for. Together, these results suggest that mate guarding can be efficient in preventing cuckoldry, and that there is a trade-off between attracting an additional mate and protecting paternity in the rock sparrow, whereas male age and phenotype were, at best, fair predictors of paternity. Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour     

Sperm Competition in Humans: Mate Guarding Behavior Negatively Correlates with Ejaculate Quality

In species where females mate with multiple males, the sperm from these males must compete to fertilise available ova. Sexual selection from sperm competition is expected to favor opposing adaptations in males that function either in the avoidance of sperm competition (by guarding females from rival males) or in the engagement in sperm competition (by increased expenditure on the ejaculate). The extent to which males may adjust the relative use of these opposing tactics has been relatively neglected. Where males can successfully avoid sperm competition from rivals, one might expect a decrease in their expenditure on tactics for the engagement in sperm competition and vice versa. In this study, we examine the relationship between mate guarding and ejaculate quality using humans as an empirical model. We found that men who performed fewer mate guarding behaviors produced higher quality ejaculates, having a greater concentration of sperm, a higher percentage of motile sperm and sperm that swam faster and less erratically. These effects were found independent of lifestyle factors or factors related to male quality. Our findings suggest that male expenditure on mate guarding and on the ejaculate may represent alternative routes to paternity assurance in humans.     

Female collared flycatchers choose neighbouring and older extra‐pair partners from the pool of males around their nests

Extra‐pair copulation is common among passerine birds. Females might engage in this behavior to obtain direct or indirect benefits. They may choose extra‐pair males with larger ornaments, especially if they are costly to produce. Here we studied extra‐pair paternity in the collared flycatcher. Genetic analysis allowed us to identify the presence or absence of extra‐pair young in the focal nests, and to identify extra‐pair fathers. We also identified potential males available as extra‐pair sires around the nests of females who had extra‐pair young. First, we tested the relationship between paternity in own nest and ornament size (wing patch and/or forehead patch), morphological traits and age of social males and females. Second, we compared the same suite of traits among social mates, extra‐pair males and all potential extra‐pair mates. Finally, we investigated the effect of the size of ornaments on the distance between the social nest and that of nest the extra‐pair father. Contrary to our prediction, males with larger ornaments and longer wings lost more paternity in their nests. We also found that early breeders lost less paternity in their nests. Extra‐pair males were older and had longer wings than social and potential extra‐pair males. Females mainly obtained extra‐pair mates near their nests but the distance did not vary according to ornamentation. These results could potentially be explained by differences in mate guarding strategy as older males may be more experienced in guarding their mate and attract other females more easily. More data about mate guarding and prospecting are needed to increase our understanding of mechanisms underlying the extra‐pair paternity in birds.     

Mate guarding in the Seychelles warbler is energetically costly and adjusted to paternity risk

Males may increase their fitness through extra-pair copulations (copulations outside the pair bond) that result in extra-pair fertilizations, but also risk lost paternity when they leave their own mate unguarded. The fitness costs of cuckoldry for Seychelles warblers (Acrocephalus sechellensis) are considerable because warblers have a single-egg clutch and, given the short breeding season, no time for a successful replacement clutch. Neighbouring males are the primary threat to a male's genetic paternity. Males minimize their loss of paternity by guarding their mates to prevent them from having extra-pair copulations during their fertile period. Here, I provide experimental evidence that mate-guarding behaviour is energetically costly and that the expression of this trade-off is adjusted to paternity risk (local male density). Free-living males that were induced to reduce mate guarding spent significantly more time foraging and gained significantly better body condition than control males. The larger the reduction in mate guarding, the more pronounced was the increase in foraging and body condition (accounting for food availability). An experimental increase in paternity risk resulted in an increase in mate-guarding intensity and a decrease in foraging and body condition, and vice versa. This is examined using both cross-sectional and longitudinal data. This study on the Seychelles warbler offers experimental evidence that mate guarding is energetically costly and adjusted to paternity risk.     

The impact of paternity on male–infant association in a primate with low paternity certainty

In multimale groups where females mate promiscuously, male–infant associations have rarely been studied. However, recent studies have shown that males selectively support their offspring during agonistic conflicts with other juveniles and that father's presence accelerates offspring maturation. Furthermore, it was shown that males invest in unrelated infants to enhance future mating success with the infant's mother. Hence, infant care might provide fitness gain for males. Here, we investigate male–infant associations in rhesus macaques (Macaca mulatta), a primate with low paternity certainty as females mate with multiple partners and males ensure paternity less efficiently through mate‐guarding. We combined behavioural data with genetic paternity analyses of one cohort of the semi‐free‐ranging population of Cayo Santiago (Puerto Rico) and recorded affiliative and aggressive interactions between focal subjects and adult males from birth to sexual maturation (0–4 years) of focal subjects. Our results revealed that 9.6% of all interactions of focal subjects involved an adult male and 94% of all male–infant interactions were affiliative, indicating the rareness of male–infant aggression. Second and most interestingly, sires were more likely to affiliate with their offspring than nonsires with unrelated infants. This preference was independent of mother's proximity and emphasized during early infancy. Male–infant affiliation rose with infant age and was pronounced between adult males and male rather than female focal subjects. Overall, our results suggest that male–infant affiliation is also an important component in structuring primate societies and affiliation directed towards own offspring presumably represent low‐cost paternal care.     

Explicit experimental evidence for the role of mate guarding in minimizing loss of paternity in the Seychelles warbler

Extra-pair copulations (EPCs) (copulations outside the pair bond) resulting in extra-pair fertilizations (EPFs) are widespread in birds. To increase reproductive success, males should not only seek EPCs, but also prevent their females from having EPFs. Male Seychelles warblers (Acrocephalus sechellensis) follow their partner closely during the period when these females are most receptive (fertile period). The Seychelles warbler is the first species to offer explicit experimental evidence that mate guarding functions as paternity guarding: in territories where free-living males were induced to stop mate guarding during the pair female''s fertile period, the rates of intrusions by other males and successful EPCs (male mounting female) were significantly higher than those observed in the control group and in the absence of mate guarding the frequency of successful EPCs increased significantly with local male density. Male warblers do not assure their paternity through frequent copulations to devalue any sperm from other males: males do not copulate with their partners immediately following a successful EPC obtained by their partners, the frequency of successful within-pair copulations does not increase with the frequency of successful EPCs and females initiate all successful copulations and are capable of resisting copulation attempts.     

Mated pairs of owl monkeys (Aotus nancymaae) exhibit sex differences in response to unfamiliar male and female conspecifics

In socially monogamous species, mate‐guarding could be a reproductive strategy that benefits both males and females, especially when males contribute to parental care. By actively guarding mates, males may reduce their chances of being cuckolded, whereas females that mate‐guard may reduce the likelihood that their mates will desert them or acquire additional mates, and hence limit or reduce paternal care of offspring. Owl monkeys (Aotus spp.) are socially monogamous with biparental care of young and, hence, potential beneficiaries of mate‐guarding. We presented mated pairs of captive owl monkeys (A. nancymaae) with unfamiliar male and female conspecifics, to determine if either member of the pair exhibits intraspecific aggression toward an intruder or stays close to its mate, behaviors indicative of mate‐guarding. Male mates were more responsible for the maintenance of close proximity between mates than females. Male mates also exhibited elevated levels of behavior that signify arousal when presented with a male conspecific. These responses by mated male owl monkeys are consistent with patterns that may help prevent cuckoldry. Am. J. Primatol. 72:942–950, 2010. © 2010 Wiley‐Liss, Inc.     

Physiological Costs of Mate Guarding in the Japanese Beetle (Popillia japonica Newman)

Males of many insects directly defend their mates from rival males (i.e. mate guard) as a way to avoid sperm competition and thus increase their reproductive success. However, mate guarding may have associated costs for these males. We examined costs of mate guarding in Japanese beetles (Popillia japonica), a pest species which exhibits post‐copulatory mate guarding during which the guarding male cannot feed. In this species, food provides both energy and water for thermoregulation. Consequently, we focused on possible thermoregulatory and energetic costs of their mate guarding. In a field study, we found that guarding males had significantly higher thoracic temperatures than non‐guarding males, indicating a difference in their ability and/or need to thermoregulate. Paired males had significantly lower water levels than single males in the morning and evening, but not in the afternoon. In the laboratory, we found that mate‐guarding duration was significantly shorter at higher ambient temperature than at lower temperature, and males that had been starved guarded for less time than males that had not been starved. Our results suggest that because guarding males are unable to feed, they suffer energetic and thermoregulatory costs that appear to limit the amount of time that they can guard a female.     

The Conflict between Nest Guarding and Mate Guarding in Penduline Tits (Remiz pendulinus)

In penduline tits (Remiz pendulinus), polygynous males build several very elaborate nests successively during one breeding season to attract females. The time and effort invested in nest building is positively related to their mating success. Intraspecific competition for nest material resulting in nest material theft, delays males' nest building progress which in turn decreases their mating success. Therefore, a nest guarding strategy was predicted. In many bird species, males develop some kind of paternity strategy during the female fertile phase. However, as nest building and the female fertile phase frequently coincide, one would expect a trade-off between these strategies. In this study we determined in particular how nest guarding in males conflicts with their mate guarding behaviour in penduline tits. Our results show that nest building is costly in terms of a male's time budget. Thieves benefit by increasing their rate of acquiring nest material which reduces the effort invested in nest building. Nest guarding is an efficient strategy to avoid thieves, as indicated by the negative relation between the presence of the male near the nest and the frequency of nest material theft. Nest guarding is required for the whole building period but males, however, increased their mate guarding effort during the peak fertile phase to ensure their paternity. The data suggest that, for the trade-off “mate guarding versus nest guarding”, paternity insurance seems to be more important.     

Do male paternity guards ensure female fidelity in a duetting fairy-wren?

Most socially monogamous bird species engage in extra-pair mating,and consequently males may adopt various behavioral strategiesto guard paternity. However, the relationship between mate guardingand extra-pair paternity is unclear: low levels of extra-pairpaternity can be associated either with no mate guarding orwith intense mate guarding. We investigate paternity guardsin the purple-crowned fairy-wren (Malurus coronatus), a duettingspecies where extra-pair paternity is rare. This species isunusual in a genus known for extremely high levels of extra-pairmating. We examine the behavioral interactions between the sexesunderlying these low rates of extra-pair paternity and showthat male purple-crowned fairy-wrens do not use frequent copulationor courtship feeding to assure paternity or guard females acousticallyby duetting. Males maintain close proximity to females bothwhen they are fertile and when they are not breeding and donot invest in courtship displays to extra-pair females. Consistentwith predictions of theoretical models, low extra-pair paternityin this species may be related to female fidelity rather thanmale paternity assurance strategies, but short-term removalof males would be necessary to test this experimentally.     

Mate guarding, male attractiveness, and paternity under social monogamy

Socially monogamous species vary widely in the frequency ofextrapair offspring, but this is usually discussed assumingthat females are free to express mate choice. Using game-theorymodeling, we investigate the evolution of male mate guarding,and the relationship between paternity and mate-guarding intensity.We show that the relationship between evolutionarily stablemate-guarding behavior and the risk of cuckoldry can be complicatedand nonlinear. Because male fitness accumulates both throughpaternity at his own nest and through his paternity elsewhere,males evolve to guard little either if females are very faithfulor if they are very unfaithful. Attractive males are usuallyexpected to guard less than unattractive males, but within-pairpaternity may correlate either positively or negatively withthe number of extrapair offspring fertilized by a male. Negativecorrelations, whereby attractive males are cuckolded more, becomemore likely if the reason behind female extrapair behavior appliesto most females (e.g., fertility insurance) rather than thesubset mated to unattractive males (e.g., when females seek"good genes") and if mate guarding is efficient in controllingfemale behavior. We discuss the current state of empirical knowledgewith respect to these findings.     

Colour bands, mate choice and paternity in the bluethroat

Studies of several bird species have shown that coloured leg bands may affect a male's success in mate attraction and/or mating competition. From a colour band experiment in the field, we have previously reported that male bluethroats, Luscinia s. svecica, with blue and orange bands (BO males) guarded their mates less intensely at the peak of female fertility, and spent more time advertising for additional mates, than males banded with non-BO colours. These responses indicated that BO males experienced less threat to their paternity than did non-BO males, possibly mediated through an increased attractiveness. Here we present paternity analyses of the broods from the field study and test whether there were differences between the two male groups in within-pair or extrapair paternity. There were no significant differences between the two groups of males in paternity, suggesting effective male protection of paternity. However, extrapair paternity was infrequent in the 2 years of the field experiment; hence, the power in detecting effects on paternity does not allow a definitive conclusion on this issue. We also conducted an aviary experiment in which females were given the choice between a BO male and a non-BO male, to test whether females had preferences for particular colour bands. Females did not associate more with BO males, as would have been expected if these males were more attractive in social mate choice. Our results suggest that the effects of colour bands on social mate choice and paternity are, at best, weak. Copyright 2000 The Association for the Study of Animal Behaviour.     

Determinants of reproductive success across sequential episodes of sexual selection in a firefly

Because females often mate with multiple males, it is critical to expand our view of sexual selection to encompass pre-, peri- and post-copulatory episodes to understand how selection drives trait evolution. In Photinus fireflies, females preferentially respond to males based on their bioluminescent courtship signals, but previous work has shown that male paternity success is negatively correlated with flash attractiveness. Here, we experimentally manipulated both the attractiveness of the courtship signal visible to female Photinus greeni fireflies before mating and male nuptial gift size to determine how these traits might each influence mate acceptance and paternity share. We also measured pericopulatory behaviours to examine their influence on male reproductive success. Firefly males with larger spermatophores experienced dual benefits in terms of both higher mate acceptance and increased paternity share. We found no effect of courtship signal attractiveness or pericopulatory behaviour on male reproductive success. Taken together with previous results, this suggests a possible trade-off for males between producing an attractive courtship signal and investing in nuptial gifts. By integrating multiple episodes of sexual selection, this study extends our understanding of sexual selection in Photinus fireflies and provides insight into the evolution of male traits in other polyandrous species.     

Female mate choice and male–male competition in Tonkean macaques: Who decides?

The theory of sexual selection predicts that females should be discriminatory in the choice of sexual partners. Females can express their choice in two ways. In direct mate choice, they show preferences for certain partners. In indirect mate choice, they select partners by displaying sexually attractive traits, thus eliciting contest competition between males. We focused on a primate species in which females advertise the timing of their ovulation and studied the balance between these two choice strategies. We tested predictions related to three hypotheses about direct and indirect female choice, namely the best‐male, graded‐signal and weak‐selectivity hypotheses. We investigated the sexual and agonistic interactions occurring during oestrous periods in five captive groups of Tonkean macaques (Macaca tonkeana). The results showed that dominant males used mate guarding to monopolise sexual access to parous females that were in the fertile stage of their reproductive cycle, while lower‐ranking males monitored only nulliparous females. The distribution of sexual presentations indicated that females accepted different types of partners, supporting the weak‐selectivity hypothesis regarding direct mate choice. The analysis of behavioural sequences revealed that mate‐guarding males used mild coercive behaviours to prevent females from mating with other males at conception time. The distribution of mounts showed that females mainly mated with dominant males, which leads us to argue that the best‐male hypothesis provides the most parsimonious explanation regarding indirect mate choice in Tonkean macaques. At the individual level, it may be concluded that male competitive strategies prevented females from exercising direct mate choice. At the evolutionary level, however, female sexual advertising and thus indirect choice promoted competition between males. The outcome is that indirect mate choice appears more important than direct mate choice in female Tonkean macaques.