Paternity analyses in wild‐caught and laboratory‐reared Caribbean cricket females reveal the influence of mating environment on post‐copulatory sexual selection

Polyandry is ubiquitous in insects and provides the conditions necessary for male‐ and female‐driven forms of post‐copulatory sexual selection to arise. Populations of Amphiacusta sanctaecrucis exhibit significant divergence in portions of the male genitalia that are inserted directly into the female reproductive tract, suggesting that males may exercise some post‐copulatory control over fertilization success. We examine the potential for male–male and male–female post‐copulatory interactions to influence paternity in wild‐caught females of A. sanctaecrucis and contrast our findings with those obtained from females reared in a high‐density laboratory environment. We find that female A. sanctaecrucis exercise control by mating multiple times (females mount males), but that male–male post‐copulatory interactions may influence paternity success. Moreover, post‐copulatory interactions that affect reproductive success of males are not independent of mating environment: clutches of wild‐caught females exhibit higher sire diversity and lower paternity skew than clutches of laboratory‐reared females. There was no strong evidence for last male precedence in either case. Most attempts at disentangling the contributions of male–male and male–female interactions towards post‐copulatory sexual selection have been undertaken in a laboratory setting and may not capture the full context in which they take place – such as the relationship between premating and post‐mating interactions. Our results reinforce the importance of designing studies that can capture the multifaceted nature of sexual selection for elucidating the role of post‐copulatory sexual selection in driving the evolution of male and female reproductive traits, especially when different components (e.g. precopulatory and post‐copulatory interactions) do not exert independent effects on reproductive outcomes.     

Costs of rearing and sex‐ratio variation in southern grey shrike Lanius meridionalis broods

Several non‐mutually exclusive hypotheses predict adaptive variation in the offspring sex ratio. When conditions for breeding are adverse, parents are predicted to produce more offspring of the less costly sex to rear (‘the cost‐of‐reproduction hypothesis’). Moreover, they also should produce the more dispersing sex in order to diminish future competition (‘the local‐resource‐competition hypothesis’). Here, we analyse brood sex ratio according to rearing conditions in the southern shrike Lanius meridionalis, a species with moderately reversed sexual dimorphism. Our results suggest that females are more costly to rear than males in this species. Adult females proved heavier than males, and female nestling tended to be heavier than male nestlings. Moreover, the greater brood reduction, the more male‐biased was the brood, suggesting that brood reduction implied higher mortality in female nestlings. Consistent with these findings, the brood sex ratio was biased to the less costly sex (males) when breeding conditions were adverse (bad years or low‐quality male parents), supporting the cost‐of‐reproduction hypothesis. By contrast, these findings did not support the local‐resource‐competition hypothesis, which predicted female‐biased brood sex ratio under adverse conditions. As a whole, our results support the idea that birds adaptively modulate sex ratio in order to minimize reproduction costs.     

Mate choice by wild and mass‐reared females of the Mediterranean fruit fly

The sterile insect technique (SIT) is used to control Mediterranean fruit fly, Ceratitis capitata (Wiedemann), but its effectiveness is limited by low sexual competitiveness of mass‐reared males. This study investigated whether wild and mass‐reared [from a temperature sensitive lethal (tsl) genetic sexing strain] females display similar mate preferences and thus exert similar selective forces on the evolution of male courtship behaviour. Wild females preferred wild males over tsl males, whereas tsl females mated indiscriminately. The probability that mounting resulted in copulation was related to the duration of pre‐mount courtship for wild females, and wild males performed longer courtships than tsl males. Copulation occurred independently of courtship duration in tsl females. Counter to the aim of the SIT, female choice by tsl females appears to promote the evolution of male behaviour disfavoured by wild females.     

Mortality costs of sexual selection and parental care in natural populations of birds

Abstract Is the cost of reproduction different between males and females? On the one hand, males typically compete intensely for mates, thus sexual selection theory predicts higher cost of reproduction for males in species with intense male‐male competition. On the other hand, care provisioning such as incubating the eggs and raising young may also be costly, thus parental care theory predicts higher mortality for the care‐giving sex, which is often the female. We tested both hypotheses of reproductive costs using phylogenetic comparative analyses of sex‐specific adult mortality rates of 194 bird species across 41 families. First, we show that evolutionary increases in male‐male competition were associated with male‐biased mortalities. This relationship is consistent between two measures of mating competition: social mating system and testis size. Second, as predicted by the parental cost hypothesis, females have significantly higher adult mortalities (mean ± SE, 0.364 ± 0.01) than males (0.328 ± 0.01). However, the mortality cost of parental care was only detectable in males, when the influence of mating competition was statistically controlled. Taken together, our results challenge the traditional explanation of female‐biased avian mortalities, because evolutionary changes in female care were unrelated to changes in mortality bias. The interspecific variation in avian mortality bias, as we show here, is driven by males, specifically via the costs of both mating competition and parental care. We also discuss alternative hypotheses for why most birds exhibit female‐biased mortalities, whereas in mammals male‐biased mortalities predominate.     

Growth and survivorship as proximate causes of sexual size dimorphism in peninsula dragon lizards Ctenophorus fionni

Males and females differ in body size in many animals, but the direction and extent of this sexual size dimorphism (SSD) varies widely. Males are larger than females in most lizards of the iguanian clade, which includes dragon lizards (Agamidae). I tested whether the male larger pattern of SSD in the peninsula dragon lizard, Ctenophorus fionni, is a result of sexual selection for large male size or relatively higher mortality among females. Data on growth and survivorship were collected from wild lizards during 1991–1994. The likelihood of differential predation between males and females was assessed by exposing pairs of male and female lizards to a predator in captivity, and by comparing the frequency of tail damage in wild‐caught males and females. Male and female C. fionni grew at the same rate, but males grew for longer than females and reached a larger asymptotic size (87 mm vs. 78 mm). Large males were under‐represented in the population because they suffered higher mortality than females. Predation may account for some of this male‐biased mortality. The male‐biased SSD in C. fionni resulted from differences in growth pattern between the sexes. The male‐biased SSD was not the result of proximate factors reducing female body size. Indeed SSD in this species remained male‐biased despite high mortality among large males. SSD in C. fionni is consistent with the ultimate explanation of sexual selection for large body size in males.     

Changes in behaviour associated with pair formation in the polychaete Harmothoë imbricata (L.)

Spacing between individuals in populations of Harmothoë imbricata has been investigated both on the shore and in the laboratory. Males tend to occur closer together than females, and the mean male‐male individual distance measured was less than the mean distance between females; male—female distances for immature worms were intermediate. When worms mature they pair: the male mounts the female and lies across her dorsal surface. There is evidence that after spawning the members of a pair separate. Contact responses between worms have been investigated in the laboratory. Most encounters between immature worms lead to separation, as a result of one or both worms moving rapidly away from the other or fighting; females show more marked avoidance behaviour than males. The majority of male‐male and female‐female encounters between mature worms also lead to separation but in male‐female encounters the male usually mounts the female. A male which has mounted a female becomes highly aggressive and will attack intruding males but not females.     

Stronger condition dependence in female size explains altitudinal variation in sexual size dimorphism of a Tibetan frog

The present study investigated altitudinal variation in sexual size dimorphism of a Tibetan frog Nanorana parkeri. Size dimorphism was female‐biased in all populations, although this bias became less at higher altitudes because of a steeper altitudinal decrease in female size than male size. Operational sex ratios, an indicator of the opportunity for sexual selection on larger males, changed independently of altitude. Clutch volume, an indicator of the strength of fecundity selection on larger females, was positively with female size, and tended to decrease approaching high altitudes. Females lived longer and grew more slowly than males, and the mean age in both sexes increased and growth rate decreased altitudinally, although the changes were more rapid in females than males. These results suggest that, relative to males, females (i.e. the sex that typically bears greater reproductive costs and experiences stronger directional selection for larger size to take fecundity advantages) should be more sensitive to environments, attaining a larger size via enhancing growth under favourable lower‐latitude conditions but a smaller size as a result of retarding growth when conditions become harsher at higher altitudes. This supports the condition‐dependence hypothesis with respect to intraspecific variation in sexual size dimorphism. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 107 , 558–565.     

Reciprocal grafting separates the roles of the root and shoot in sex‐related drought responses in Populus cathayana males and females

Drought stress responses and sensitivity of dioecious plants, such as Populus cathayana Rehd., are determined by different mechanisms in each sex. In general, males tend to be more resistant while females are more sensitive. Here, we used reciprocal grafting between males and females to determine the relative importance of roots and shoots when plants are exposed to drought stress. Total dry matter accumulation (DMA), photosynthetic capacity, long‐term water‐use efficiency (Δ), water potential and ultrastructure of mesophyll cells were evaluated to determine the different roles of root and shoot in sex‐related drought responses. Plants with male roots were found to be more resistant and less sensitive to water stress than those with female roots under drought conditions. On the contrary, plants with female shoots grew better than those with male shoots under well‐watered conditions. These results indicated that the sensitivity of males and females to water stress is primarily influenced by root processes, while under well‐watered conditions sexual differences in growth are primarily driven by shoot processes. Furthermore, grafting female shoot scion onto male rootstock was proved to be an effective mean to improve resistance to water stress in P. cathayana females.     

Independence of Sexual and Anti-Predator Perceptual Functions in an Acoustic Moth: Implications for the Receiver Bias Mechanism in Signal Evolution

The receiver bias model for the evolution of mating signals proposes that selection favors male displays that happen to stimulate a general, ancestral perception in females such that receptivity and successful courtship increase. If these male signals do arise, however, the female perception will operate in two contexts, the original, typically non‐sexual, one and courtship. We may then ask whether these two functions represent the same or distinct traits, which may be under separate neural and genetic control. We studied this question in Achroia grisella, a pyralid moth species in which males attract females, with an ultrasonic mating song. Hearing in pyralid moths is widespread and originated in an anti‐predator context – the perception and avoidance of echolocating bats – and it is inferred that the male song found in A. grisella, and in several other pyralid species, arose subsequently via a receiver bias mechanism: Females perceiving male‐produced ultrasound and responding with anti‐predator behavior normally exhibited in the presence of bat echolocations may have inadvertently increased the likelihood of successful courtship. We measured hearing responses in both sexual and anti‐predator contexts in inbred lines developed from an A. grisella population. Significant inter‐line variance was observed for sensitivity thresholds for female response to male song and for both female and male responses to synthetic bat echolocation signals. Female responses to male song and to synthetic echolocations differed markedly in sensitivity, and the median sexual and anti‐predator responses in the various lines were not correlated. However, a higher level of similarity occurs between the female and male anti‐predator responses. Thus, genetic variance for sexual and anti‐predator responses appears to exist, and the two responses may represent independent traits. These results imply that when male signals originate via a receiver bias mechanism, female perception does not necessarily remain fixed in its ancestral state but has the potential for continued modification.     

Sexual Competition,Coercive Mating and Mate Assessment in the One‐Sided Livebearer,Jenynsia multidentata: Are They Predictive of Sexual Dimorphism?

We investigated the mechanisms of sexual selection operating on body size in the one‐sided livebearer (Jenynsia multidentata), a small fish characterized by male dwarfism. Mating in the one‐sided livebearer is coercive: males approach females from behind and try to thrust their copulatory organ at the female genital pore. Females counter males' mating attempts by either swimming away or attacking them. We tested the hypothesis that the components of sexual selection favouring small size in males (sexual coercion) were more effective than those favouring a large size (male competition and mate choice). When alone, small males had a significantly higher success in their mating attempts than large males. The proportion of successful attempts was also positively correlated with female size. When two males competed for the same female, the large male had a significant mating advantage over the small one. With a 1 : 1 sex ratio, the large‐male mating advantage vanished because each male tended to follow a different female. Large males, however, preferentially defended large females, thus compelling small males to engage with smaller, less fecund females. Males did not discriminate between gravid and non‐gravid females, but preferred mating with larger females. This preference disappeared when males were much smaller than the female, probably in relation to the risk for the male of being eaten or injured by the female. In a choice chamber, male‐deprived females that had their sperm storage depleted remained close to males and showed a preference for large individuals, a behaviour not observed in non‐deprived females. Nonetheless, when placed with males in the same aquarium, all females showed avoidance and aggression. Struggling may represent a way by which the female assesses the skill and endurance of males.     

Trade‐offs in female signal apparency to males offer alternative anti‐harassment strategies for colour polymorphic females

Colour polymorphisms are known to influence receiver behaviour, but how they affect a receiver's ability to detect and recognize individuals in nature is usually unknown. I hypothesized that polymorphic female damselflies represent an evolutionary stable strategy, maintained by trade‐offs between the relative apparency of morphs to male receivers. Using field experiments on Enallagma hageni and focal studies of E. hageni and Enallagma boreale, I tested for the first time the predictions that (i) green heteromorphs and blue andromorphs gain differential protection from sexual harassment via background crypsis and sexual mimicry, respectively, and (ii) female morphs behaviourally optimize their signal apparency to mate‐searching males. First, based on male reactions elicited by females, against a high‐contrast background, the two morphs did not differ in being detected by males, and once detected, they did not differ in being recognized (eliciting sexual reactions). However, on green ferns, heteromorphs were less likely to be detected (elicited only fly‐bys) than andromorphs, but once detected, the morphs did not differ in being recognized. In contrast, when perched on a dowel with two male signal distractors, andromorphs were detected less often, and once detected, they were recognized less often than heteromorphs. Second, in fields where females foraged, andromorphs perched higher on vegetation than heteromorphs and were more often in the vicinity of males. Neither harassment rates nor evasive behaviours differed between morphs. Males aggregated in high density near shore where solitary females were rare. Equilibrium frequencies of these and other colour morphs should reflect the relative ease with which receivers detect and recognize them in the context where they are encountered.     

Spermatophore and Sperm Allocation in Males of the Monandrous Butterfly Pararge aegeria: the Female’s Perspective

In insects, spermatophore production represents a non‐trivial cost to a male. Non‐virgin males have been shown to produce small spermatophores at subsequent matings. Particularly in monandrous species, it may be an issue to receive a sufficiently large spermatophore at the first and typically only mating. Females of the monandrous Speckled wood butterfly Pararge aegeria (L.) produce fewer offspring after mating with a non‐virgin male. After mating, females spend all their active time selecting oviposition sites and typically ignore other males. Here, we show that females did not discriminate between a virgin male and a recently mated male in our laboratory experiments. We demonstrate that the number of eupyrene sperm bundles relative to spermatophore mass differed with subsequent male matings. Males transferred a significantly smaller spermatophore after the first copulation, but the spermatophore mass did not decrease further with subsequent matings. However, the number of eupyrene sperm bundles decreased linearly. Therefore, there was proportionally more eupyrene sperm in the male’s second spermatophore compared with the first and the later spermatophores. Such a pattern has been shown in polyandrous species. Hence, it suggests that differences in sperm allocation strategy between polyandrous and monandrous butterflies may be quantitative rather than qualitative. There was also a tendency for females that had mated with a recently mated male to have higher propensity to remate than did females that had mated with a virgin male. We discuss the results relative to the mating system in P. aegeria, including female remating opportunities in the field and male mate‐locating behaviour.     

Effects of mating order and male size on embryo survival in a pipefish

In species that provide parental care, individuals should invest adaptively in their offspring in relation to the pre‐ and post‐zygotic care provided by their partners. In the broad‐nosed pipefish, Syngnathus typhle L., females transfer large, nutrient‐rich eggs into the male brood pouch during mating. The male broods and nourishes the embryos for several weeks before independent juveniles emerge at parturition. Given a choice, females clearly prefer large partners. Yet, females provide protein‐richer eggs when the same individual mates with a smaller than a larger male. In the present study, we allowed each female to mate with one small and one large male, in alternated order. We found a strong effect of female mating order, with larger clutches and higher embryo mortality in first‐ than second‐laid broods, which may suggest that eggs over‐ripen in the ovaries or reflect the negative effects of high embryo density in the brood pouch. In either case, this effect should put constraints on the possibility of a female being selective in mate choice. We also found that small and large males produced embryos of similar size and survival, consistent with the reproductive compensation hypothesis, suggesting that, in this species, larger males provide better nourishment to the embryos than smaller males. © 2014 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 639–645.     

Intersexual variation in the foraging ecology of sexually monochromatic Western Wood‐Pewees

ABSTRACT Investigators generally pool observations of males and females in studies of the foraging behavior of sexually monochromatic songbirds. However, such pooling can obscure possible intersexual differences. We compared the foraging behavior of male and female Western Wood‐Pewees (Contopus sordidulus), a sexually monochromatic species, in the Sierra Nevada Mountains of California during the breeding seasons of 2007 and 2008. We recorded 143 foraging observations (male N= 74, female N= 69). Overall, mean foraging rates of females (2.8 attacks/min) were higher (P < 0.001) than those of males (1.1 attacks/min). In addition, female foraging rates were significantly higher during incubation than during the nest building, nestling, and fledgling periods. When foraging, males perched higher above ground than females (means = 17.1 and 6.7 m, respectively). Differences between male and female Western Wood‐Pewees in foraging rates and perch heights suggest that males may spend more time on vigilance while females focus on foraging quickly during incubation and when feeding nestlings. Because metrics such as foraging attack rates are sometimes used as indicators of habitat quality and we found that rates can differ between the sexes and among nesting stages, investigators should consider the possibility of such differences when assessing habitat quality, especially for sexually monochromatic species of birds.     

Pair‐living in the Absence of Obligate Biparental Care in a Lizard: Trading‐off Sex and Food?

A pair‐living social organisation can typically be explained by obligate biparental care. We investigated pair‐living in the absence of biparental care in the Australian sleepy lizard, Tiliqua rugosa, which forms exceptionally strong pair bonds. We fitted 10 lizards, five male–female pairs, with Global Positioning System (GPS) recorders and continuously monitored social associations and separations between active pair partners, based on location records taken every 10 min over 3 mo. Males temporarily separated and reunited the pair more frequently than females, but females also contributed to the maintenance of the pair bond. These behavioural data were consistent with the hypothesis that females successfully coerce males into associations with one female. Lower frequencies of social association between pair partners once mating had finished support this interpretation. Males that are coerced into pair associations appear to experience higher costs of pair‐living than females, because males initiated temporary separations of the pair more frequently than females. Males showed higher movement activity and remained active later each day. This sex bias in activity may be an important mechanism to mitigate the higher costs of pair‐living for males. Costs for males might include within‐pair competition for food as females appear more competitive. Our study provides detailed empirical data on a lizard pair bond and provides important insights into pair‐living in the absence of biparental care.     

The complexity of mating decisions in stalk‐eyed flies

All too often, studies of sexual selection focus exclusively on the responses in one sex, on single traits, typically those that are exaggerated and strongly sexually dimorphic. They ignore a range of less obvious traits and behavior, in both sexes, involved in the interactions leading to mate choice. To remedy this imbalance, we analyze a textbook example of sexual selection in the stalk‐eyed fly (Diasemopsis meigenii). We studied several traits in a novel, insightful, and efficient experimental design, examining 2,400 male–female pairs in a “round‐robin” array, where each female was tested against multiple males and vice versa. In D. meigenii, females exhibit strong mate preference for males with highly exaggerated eyespan, and so we deliberately constrained variation in male eyespan to reveal the importance of other traits. Males performing more precopulatory behavior were more likely to attempt to mate with females and be accepted by them. However, behavior was not a necessary part of courtship, as it was absent from over almost half the interactions. Males with larger reproductive organs (testes and accessory glands) did not make more mating attempts, but there was a strong tendency for females to accept mating attempts from such males. How females detect differences in male reproductive organ size remains unclear. In addition, females with larger eyespan, an indicator of size and fecundity, attracted more mating attempts from males, but this trait did not alter female acceptance. Genetic variation among males had a strong influence on male mating attempts and female acceptance, both via the traits we studied and other unmeasured attributes. These findings demonstrate the importance of assaying multiple traits in males and females, rather than focusing solely on prominent and exaggerated sexually dimorphic traits. The approach allows a more complete understanding of the complex mating decisions made by both males and females.     

Epicuticular compounds and sexual recognition in the ball-roller scarab, Canthon cyanellus cyanellus

We analyzed the role of cuticular compounds in sexual recognition of the carrion ball‐roller scarab, Canthon cyanellus cyanellus (LeConte) (Coleoptera: Scarabaeidae). Males rolled food balls with freeze‐killed females on them as though the females were alive. Acceptance of female cadavers was low when they were washed with solvents and increased significantly when the solvent extract was reapplied to the cadavers. Acceptance of female cadavers by males was significantly higher than that of male cadavers by females. Male cadavers washed with solvent and impregnated with female cuticular compounds were accepted by males as though they were frozen or living females. Similarly, extracted female cadavers impregnated with male cuticular compounds were accepted by females. These results suggest that C. c. cyanellus males recognize females by their cuticular compounds, whereas females use a combination of cuticular compounds and other unknown cues to recognize males.     

Sex-biased aggression and male-only care at sea in Brünnich's Guillemots Uria lomvia and Razorbills Alca torda

In several groups in the order Charadriformes, biparental care is followed by a period of male‐only care. Several hypotheses attempting to explain extended male parental care in shorebirds do not fit the Alcini. In a previous study of Brünnich’s Guillemots Uria lomvia and Razorbills Alca torda, we did not find support for female‐biased parental effort at the breeding site that would lead to males being in better condition to care for chicks at sea. However, in both species, males spent more off‐duty time at the breeding site than females, suggesting greater involvement in the defence of egg or chick, breeding site and mate. We predicted that there would be a male bias in size and aggressive behaviour associated with parental roles. To test this, body size and aggression of attending male and female Brünnich’s Guillemots and Razorbills were measured during incubation and brooding on the Gannet Islands, Labrador. Parental aggression was measured using natural observations of all agonistic interactions and, in Razorbills only, in situ responses to presentations of a predator model. In both species, males were significantly larger than females in culmen and gape length. Guillemot males initiated agonistic interactions more frequently than females during incubation. In contrast, female Guillemots were subjected to aggression more frequently than males and as a result were involved in more fights. In addition, the few chicks that were seen to die were being attended by single females. During the brooding period, Razorbill males responded aggressively to intruders more frequently than females, made more aggressive responses than females, and responded aggressively more frequently and more intensely than females to a predator model. In both species there was a similar male bias in morphology and behaviour that is consistent with male parents being more capable of protecting their chick, a probable advantage to chick survival during the uniparental care phase of some Charadriformes.     

Gustatory adaptation affects sexual maturation in male German cockroaches,Blattella germanica

Adaptations to hazardous environmental factors are essential for survival, although they may be maladaptive in conditions where the hazard is absent. In German cockroach (Blattella germanica L.) populations, glucose aversion has evolved rapidly in response to glucose‐containing insecticidal baits, but little is known about the consequences of this behaviour in the absence of bait. In the present study, glucose‐averse (GA) and wild‐type (WT) male German cockroaches are restricted to a range of nutritionally defined diets containing either glucose or fructose as the sole carbohydrate source, and time to first expression of courtship is measured by stimulating the male antennae daily with isolated antennae from receptive, 6‐day‐old females. Glucose‐averse males that are restricted to glucose‐containing diets mature their courtship responses significantly later than GA males restricted to fructose‐containing diets, whereas there is no difference in maturation of courtship responses between GA males restricted to fructose‐containing diets and WT males restricted to diets containing either sugar type. Glucose‐averse males furthermore respond later to GA female antennae than to WT female antennae, all from 6‐day‐old females. This suggests that GA females are less sexually stimulating, and the results are also consistent with earlier findings showing that GA females contain less developed oocytes than WT females at this age. These findings demonstrate that an adaptive gustatory mutation conferring protection from a toxin may have comparatively detrimental effects under conditions where the toxin has vanished, both by delaying female sexual maturation and signalling and by delaying male sexual maturation and courtship under conditions where glucose is a major energy source.     

Male‐skewed adult sex ratio,survival, mating opportunity and annual productivity in the Snowy Plover Charadrius alexandrinus

Sex differences in adult mortality may be responsible for male‐skewed adult sex ratios and male‐skewed parental care in some birds. Because a surplus of breeding males has been reported in serially polyandrous populations of Snowy Plover Charadrius alexandrinus, we examined sex ratio, early‐season nesting opportunities, adult survival and annual reproductive success of a Snowy Plover population at Monterey Bay, California. We tested the hypotheses that male adult survival was greater than female survival and that a sex difference in adult survival led to a skewed adult sex ratio, different mating opportunities and different annual productivity between the sexes. Virtually all females left chicks from their first broods to the care of the male and re‐nested with a new mate. As a result, females had time to parent three successful nesting attempts during the lengthy breeding season, whereas males had time for only two successful attempts. Among years, the median population of nesting Plovers was 96 males and 84 females (median difference = 9), resulting in one extra male per eight pairs. The number of potential breeders without mates during the early nesting period each year was higher in males than in females. Adult male survival (0.734 ± 0.028 se) was higher than female survival (0.693 ± 0.030 se) in top‐ranked models. Annually, females parented more successful clutches and fledged more chicks than their first mates of the season. Our results suggest that in C. alexandrinus a sex difference in adult survival results in a male‐skewed sex ratio, which creates more nesting opportunities and greater annual productivity for females than for males.