Male Brood Research Articles

Dietary effect of Cissus populnea and Securidaca longepedunculata aqueous leave extracts on reproductive, haematological and biochemical parameters of African catfish Clarias gariepinus (Burchell, 1822) broodstocks

The objectives of the present study were to evaluated gametes quality, haematological and biochemical parameters of the Clarias gariepinus brood stocks fed with varying concentrations of Cissus populnea (CP) and Securidaca longepedunculata (SL). Fish were fed with Diet 1 (control, 0 ml plant extract), Diet 2(0.5 ml/kg CP), Diet 3 (1.0 ml/kg CP), Diet 4 (0.5 ml/kg SL), Diet 5 (1.0 ml/kg SL) and Diet 6 ­ (0.5 ml/kg CP + 0.5 ml/kg SL) for 90 days. The results of haematocrit and red blood cell of treated groups were relatively similar to the control. The white blood cell and haemoglobin values were lower than the control group while the mean corpuscular volume, mean corpuscular haemoglobin were significantly difference across treatments however; an elevated glucose level was recorded in the treated groups. Also, the mean platelet volume and platelet distribution width were relatively similar across treatments. The serum testosterone, progesterone and estrogen were found to be higher in fish fed diet 2 (0.5ml/kg CP). C. populnea at 0.5 ml/kg significantly (p<0.05) improved eggs weight, fecundity, gonadosomatic index, % fertilization and hatchability. Male brood stocks fed diet 2 (0.5 ml/kg CP) recorded the highest values for sperm motility (56.67 ± 0.33%), milt count and volume (820.33 ± 0.33×10 6 /ml and 1.80 ± 0.05 ml respectively) across all groups. Similarly, fish fed diet 2 (0.5ml/kg CP) had the highest values for eggs weight (283.7±102.4g), fecundity (168,286 ± 57157), gonadosomatic index (32.59 ± 2.72), fertilization (62 ± 20.4%) and hatchability (62.92 ± 19.75%).The dietary supplementation of 0.5 ml/kg C. populnea extract highly enhanced the reproductive profiles of male and female C gariepinus brood stocks.

Biometric sexual and ontogenetic dimorphism on the marine catfish Genidens genidens (Siluriformes, Ariidae) in a tropical estuary

This paper aims to study the ontogenetic sexual dimorphism of Genidens genidens in Guanabara Bay, southeastern coast of Brazil. Altogether 378 specimens were anayzed (233 females and 145 males) with total length ranging from 13.3 to 43.5 cm. Specimens were measured for 12 body measurements, sex was identified and maturity stages were recorded and classified. Pearson’s linear correlation reveled a significant positive correlation between total length and all other body measures, except for base adipose fin, mouth depth and eye depth for immature females. Analyses nested PERMANOVA desing showed significant differences between maturity stages for each sex, between sexes considering or not maturity stages, indicating a variation in morphometric characteristics driven by sexual dimorphism. Differences among all maturity stages were also found, indicating an ontogenetic morphological difference. But immature individuals didn’t differ between sexes indicating that differentiation patterns starts with sexual development. The most important measures differing males and females were related to head characteristics, which appears to be key parameters to evaluate sexual differences. Due to male incubation of fertilized eggs and juvenile individuals &lt;59 mm in their oral cavity, head measures are proposed to be sex dimorphism not related to reproduction, but with post reproductive fase due to ecological and biological needs. [L1]Modificated as suggested by Reviewer E.

Development of short-snouted seahorse (Hippocampus hippocampus, L. 1758): osteological and morphological aspects

Information about early development after male release lags behind studies of juveniles and adult seahorses, and newborn seahorses, similar in shape to adults, are considered juveniles or fry. During early life, Hippocampus hippocampus present behavioural (shift in habitat, from planktonic to benthic) and morphological changes; for this reasons, the aims of this study are to define the stage of development of H. hippocampus after they are expelled from the male brood pouch and to establish direct or indirect development through an osteological analysis. The ossification process was studied in 120 individuals, from their release to 30days after birth. To analyse the osteological development, Alcian Blue-Alizarin Red double staining technique for bone and cartilage was adapted to this species. At birth, H. hippocampus presents a mainly cartilaginous structure that ossifies in approximately 1month. The bony armour composed of bony rings and plates develops in 10days. The caudal fin, a structure absent in juveniles and adult seahorses, is present at birth and progressively disappears with age. The absence of adult osteological structure in newborns, like coronet, bony rings and plates, head spines and components allowing tail prehensile abilities, suggests a metamorphosis before the juvenile stage. During the indirect development, the metamorphic stage started inside brood pouch and followed outside and leads up to reconsider the status of H. hippocampus newborns.

Paternity Outcomes in the Freshwater Gastropod, Chilina dombeiana in the Biobío River, Chile.

Studying the mating system of obligate aquatic organisms that inhabit river ecosystems is important for understanding its evolution as well as the role of biological and environmental factors in modulating population dynamics and species distributional patterns. Here, we studied the reproductive strategy of the Chilean endemic freshwater snail, Chilina dombeiana, in the Biobío River, one of the largest rivers in Chile. This species has a low potential for dispersal given the absence of a free-swimming larval stage (benthic larval development) and given that adults have a low capacity for mobility. We hypothesized that: 1. Females would mate with different males (polyandry) resulting in intrabrood multiple paternity, 2. Individuals from closer sites would be more related than individuals from distant sites, and 3. Male parental contributions would be unevenly distributed within broods. Individuals from three different sites were sampled along the river: upper, mid, and river mouth. In the laboratory, hatching juveniles from a total of 15 broods were collected for paternity analyses. We used microsatellite markers and the programs GERUD and COLONY to determine whether multiple paternity exists and to estimate the contribution of different males to the brood. We found that multiple paternity was very common at all of the sites analyzed with as many as 8 males fertilizing a single female and a mean of 4.2 fathers per brood estimated by COLONY. Sire contribution was skewed to particular males in several broods. In addition, overall relatedness among broods for the three sites ranged from 0.17 to 0.45 with evidence of many half-siblings. Relatedness differed among the three sites. Particularly in upstream sites or in anthropogenically disturbed populations, the high levels of multiple paternity observed in C. dombeiana may be an efficient strategy to avoid inbreeding and prevent the loss of genetic diversity within populations.

The effect of male incubation feeding on female nest attendance and reproductive performance in a socially monogamous bird

The incubation of eggs plays a key role in avian parental care. To ensure embryo development, incubating parents have to keep their eggs within the appropriate temperature limits. To do so, incubating individuals allocate substantial energy to the thermal demands of their eggs, but they face a trade-off with self-maintenance (own metabolism) because they usually cannot forage while incubating eggs. In species with female-only incubation, males can help their partners by providing them with food on the nest, a behavior which may enable females to spend more time incubating and could, consequently, lead to improved reproductive performance. In the study reported here, we first investigated whether incubation feeding by males affects nest attendance by females in Blue Tits (Cyanistes caeruleus) and subsequently determined how this incubation feeding affects reproductive performance. We found that the female nest attendance tended to increase with increasing amounts of food supplied by their male partner. Thus, males may enable females to incubate more when needed, as suggested by our observation that male incubation feeding was more frequent when the ambient temperature was lower, and especially so when females incubated later in the breeding season (during the study period the ambient temperature decreased rapidly over the breeding season, which is exceptional). Although female nest attendance did not result in a shorter time until the eggs hatched or in higher hatching success, females that attended the nest more produced heavier nestlings. We suggest that the trade-off between self-maintenance and meeting the demands of egg incubation likely tends to be less when females received more assistance from their partner during the egg incubation period, resulting in a higher investment in offspring.

On-board Breeding Trial of Hilsa (Tenualosa ilisha, Ham. 1822) and Testing of Larval Rearing in Bangladesh

The Hilsa shad, Tenualosa ilisha commonly known as Hilsa is one of the most commercially important fish species in South Asian countries. For the conservation of Hilsa it is necessary to establish a standard breeding and culture protocol along with the present Hilsa management activities. The on board breeding trial was conducted during 10 October 2016 to 02 November 2016 which was the peak breeding time of Hilsa for the year 2016. The male and female Hilsa broods were collected from the River Meghna using BFRI experimental net during afternoon and late evening of full moon and new moon time. A total of six breeding trials were conducted in which 13 pairs of selected Hilsa broods were used for the breeding trials. For the breeding trial, both eggs and milt were collected through stripping and then the eggs were mixed with the milt immediately. The fertilized eggs were transferred to a plastic hatching jar for incubation providing mild water circulation, aeration and shade to protect penetration of direct sunlight for controlling temperature i.e., to maintain congenial environment. During the incubation period, the eggs were observed for 24 hrs to study the embryonic and larval development stages of Hilsa. After 4.2-4.5 hrs of fertilization morula stage of embryonic development was identified and after 8-8.5 hrs. of fertilization 18-myotome stage of embryonic development was identified from the sixth breeding trial. After that, no embryonic development of egg was observed up to 12 hrs after fertilization and the fertilized eggs were found to be dead filled with fungus at the end. The water quality parameters were found in good range during the breeding trial though the temperature was found to be fluctuated from the optimum ranges needed for the incubation of fertilized eggs. Although it was not possible to be succeeded completely in artificial breeding of Hilsa, the experience of on board breeding trial in the major breeding ground of River Meghna will give the necessary insight for future works.

Demographic Analysis of a Declining Northern Bobwhite Population in Southwestern Ohio

Northern bobwhite (Colinus virginianus) populations continue to decline throughout much of their range, especially in the Midwestern United States. Land use and habitat changes are understood to be the primary cause of decline, and it is unclear how vital rates affect growth of regional populations. We estimated relative abundance and population vital rates of bobwhites on 8 private land sites in southwestern Ohio during 2008–2011. Life stage simulation analyses were used to model the influence of 9 demographic parameters on population growth rates (k). All but one vital rate, chick survival, were modeled with empirical data randomly selected from normal distributions estimated (mean 6 SD) from our study population. The median value of k after 1,000 simulations was 0.248 (inter- quartile range 1⁄4 0.113-0.428). Non-breeding season survival was the dominant vital rate, explaining 50.4% of variation in k, followed by nest success (r2 1⁄4 0.163), and breeding season survival of adults (r2 1⁄4 0.083). Chick survival, egg success, and clutch size individually explained in order 1.4 to 4.6% of variation in k when modeled with survival estimates. Renesting, double-brooding, and male incubation individually explained , 1% of the variation in k. Total fecundity modeled as the sum across individual vital rate components explained 36.9% of variation in k. Non-breeding season survival was the most limiting population vital rate, but age ratios of fall-captured birds and simulated fecundity values indicated partial limitation by recruitment. Population stability (k 1⁄4 1) could be achieved by increasing non-breeding survival from 10.9 to 36.9%. Higher rates of nest success, the second most limiting vital rate, would not stabilize population growth unless survival rates also increased. Bobwhite conservation strategies should emphasize habitat enhancements designed to increase survival rates and useable space during the non-breeding season in Ohio and possibly other Midwestern states.

Notes on the Breeding of the Purple-crowned Pigeon

This paper presents observations at eighteen nests of the Purple-crowned Pigeon near Kuranda, northern Queensland. The nest is described. The clutch size was one and the incubation period fourteen days. The male incubates and broods during the day and the female at night. Development of the chick is described. Breeding success was 25 per cent. The fledging period appeared to be a remarkably short six to eight days.

The seahorse genome and the evolution of its specialized morphology

Seahorses have a specialized morphology that includes a toothless tubular mouth, a body covered with bony plates, a male brood pouch, and the absence of caudal and pelvic fins. Here we report the sequencing and de novo assembly of the genome of the tiger tail seahorse, Hippocampus comes. Comparative genomic analysis identifies higher protein and nucleotide evolutionary rates in H. comes compared with other teleost fish genomes. We identified an astacin metalloprotease gene family that has undergone expansion and is highly expressed in the male brood pouch. We also find that the H. comes genome lacks enamel matrix protein-coding proline/glutamine-rich secretory calcium-binding phosphoprotein genes, which might have led to the loss of mineralized teeth. tbx4, a regulator of hindlimb development, is also not found in H. comes genome. Knockout of tbx4 in zebrafish showed a ‘pelvic fin-loss’ phenotype similar to that of seahorses.Supplementary informationThe online version of this article (doi:10.1038/nature20595) contains supplementary material, which is available to authorized users.

The genome of the Gulf pipefish enables understanding of evolutionary innovations.

BackgroundEvolutionary origins of derived morphologies ultimately stem from changes in protein structure, gene regulation, and gene content. A well-assembled, annotated reference genome is a central resource for pursuing these molecular phenomena underlying phenotypic evolution. We explored the genome of the Gulf pipefish (Syngnathus scovelli), which belongs to family Syngnathidae (pipefishes, seahorses, and seadragons). These fishes have dramatically derived bodies and a remarkable novelty among vertebrates, the male brood pouch.ResultsWe produce a reference genome, condensed into chromosomes, for the Gulf pipefish. Gene losses and other changes have occurred in pipefish hox and dlx clusters and in the tbx and pitx gene families, candidate mechanisms for the evolution of syngnathid traits, including an elongated axis and the loss of ribs, pelvic fins, and teeth. We measure gene expression changes in pregnant versus non-pregnant brood pouch tissue and characterize the genomic organization of duplicated metalloprotease genes (patristacins) recruited into the function of this novel structure. Phylogenetic inference using ultraconserved sequences provides an alternative hypothesis for the relationship between orders Syngnathiformes and Scombriformes. Comparisons of chromosome structure among percomorphs show that chromosome number in a pipefish ancestor became reduced via chromosomal fusions.ConclusionsThe collected findings from this first syngnathid reference genome open a window into the genomic underpinnings of highly derived morphologies, demonstrating that de novo production of high quality and useful reference genomes is within reach of even small research groups.Electronic supplementary materialThe online version of this article (doi:10.1186/s13059-016-1126-6) contains supplementary material, which is available to authorized users.

Molecular phylogeny and patterns of diversification in syngnathid fishes

The family Syngnathidae is a large and diverse clade of morphologically unique bony fishes, with 57 genera and 300 described species of seahorses, pipefishes, pipehorses, and seadragons. They primarily inhabit shallow coastal waters in temperate and tropical oceans, and are characterized by a fused jaw, male brooding, and extraordinary crypsis. Phylogenetic relationships within the Syngnathidae remain poorly resolved due to lack of generic taxon sampling, few diagnostic morphological characters, and limited molecular data. The phylogenetic placement of the threatened, commercially exploited seahorses remains a topic of intense interest, with conflicting topologies based on morphology and predominantly mitochondrial genetic data. In this study, we integrate eight nuclear and mitochondrial markers and 17 morphological characters to investigate the phylogenetic structure of the family Syngnathidae at the generic level. We include 91 syngnathid species representing 48 of the 57 recognized genera, all major ocean basins, and a broad array of temperate and tropical habitats including rocky and coral reefs, sand and silt, mangroves, seagrass beds, estuaries, and rivers. Maximum likelihood and Bayesian analyses of 5160bp from eight loci produced high congruence among alternate topologies, defining well-supported and sometimes novel clades. We present a hypothesis that confirms a deep phylogenetic split between lineages with trunk- or tail-brood pouch placement, and provides significant new insights into the morphological evolution and biogeography of this highly derived fish clade. Based on the fundamental division between lineages - the tail brooding “Urophori” and the trunk brooding “Gastrophori” - we propose a revision of Syngnathidae classification into only two subfamilies: the Nerophinae and the Syngnathinae. We find support for distinct principal clades within the trunk-brooders and tail-brooders, the latter of which include seahorses, seadragons, independent lineages of pipehorses, and clades that originated in southern Australia and the Western Atlantic. We suggest the seahorse genus Hippocampus is of Indo-Pacific origin and its sister clade is an unexpected grouping of several morphologically disparate Indo-Pacific genera, including the Pacific pygmy pipehorses. Taxonomic revision is required for multiple genera, particularly to reflect deep evolutionary splits in nominal lineages from the Atlantic versus the Indo-Pacific.

Courtship Calls in Blue TitsCyanistes caeruleus: Daily and Seasonal Occurrence and Link to Paternity

Many bird species use specific vocalizations in the context of courtship or (attempted) copulations. These vocalizations can be used to gain information about the courtship behaviour of individuals, even when courtship or copulation behaviour itself is difficult to observe. We recorded courtship vocalizations of Blue Tits Cyanistes caeruleus during three breeding seasons. In 2014, we recorded courtship calls at 14 locations spread out over a 40 ha forest containing a nestbox-breeding population of Blue Tits. Courtship calls occurred throughout the breeding season, but were most common in the period just before and during egg-laying. The rate of courtship calling showed a clear daily peak around dawn. In 2012 and 2013, we recorded courtship calls during the fertile period of the male's social mate. We monitored the presence of the female inside the nestbox and describe the occurrence of courtship calls that are apparently not directed to the social mate. The rate of these potential extrapair courtships correlated positively with a male's extra-pair paternity gain in 2012, but not in 2013. Extra-pair courtship call rate did not relate to paternity loss in the male's own brood.

The effect of ambient temperature, habitat quality and individual age on incubation behaviour and incubation feeding in a socially monogamous songbird.

Incubation is an important aspect of avian life history. The behaviour is energetically costly, and investment in incubation strategies within species, like female nest attentiveness and the feeding by the non-incubating partner during incubation, can therefore vary depending on environmental and individual characteristics. However, little is known about the combined effect of these characteristics. We investigated the importance of ambient temperature, habitat quality, and bird age on female incubation behaviour and male feeding of the incubating female (incubation feeding) in blue tits Cyanistes caeruleus, a socially monogamous songbird. An increase in ambient temperature resulted in a higher nest temperature, and this enabled females to increase the time off the nest for self-maintenance activities. Probably as a consequence of this, an increase in ambient temperature was associated with fewer incubation feedings by the male. Moreover, in areas with more food available (more deciduous trees), females had shorter incubation recesses and males fed females less often. Additionally, males fed young females more, presumably to increase such females’ investment in their eggs, which were colder on average (despite the length of recesses and female nest attentiveness being independent of female age). Male age did not affect incubation feeding rate. In conclusion, the patterns of incubation behaviour were related to both environmental and individual characteristics, and male incubation feeding was adjusted to females’ need for food according these characteristics, which can facilitate new insights to the study of avian incubation energetics.Significance statementParents often invest a substantial amount of energy in raising offspring. How much they do so depends on several environmental factors and on the extent they cooperate to raise the offspring. In birds, males can feed incubating females, which may allow females to stay longer on the nest, which, in turn, may ultimately improve reproductive success. The interplay between environmental factors and such incubation feeding on incubation attendance has, however, received little attention. Here, we show that favourable circumstances (higher ambient temperature and food availability) allowed incubating blue tit females to increase the time off the nest to improve self-maintenance and males to feed them less, whereas males also fed inexperienced partners more often. Thus, we show a concerted effect of several environmental and intrinsic factors on parental effort during incubation, which will help to improve the general understanding of avian incubation and parental care.

Comparative study of haematological, serum electrolyte and nonelectrolyte parameters of male and female Persian sturgeon (Acipenser persicus) brood stocks

Sturgeons are the most important principal market species in the Caspian Sea. In the present study, measurement of blood parameters was carried out with the aim of evaluating the normal value of hematological and serum biochemical parameters of brood stocks Acipenser persicus during spawning season. Blood samples were collected from 36 brood stocks of A. persicus (18 males and 18 females) during the spawning season. Higher value of red blood cells, white blood cells, haemoglobin, haematocrit was observed in male breeders with significant differences between female breeders (p>0.05). Haemoglobin and haematocrit value in this study was within the range of 8.70 to 9.2 g/dL and 29.73% to 30.26%, respectively. The statistically significant differences between mean corpuscular volumes, mean corpuscular haemoglobin, lymphocyte and neutrophil percentages, aspartate aminotransferase, alkaline phosphatase and creatine kinase were observed in the male and female brood stocks. It is concluded from this study, some of the hematological and serum biochemical parameters of male and female A. persicus breeders were significantly varied from each other. In comparative investigation with earlier reports, the values of red blood cells, haemoglobin and haematocrit are highly varied due to age variations of fish. However, further studies are necessary to understand the impact of sexual, age, size, length, and season and habitat variation. Serum biochemical parameters can be used for confirming the maturity of A. persicus and monitoring any changes in the water quality parameters and soil.

Spatiotemporal Spawning Patterns of Smallmouth Bass at Its Upstream Invasion Edge

AbstractClimate change and land‐use practices are causing widespread warming of streams, forcing resident species to adapt or migrate. For instance, in the John Day River, Oregon (Columbia River basin), rising temperatures are facilitating the range expansion of Smallmouth Bass Micropterus dolomieu into critical salmon rearing habitat. Understanding Smallmouth Bass reproductive ecology at its range boundaries is integral to understanding and ultimately predicting its upstream range expansion. We addressed this knowledge gap by exploring potential temperature‐mediated effects on Smallmouth Bass reproduction at the leading edge of its nonnative riverine distribution in the Pacific Northwest. We used continuous snorkel surveys to characterize its upstream extent in the North Fork John Day River, where we observed spawning patterns and measured adult nest‐guarding male size, fecundity, brood development, habitat attributes, and nest success over 2 years (2014, 2015). We found a pattern of asynchronous and protracted spawn timing across the leading invasion edge, &gt;90% nest success, and few changes in reproductive attributes (e.g., fecundity, brood development) as the thermal regime became increasingly colder. We also found increased selectivity of nest substrata and decreased guarding requirements in upstream habitats. These results suggest that reproductive success does not limit the upstream range expansion of Smallmouth Bass and highlight potential ecological benefits that may offset the energetic demands associated with dispersing upstream. Overall, our findings enhance the current understanding of how reproduction influences range expansion of nonnative Smallmouth Bass populations in streams, enabling us to better guide managers tasked with minimizing the spread of this nonnative species in the future.Received November 2, 2015; accepted February 1, 2016 Published online June 15, 2016

Costs and Benefits to Pregnant Male Pipefish Caring for Broods of Different Sizes.

Trade-offs between brood size and offspring size, offspring survival, parental condition or parental survival are classic assumptions in life history biology. A reduction in brood size may lessen these costs of care, but offspring mortality can also result in an energetic gain, if parents are able to utilize the nutrients from the demised young. Males of the broad-nosed pipefish (Syngnathus typhle) care for the offspring by brooding embryos in a brood pouch. Brooding males can absorb nutrients that emanate from embryos, and there is often a reduction in offspring number over the brooding period. In this study, using two experimentally determined brood sizes (partially and fully filled brood pouches), we found that full broods resulted in larger number of developing offspring, despite significantly higher absolute and relative embryo mortality, compared to partial broods. Male survival was also affected by brood size, with males caring for full broods having poorer survival, an effect that together with the reduced embryo survival was found to negate the benefit of large broods. We found that embryo mortality was lower when the brooding males were in good initial condition, that embryos in broods with low embryo mortality weighed more, and surprisingly, that males in higher initial condition had embryos of lower weight. Brood size, however, did not affect embryo weight. Male final condition, but not initial condition, correlated with higher male survival. Taken together, our results show costs and benefits of caring for large brood sizes, where the numerical benefits come with costs in terms of both embryo survival and survival of the brooding father, effects that are often mediated via male condition.

Observations on a breeding pair of Black Falcons Falco subniger in southern Victoria

Successful breeding activity is described for a pair of Black Falcons Falco subniger in southern Victoria&nbsp;(south of 37&deg;S) in 2014 and 2015 (brood of two fledglings in each year), among the few confirmed or recent such records&nbsp;for the region (agricultural land and remnant woodland west of Melbourne). Courtship (supplementary) feeding at the&nbsp;nest, male brooding of downy chicks, growth and development of chicks, and other novel aspects of breeding behaviour&nbsp;and vocalisations are described. One nestling period lasted 40 days, and the post-fledging period at least a month. Prey&nbsp;included birds and small mammals. The fledglings and adults appeared vulnerable to vehicle- and train-strike; a roadkilled&nbsp;specimen is described for the district. The breeding adults were cryptic, suggesting the need for further survey for&nbsp;nests in the region. They were also wary and susceptible to disturbance, indicating a need for caution when approaching&nbsp;and observing active nests at all stages of the breeding cycle.

Chronically time-in or intermittently time-out? Differentiating time-out from a shortage of opportunities

Males that provide parental care may lose opportunities to acquire extrapair mates or secondary social mates. These opportunity costs can be estimated as the product of (1) the degree to which a male's participation in care makes him unready for mating (i.e. represents ‘time-out’ from the mating pool) and (2) the availability of potential mating partners. One stage of parenting may therefore be more costly than another because it depresses a male's probability of capitalizing on any given mating opportunity, and/or because it occurs when alternative mating opportunities are more abundant. To determine whether male parental care limits extrapair mating in house sparrows, Passer domesticus, we tracked changes in male extrapair mating success across stages of their nesting cycles. We then assessed whether periods of reduced extrapair mating by males coincided with a scarcity of fertilizable females, or whether certain activities placed males in time-out. We found that the number of potential extrapair mates was significantly higher on days when a male's social mate was fertile than during incubation or nestling provisioning; breeding synchrony consequently reduces the realized opportunity costs of male parenting. Nevertheless, males with nestlings to feed suffered greater opportunity costs than might be expected because of their relative inefficiency at obtaining extrapair matings with potentially available females. During the incubation stage, by contrast, the males' probability of extrapair mating per fertile female averaged four times higher. Thus, nestling provisioning apparently places males in a partial time-out, but male incubation does not. Males may be more fully engaged in the extrapair mating pool during incubation because they typically devote little time to this form of care and, when confronted with an increase in the abundance of extrapair mating prospects, they reduce the time they commit to incubation.

Increased extra-pair paternity in broods of aging males and enhanced recruitment of extra-pair young in a migratory bird.

Despite keen interest in extra-pair mating in birds, its adaptive significance remains unresolved. Here, we use a multi-year dataset to test whether traits of a female's social mate influence her propensity to produce extra-pair offspring in a population of house wrens, and whether producing extra-pair young has consequences for a female's fitness through effects on offspring survival. Females were most likely to produce extra-pair offspring when paired with old males and when paired with males on poor-quality territories, although this latter effect was marginally nonsignificant. Among offspring, the cutaneous immunity of within-pair young decreased as the age of their sires increased, but cutaneous immunity of extra-pair young was not affected by the age of their extra-pair sires or by the age of the males rearing them. Extra-pair offspring were more likely than within-pair offspring to return as breeding adults to the local population, with extra-pair sons being more likely to return as a breeder for multiple years. Our findings support the hypothesis that females produce extra-pair offspring to enhance their inclusive fitness beyond what they are capable of given the male with which they are socially paired.

Male brood provisioning rates provide evidence for inter‐age competition for mates in female Cooper's Hawks Accipiter cooperii

Life history theory predicts that individuals should maximize lifetime reproductive success (LRS) by breeding as soon as they reach sexual maturity, yet many species delay breeding, either because there are insufficient available mates or breeding sites, or because delayed breeding yields higher LRS. Accipitriform species, such as Cooper's Hawk Accipiter cooperii, exhibit both delayed breeding and delayed plumage maturation. However, in certain circumstances, first‐year females in non‐definitive plumage do breed and apparently compete with older females for high‐quality breeding territories. We predicted that these young females are at a competitive disadvantage compared with older females and that older females would have both higher reproductive success and be able to acquire higher quality nesting territories. We conducted brood counts and measured prey delivery rates by male Cooper's Hawks in an expanding urban population located in Albuquerque, New Mexico (USA), to assess our prediction. We found that older females had higher reproductive success, fledging 1.6 more offspring than younger females, and that they occupied territories where males provisioned at higher rates of 0.37 more prey items per 2‐h period. Our results showed that older females fared better than first‐year females but it is unclear if this is the result of passive or active competition. Older females initiated nesting 14.3 days sooner than first‐year females and thus may have filled vacant, high‐quality territories before first‐year females began seeking mates. Additionally, first‐year females were never observed persistently to confront older females for breeding territories, but they did actively compete against each other. First‐year females may defer to older females who, in a direct competitive interaction, would be most likely to prevail. Thus, delayed plumage maturation in Cooper's Hawks may serve to focus competition for nesting territories within age classes.