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Nest care is an important parental contribution to offspring. In woodpeckers, males often have an equal or greater contribution to parental care, including nest sanitation. The Black-backed Woodpecker (Picoides arcticus) is a North American boreal woodpecker for which both parents are highly involved in parental care. By modifying their territory size in optimal and suboptimal habitat (e.g. burned vs unburned habitats), this species seems to have a large tolerance to variation in prey abundance at a landscape scale, and could provide a useful biological model to investigate the adaptability of parent care, particularly to relative contribution of each sex. We investigated sex- and habitat-specific parental care behaviour of Black-backed Woodpeckers at 9 nests by daily monitoring during the nestling period. Specifically, we examined two different aspects of parental care: 1) time spent at the nest, and 2) food delivery. We also compared relative contribution between sexes to nest sanitation. Despite our small sample sizes, our results show that males are more involved in nest sanitation and spend longer at the nest, and both sexes exhibit higher food delivery rates and spend less time at the nest in burned habitat. This latter result may suggest that greater effort is needed to provision Black-backed Woodpecker nestlings in unburned habitat compared to burned habitat. [ABSTRACT FROM AUTHOR]

The article discusses research concerning the mother-infant dorsal carrying behaviour of a sun-tailed monkey (Cercopithecus solatus) at a forest guenon in Gabon. It highlights the effect of the maternal investment at several months which reduce the risk of infant mortality. An overview on the methods used as well as results and discussion about the research, is also given.

Hormonal systems have long been thought to play an important role in stimulating the onset of parental behavior, a critical component of reproductive success in a variety of taxa. Elevations in the peptide hormone prolactin (PRL) have been repeatedly positively correlated with the onset and maintenance of parental care across vertebrate species. A causal role for PRL in parental care has been established in several mammalian species, but less evidence for a causal role of PRL and parental care exists in birds. The zebra finch, a socially monogamous, biparental songbird, is an exceptionally useful animal model to study parental care and other close social relationships. Both sexes share parental care equally, exhibit the same parental behaviors, and show a marked improvement in breeding success with experience. We hypothesize that PRL is critically involved in the expression of zebra finch parental care and predict that circulating PRL levels will increase with breeding experience. To begin testing this, we measured plasma PRL concentrations in 14 male–female zebra finch pairs ( N = 28) across two breeding cycles, using a repeated measures design. PRL was measured in the birds’ first, reproductively inexperienced, breeding cycle beginning at courtship and extending through chick fledging. PRL was measured again during the birds’ second, reproductively experienced, breeding cycle, beginning with egg laying until chick fledging. We found that plasma PRL is significantly elevated from non-breeding concentrations during late incubation and early post-hatch care and that this elevation is greater in the reproductively experienced cycle compared to the inexperienced cycle. Findings of this study will be used to inform hypotheses and predictions for future experimental manipulations of PRL during parental care. [ABSTRACT FROM AUTHOR]

Exploring the links between parental supply and nestling demands and between nestling demand and food supply is of central importance for understanding the evolution of parent-offspring communication. It has been suggested that optimal food supply by parents and begging effort of nestlings are context dependent, and we here test some predictions of this hypothesis. House sparrow ( Passer domesticus) nestlings were experimentally fed with a pharmacological appetitive stimulant (cyproheptadine) that increases nestling demands, and explore its effect on nestling growth (i.e. body mass and tarsus length), which can be considered as the net payoff of inflated and costly offspring demand. As assumed by the experimental protocol, nestlings with an exaggerated demand were preferentially fed by parents. In accordance with the hypothesis, net benefits in terms of growth were mainly detected in first breeding attempt of parents that successfully reared three broods. Because costs associated with parental feeding should be lower for first breeding attempts and for parents of higher phenotypic quality (those able to successfully rear three clutches), our results provide to our knowledge, the first experimental evidence supporting a dynamic role of costs of food supply affecting net payoff of offspring demands, which may help to understand the mechanisms allowing the evolutionary equilibrium between intensities of offspring begging and parental provisioning. Significance statement: Both feeding and begging for food are costly activities for offspring and parents respectively. Rewards of such behaviours in terms of food receiving and reproductive success should vary depending on ecological conditions (i.e. food availability for offspring and physical condition of parents). Here we pharmacologically exaggerated appetitive of house sparrows ( Passer domesticus) nestlings and explore its effect on parental behaviour and on nestling growth (i.e. body mass and tarsus length). The expected benefits were mainly detected for first breeding attempts and only in nests of adults that were able to rear two more broods, that is, when costs of feeding the offspring by adults are lower. Our results provide to our knowledge, the first experimental evidence supporting dynamic outcomes of offspring demands and parental provisioning, which is essential for understanding the evolution of parent-offspring communication. [ABSTRACT FROM AUTHOR]

Parental imprinting is a mammalian-specific form of epigenetic regulation in which one allele of a gene is silenced depending on its parental origin. Parentally imprinted genes have been shown to play a role in growth, metabolism, cancer, and behavior. Although the molecular mechanisms underlying parental imprinting have been largely elucidated, the selective advantage of silencing one allele remains unclear. The mutant phenotype of the imprinted gene, Pw1/Peg3, provides a key example to illustrate the hypothesis on a coadaptation between mother and offspring, in which Pw1/Peg3 is required for a set of essential maternal behaviors, such as nursing, nest building, and postnatal care. We have generated a novel Pw1/Peg3 mutant allele that targets the last exon for the PW1 protein that contains >90% of the coding sequence resulting in a loss of Pw1/Peg3 expression. In contrast to previous reports that have targeted upstream exons, we observe that maternal behavior and lactation are not disrupted upon loss of Pw1/Peg3. Both paternal and homozygous Pw1/Peg3 mutant females nurse and feed their pups properly and no differences are detected in either oxytocin neuron number or oxytocin plasma levels. In addition, suckling capacities are normal in mutant pups. Consistent with previous reports, we observe a reduction of postnatal growth. These results support a general role for Pw1/Peg3 in the regulation of body growth but not maternal care and lactation. [ABSTRACT FROM AUTHOR]

A few studies indicate that limited nesting stress (LNS) alters maternal behavior and the hypothalamic pituitary adrenal (HPA) axis of dams and offspring in male Sprague Dawley rats. In the present study, we evaluated the impact of LNS on maternal behavior in Wistar rats, and on the HPA axis, glycemia and in vivo intestinal permeability of male and female offspring. Intestinal permeability is known to be elevated during the first week postnatally and influenced by glucocorticoids. Dams and neonatal litters were subjected to LNS or normal nesting conditions (control) from days 2 to 10 postnatally. At day 10, blood was collected from pups for determination of glucose and plasma corticosterone by enzyme immunoassay and in vivo intestinal permeability by oral gavage of fluorescein isothiocyanate–dextran 4kDa. Dams exposed to LNS compared to control showed an increase in the percentage of time spent building a nest (118%), self-grooming (69%), and putting the pups back to the nest (167%). LNS male and female pups exhibited a reduction of body weight by 5% and 4%, adrenal weights/100g body weight by 17% and 18%, corticosterone plasma levels by 64% and 62% and blood glucose by 11% and 12% respectively compared to same sex control pups. In male LNS pups, intestinal permeability was increased by 2.7-fold while no change was observed in females compared to same sex control. There was no sex difference in any of the parameters in control pups except the body weight. These data indicate that Wistar dams subjected to LNS during the first postnatal week have an altered repertoire of maternal behaviors which affects the development of the HPA axis in both sexes and intestinal barrier function in male offspring. [ABSTRACT FROM AUTHOR]

Alloparental care - care for unrelated young - is rare in animals, and its ecological or evolutionary advantages or, alternative maladaptive nature, remain unclear. We investigate alloparental care in the socially monogamous cichlid fish Perissodus microlepis from Lake Tanganyika that exhibits bi-parental care. In a genetic parentage analysis, we discovered a surprisingly high percentage of alloparental care represented by brood mixing, extra-pair paternity and extra-pair maternity in all broods that we investigated. The percentage of nondescendant juveniles of other parents, i.e., brood mixing, ranged from 5% to 57% (mean = 28%). The distribution of genetic parentage also suggests that this socially monogamous species has, in fact, polygamous mating system. The prevalence of genetically mixed broods can be best explained by two, not mutually exclusive hypotheses on farming-out and fostering behaviors. In the majority of broods, the sizes of the parents' own (descendant) offspring were significantly larger than those of the adopted (nondescendant) juveniles, supporting the 'selfish shepherd effect' hypothesis, i.e., that foster parents preferentially accept unrelated 'smaller or not larger' young since this would tend to lower the predation risks for their own larger offspring. There was also a tendency for larger parents particularly mothers, more so than smaller parents, to care predominantly for their own offspring. Larger parents might be better at defending against cuckoldry and having foreign young dumped into their broods through farming-out behavior. This result might argue for maladaptive effects of allopatric care for the foster parents that only larger and possibly more experienced pairs can guard against. It needs to be determined why, apparently, the ability to recognize one's own young has not evolved in this species. [ABSTRACT FROM AUTHOR]

Introduction: Maternal obesity is associated with a range of pregnancy complications, including fetal growth restriction (FGR), whereby a fetus fails to reach its genetically determined growth. Placental insufficiency and reduced nutrient transport play a role in the onset of FGR. Objectives: Metabolomic profiling was used to reveal altered maternal and fetal metabolic pathways in a model of diet induced obesity during pregnancy, leading to reduced fetal growth. Methods: We examined the metabolome of maternal and fetal livers, and placenta following a high fat and salt intake. Sprague-Dawley rats were assigned to (a) control diet (CD; 1 % salt, 10 % kcal from fat), (b) high salt diet (SD; 4 % salt, 10 % kcal from fat), (c) high fat diet (HF; 1 % salt, 45 % kcal from fat) or (d) high-fat high-salt diet (HFSD; 4 % salt, 45 % kcal from fat) 21 days prior to pregnancy and during gestation. Metabolites from maternal and fetal livers, and placenta were identified using gas and liquid chromatography combined with mass spectrometry. Results: Maternal HF intake resulted in reduced fetal weight. Altered metabolite profiles were observed in the HF maternal and fetal liver, and placenta. Polyunsaturated fatty acid metabolism was significantly altered in maternal and fetal liver by maternal fat intake. Conclusion: Excess of linoleic and α-linoleic acid (essential fatty acids) may be detrimental during placentation and associated with a reduction in fetal weight. Additionally, maternal, placental and fetal response to increased fat consumption seems likely to involve palmitoleic acid utilization as an adaptive response during maternal obesity. [ABSTRACT FROM AUTHOR]

Understanding how sexual conflict influences male and female parental decisions is a long-standing problem in behavioral ecology. Until now, most research on sexual conflict over parental care has focused on behavioral mechanisms mediating the resolution of this conflict through negotiation between parents. Here, we review evidence suggesting that maternal effects that alter offspring phenotypes may provide females with a mechanism for manipulating male care. We show that empirical studies on the role of maternal androgens in birds with biparental care provide no support for female manipulation of male care. However, we argue that it would be premature to conclude that maternal androgens play no role in female manipulation of male care given methodological problems in previous work. We then identify a number of additional mechanisms by which females may manipulate male care, including egg components other than androgens, egg size, and egg coloration. We show that there is good evidence that egg coloration affects male care, suggesting that this mechanism warrants further research. We also highlight that current evidence is derived from studies using experimental design that target specific candidate mechanisms, such as maternal androgens. Given the multitude of candidate mechanisms, we discuss an alternative approach based on targeting ecologically relevant prenatal conditions, such as food availability, and monitoring subsequent effects on candidate mechanisms, offspring phenotypes, and male and female care. Finally, we argue that it is timely to extend this work beyond birds with biparental care to include other taxa and species with uniparental male care and cooperative breeding. [ABSTRACT FROM AUTHOR]

Parental care is a defining feature of animal breeding systems. We now know that both basic life-history characteristics and ecological factors influence the evolution of care. However, relatively little is known about how these factors interact to influence the origin and maintenance of care. Here, we expand upon previous work and explore the relationship between basic life-history characteristics (stage-specific rates of mortality and maturation) and the fitness benefits associated with the origin and the maintenance of parental care for two broad ecological scenarios: the scenario in which egg survival is density dependent and the case in which adult survival is density dependent. Our findings suggest that high offspring need is likely critical in driving the origin, but not the maintenance, of parental care regardless of whether density dependence acts on egg or adult survival. In general, parental care is more likely to result in greater fitness benefits when baseline adult mortality is low if 1) egg survival is density dependent or 2) adult mortality is density dependent and mutant density is relatively high. When density dependence acts on egg mortality, low rates of egg maturation and high egg densities are less likely to lead to strong fitness benefits of care. However, when density dependence acts on adult mortality, high levels of egg maturation and increasing adult densities are less likely to maintain care. Juvenile survival has relatively little, if any, effect on the origin and maintenance of egg-only care. More generally, our results suggest that the evolution of parental care will be influenced by an organism’s entire life history characteristics, the stage at which density dependence acts, and whether care is originating or being maintained. [ABSTRACT FROM AUTHOR]

Dairy animals are subjected to a number of potential stressors throughout their lives, including daily interactions with humans. The quality of these interactions may have direct consequences for the animal undergoing the experience, but if such events occur during gestation it may also affect the developing fetus. This study examined the effects of differential handling during mid-gestation in 40 twin-bearing Saanen × Toggenburg primiparous goats. Between days 80 and 115 of gestation (gestation = 150 days), goats were subjected to aversive (AVS, n = 13), gentle (GEN, n = 13) or minimal (M, n = 14) handling protocols for 10 minute periods twice daily. The control (M) group did not receive handling treatments and all goats received normal husbandry procedures outside treatment periods. Salivary cortisol measured during the treatment period was higher in AVS goats (mean cortisol (sem) in pg/μl: AVS: 176.7 (18.2), GEN: 119.6 (11.1), M: 126.5 (13.7); P = 0.007). Data collection was focussed on mother-offspring behaviors 2 h post-partum, placental morphology and colostrum quality. AVS goats were the only treatment group to suffer fetal loss (16% loss vs 0% in GEN and M, P = 0.05). Treatment also influenced placental morphology with a tendency for fewer cotyledons evident in placentae from the aversive treatment (AVS: 87.9 (7.8), GEN: 107.1 (7.9), M: 112.1 (9.3), P = 0.093), and significantly fewer medium sized cotyledons (AVS: 67.6 (7.8), GEN: 89.3 (6.4), M: 84.3 (5.4), P = 0.042). GEN goats displayed more grooming and nosing behaviors towards their young during the first 2 h post-partum (grooming: GEN: 89.3% (7.1), AVS: 72.6% (7.7), M: 63.4% (9.0), P = 0.045; nosing frequency: GEN: 58.8 (12.5), AVS: 28.6 (11.1), M: 34.7 (6.5), P = 0.021). There was an overall trend for kids from mothers experiencing the AVS treatment to take longer to stand, reach the udder and suck compared to kids from GEN and M treatment groups. Treatment significantly affected latency to perform play behavior, with kids from AVS goats taking on average 25 min longer to play for the first time than kids from GEN and M treatment groups (P < 0.001). The results show that handling during gestation affects placental morphology, fetal survival and post-partum maternal behaviors, and influences kid behavioral development. Such results have important animal welfare implications, demonstrating that negative handling of pregnant females results in poorer placental quality with potential for fetal loss. It also demonstrates the beneficial effects of positive handling on enhancement of maternal behaviors. [ABSTRACT FROM AUTHOR]

Cryptic genetic variation plays an important role in the emergence of disease and evolutionary responses to environmental change. Focusing on parental care behavior, we discuss three mechanisms by which behavior can affect the accumulation and release of cryptic genetic variation. We illustrate how these hypotheses might be tested with preliminary data from Onthophagus dung beetles, which provide indirect parental care by provisioning their offspring with dung and sheltering them underground. The environmental stress hypothesis states that parental care reduces selection intensity on novel mutations when increased parental care results in a less stressful offspring environment. A review of recent literature, coupled with an irradiation experiment in beetles, suggests this mechanism may operate in some situations, but depends on the types of mutations under consideration. The relaxed selection hypothesis states that genes expressed in low care environments should be under weakened selection because their phenotypic manifestations are exposed to selection less frequently, and thus are prone to mutation accumulation. If parental care is reduced, for instance due to population-wide environmental changes, such cryptic variation may exert phenotypic effects, becoming exposed to selection. There is substantial theory in support of this hypothesis, and comparisons between beetle populations that differ in parental care behavior further support this idea. Finally, the compensation hypothesis states that organisms with direct parental care may be able to respond to cues or signals from offspring and compensate for genetic variants. We highlight the extensive discussion of this hypothesis with respect to medical care and genetic load in humans and explore invertebrate systems that may constitute powerful models for further inquiry. In summary, several mechanisms exist by which care behavior may shape the accumulation and release of cryptic genetic variation, thereby affecting the potential emergence of diseases and the rate and direction of evolutionary responses to novel environments. [ABSTRACT FROM AUTHOR]

The immune system is an important defence against pathogens but requires resources that hosts may also use otherwise. Thus, trade-offs between investment in immunity versus other life-history traits may exist, especially during resource-demanding periods such as reproduction. Here, we investigated the potential trade-off between an activated immune system and parental care in free-living great tits. We also studied whether variation in baseline immune indices prior to immunization contributes to individual differences in the responses to an immune challenge. To this end, we injected free-living great tit females with either phosphate-buffered saline (PBS) or with bacterial lipopolysaccharides (LPS) when nestlings were 9 days old and subsequently recorded parental feeding rates. We quantified potential fitness consequences via the growth and survival of their nestlings. Exposure to LPS tended to decrease female feeding rates. However, nestling body mass was not affected by the maternal immune challenge, probably because males compensated for the change in feeding rate of their partner. We found a negative relationship between haptoglobin levels and female feeding rates pre-treatment, but not with any of the other innate immune traits. Although there was substantial variation in female innate immune indices, we found no evidence that baseline immunity affected how females reacted to an immune challenge in terms of changes in parental behaviour. [ABSTRACT FROM AUTHOR]

Parental care in long-lived bird species involves a trade-off between the benefits of increasing the effort expended on current offspring and the costs that this represents for future reproductive output. Under regimes of high environmental variability, long-lived seabirds can adjust their breeding effort to buffer the negative effects of this variability on their offspring. However, the potential impacts of variation in breeding effort on offspring physiology in the short term and on longer-term survival are poorly understood. In this study, we manipulated brood age through a cross-fostering experiment to assess whether increasing or decreasing parental reproductive expenditure led to costs in Blue-footed Booby Sula nebouxii chicks. Specifically, we tested the consequences of altered parental reproductive expenditure on the offspring's physiological condition (plasma metabolites, heterophil to lymphocyte ratio (H/L) and body condition index ( BCI)) and survival. Offspring from broods in which parental investment was experimentally increased showed a lower BCI and lower alkaline phosphatase levels and higher H/L ratios than controls. Conversely, offspring showed the opposite pattern when reproductive expenditure was experimentally decreased. We observed no effects of manipulation of parental investment on triglyceride levels or on survival rates. Although our findings suggest that Blue-footed Booby parents have the ability to adjust their breeding effort according to the demands of their offspring, parental effort could influence the effect of hatching order by suppressing the aggressive tendency of the senior chick. [ABSTRACT FROM AUTHOR]

Studies of avian nest success often focus on examining influences of variation in environmental and seasonal factors. However, in-depth evaluations can also incorporate variation in individual incubation behaviour to further advance our understanding of avian reproductive ecology. We examined these relationships in colonially nesting Black-crowned Night-Herons Nycticorax nycticorax using intensive video-monitoring methods to quantify incubation behaviours. We modelled nest survival as a function of both extrinsic factors and incubation behaviours over a 3-year period (2010-12) on Alcatraz Island, USA. Model-averaged parameter estimates indicated that nest survival increased as a function of greater incubation constancy (% of time spent incubating eggs within a 24-h period), and average daily precipitation throughout the nesting stage. Common Ravens Corvus corax are the only known nest predator of Night-Herons on Alcatraz Island, as on many other coastal Pacific islands. We also investigated the effects of heterospecific nesting of California Gulls Larus californicus and Western Gulls Larus occidentalis in a mixed-species colony with Night-Herons, based on nesting proximity data collected over a 2-year period (2011-12). This second analysis indicated that, in addition to incubation behaviours, nesting heterospecifics are an important factor for explaining variation in Night-Heron nest survival. However, contrary to our original expectation, we found that Night-Herons experienced increased nest survival with increasing distance from gull colony boundaries. These results may apply to other areas with multiple colonial nesting species and similar predator communities and climatic patterns. [ABSTRACT FROM AUTHOR]

We documented parental behaviour and paternity of eastern kingbirds (Tyrannus tyrannus) to test the predictions that paternal care would decline with increasing loss of paternity, increasing nesting density (a proxy for probability of paternity loss), male quality, and number of fertile females available in the population. Extra-pair young were found in 58% of 45 nests for which behaviour was recorded and a higher proportion of young were extra-pair as nesting density increased. Male feeding rate declined with increasing nesting density and male quality, but neither feeding rate nor a composite measure of paternal behaviour varied with number of fertile females or paternity. Although alternative explanations exist, one interpretation of the reduced paternal care at high nesting density was that it was a response to perceived threats of paternity loss. The ultimate basis for the lower paternal effort of higher quality males is unclear but we discuss several possible explanations. [ABSTRACT FROM AUTHOR]

The effects of parity and litter size on maternal behavior of Small Tail Han sheep was investigated at Linyi University, China. Sixty-eight ewes were observed from parturition to weaning. Continuous focal animal sampling was used to quantify the duration of maternal behaviors. Ewe feces were collected every 2 days and estradiol concentration was measured with an enzyme immunoassay kit. All lambs were weighed 24 h after parturition and again at 35 days of age. Parity increased sucking, following, grooming, low-pitched bleat, head-up and udder-refusal behavior and decreased aggressive behavior ( P < 0.01, P < 0.01, P < 0.05, P < 0.05, P < 0.05, P < 0.05, P < 0.01, respectively), and litter size showed significant effect on sucking, following and low-pitched bleat behavior ( P < 0.05, P < 0.01, P < 0.05, respectively). The lambs of multiparous ewes were significantly heavier than primiparous ewes at birth ( P < 0.01) and were significantly heavier at weaning age ( P < 0.01). Similar results were founded for birth weight and weaning weight gain in litter size ( P < 0.01, P < 0.01, respectively). Estradiol concentration in feces was higher in multiparous ewes than primiparous ewes. Parity and litter size may have effects on maternal behavior during lactation. Ewes that have 2-3 lambs may be more suitable for production of Small Tail Han sheep in China. [ABSTRACT FROM AUTHOR]

Parental care confers benefits to juveniles but is usually associated with substantial costs for parents. These costs often depend on parental condition, which is thus considered as a key determinant of the level of parental care expressed during family life. However, how parental condition affects the behaviors that juveniles express toward their siblings and parents remains poorly explored. Here, we investigated these questions in the European earwig Forficula auricularia, an insect in which mothers provide extensive forms of care to their juveniles. We measured maternal body condition at egg hatching, subsequently manipulated maternal nutritional state, and finally assessed both food transfer among siblings and the nature of mother-offspring interactions. We also considered variation in brood size, an important parameter in family interactions. We found that food transfer among siblings increased with brood size when the tending mothers were in a deteriorated nutritional state. This effect was masked when the nutritional state of mothers was enhanced. The frequency of care-related behaviors that juveniles expressed toward their mother was higher when she was in a deteriorated rather than an enhanced nutritional state, while it overall increased with brood size. Finally, increasing values of maternal body condition entailed a shift from a positive to a negative association between maternal care behaviors and brood size, but only when the mothers' nutritional state was deteriorated. Overall, our results demonstrate that parental condition and brood size do not only affect parental behaviors but can also be important and entangled drivers of offspring behaviors during family life. [ABSTRACT FROM AUTHOR]

It is generally assumed that there is sexual conflict over the mating system. In this view, polygyny benefits males at a cost to females, and it is hence unclear why females accept polygynous mating. However, in the facultatively polygynous fish, Neolamprologus pulcher, no costs of polygyny to females have thus far been detected. We hypothesized that the costs of polygyny remained undetected because they accrue over longer periods of time through reduced tenure and/or survival. We conducted an extended field study in which we monitored the behavior and survival of individuals breeding either monogamously or under polygynous conditions within the same natural colony. We expected that polygyny would reduce male and female survival through increased competition among males and reduced amounts of received paternal effort for females. Consequently, breeder tenure and pair stability were predicted to be lower in more polygynous groups. Our data indeed revealed costs of polygyny to both sexes. Polygynous males faced higher competition, and females paired to polygynous males received reduced paternal effort. However, this did not result in different survival rates between individuals breeding under monogamous or polygynous conditions. We conclude that in N. pulcher the fitness costs of polygyny may be either too marginal to be detected with the approaches used thus far, or that males and females in this species do not face a conflict of interest over the mating system. This raises the question which ecological factors may resolve sexual conflict, and how the accruing mating system feeds back on a species' ecology. [ABSTRACT FROM AUTHOR]

Caring for offspring is energetically expensive, and when the costs of care are sufficiently high, the use of cost-reducing strategies can be favored. Such strategies may include the avoidance of nest construction through nest take-over and the restoration of depleted energy reserves through offspring cannibalism. Despite extensive theoretical and empirical work on parental care, neither the actual energetic costs of care nor the putative benefits of cost-reducing strategies have been systematically measured. Using plainfin midshipman fish, Porichthys notatus, we assessed how energy reserves of caring parents varied with duration of care, offspring cannibalism, and nest take-overs. We show that liver glycogen and lipid contents declined by 58% and 18.7%, respectively, that liver investment (measured via a hepatosomatic index) declined by 32.6%, and that muscle protein content declined by 8.8%. Other measures of body condition and energy reserves, such as hepatic glucose and adenosine triphosphate, remained stable over the extraordinarily long care period (3 months). Experimentally starved fish showed depletions of energy stores similar to caring fish. Fish that took over nests or that cannibalized eggs both had higher glycogen reserves than fish that did not adopt these strategies. These findings show that even when parental care is energetically costly, starvation may not be the dominant driving factor behind parent-offspring cannibalism. [ABSTRACT FROM AUTHOR]

In species with biparental care, there is sexual conflict over parental investment because each parent benefits when their partner bears more of the reproductive costs. Such conflict can be costly for offspring, but recent theoretical work predicts that parents can resolve sexual conflict through behavioral negotiation, specifically by alternating their trips to provision nestlings. However, this idea has received almost no empirical attention. In this study, we test the hypothesis that parents alternate their delivery of food to offspring in long-tailed tits (Aegithalos caudatus) and investigate whether this coordination of parental care is associated with greater reproductive success. We show that parents alternate provisioning trips more than would be expected by chance and that parental alternation is repeatable across multiple observation periods at a nest. More alternation is associated with increased visit synchrony and increased food delivery to nestlings. Moreover, we found that nests with more alternation were less likely to be predated, probably resulting from reduced activity around the nest when parents coordinate their provisioning behavior. Our results support the hypothesis that alternation of offspring provisioning is a behavioral adaptation to reduce the costs of sexual conflict. [ABSTRACT FROM AUTHOR]

We present descriptions of nest architecture, clutch size, nestling growth and nestling attendance for the Fire-eyed Diucon ( Xolmis pyrope), based on nests found at the Fray Jorge National Park, Chile, at the northernmost part of its distribution. Nests were cup-shaped structures averaging 283.5 ± 26.6 mm in width and 123.1 ± 6.8 mm in height ( n = 5), found in matorral steppe habitat and Olivillo humid forest relicts. Nests contained 2-3 eggs. Nestling growth in Fray Jorge's nests was nearly two times slower than in populations from central Chile, as suggested by our calculations of the constant rate ( K = 0.277) and the T10-90 period (12.9). During 20 hrs of video recording, the breeding adults spent a total of 3.4 hrs at the nest. Both parents attended the nest, and the rates of visits, nestling provisioning and fecal sac removal increased with nestling development. We observed that adults can still care for the young at least 2 weeks after fledging, covering an area of 2.3 ha while searching for food. This information could be valuable for further studies on geographic variation in the species' behavioral ecology. [ABSTRACT FROM AUTHOR]

Among several types of parental care behavior, incubation behavior in passerine birds offers an ideal opportunity to study the link between female parental care and male ornamentation, because males generally lack an incubation patch, and thus rarely incubate. Although preceding studies have focused mainly on on-bout duration (or its total amount, i.e., nest attentiveness), it has recently been established that off-bout durations, independent of on-bout durations, are also important for embryo development and thus for efficient incubation. Using Barn Swallows Hirundo rustica, we found that the duration of female incubation off-bouts increased with a sexually selected trait, male throat coloration, independent of female nest attentiveness. A longer female off-bout was positively correlated with the incubation period, indicating that colorful males had reproductive disadvantage because of their mates' inefficient incubation. Together with a previous study in which females demonstrated a higher amount of incubation when their mates had large white tail spots, another sexually selected trait, our findings indicated that the different aspects of parental care are differently related to male ornaments. Multiple aspects of parental care should be considered when examining the reproductive (dis)advantage of male ornamentation during parental care. [ABSTRACT FROM AUTHOR]

Copepod mating is a complex behavioral interplay between males and females. But successful mating also requires a physiological component in terms of egg- and spermatophore production. In striking contrast to the extensive literature on copepod egg production, costs of spermatophore production has largely been ignored. This article explores the energetic demands in male copepod reproduction, testing how food and predation risk influence spermatophore production. Moreover, we analyse swimming behavior to test if predation risk and food act on reproductive investments via behavioral responses. We found that spermatophore production depends strongly on food availability. The copepods increased grazing rates with predation risk when food was limited, and video analyses revealed that males spend less time swimming in presence of a risk cue. A review of the few available spermatophore production rates suggests that food limits spermatophore production for copepods at large. Apparently, potential encounter rates with mates or predators did not influence spermatophore production. However, the reduced activity indicates a trade-off between risk avoidance and mate encounter, potentially influencing mating rates. This study shows that males invest considerable resources in each spermatophore, with implications for mating strategies and population dynamics in copepods, the most abundant metazoans on earth. [ABSTRACT FROM AUTHOR]

Background: Alcohol consumption during pregnancy and lactation induces detrimental consequences, that are not limited to the direct in utero effects of the drug on fetuses, but extend to maternal care. However, the occurrence and severity of alcohol toxicity are related to the drinking pattern and the time of exposure. The present study investigated in female rats long-term alcohol drinking trajectories, by a continuous and intermittent free-choice paradigm, during pre-gestational time, pregnancy, and lactation; moreover, the consequences of long-term alcohol consumption on the response to natural reward and maternal behavior were evaluated. Methods: Virgin female rats were exposed to home-cage two-bottle continuous- or intermittent "alcohol (20%v/v) vs. water" choice regimen along 12 weeks and throughout pregnancy and lactation. Animals were tested for saccharin preference, and maternal behavior was assessed by recording dams' undisturbed spontaneous home-cage behavior in the presence of their offspring. Results: Our results show that the intermittent alcohol drinking-pattern induced an escalation in alcohol intake during pre-gestational time and lactation more than the continuous access, while a reduction in alcohol consumption was observed during pregnancy, contrarily to the drinking trajectories of the continuous access-exposed rats. Long-term voluntary alcohol intake induced a decreased saccharin preference in virgin female rats and a significant reduction in maternal care, with respect to control dams, although the intermittent drinking produced a greater impairment than the continuous-access paradigm. Conclusion: The present data indicate that both alcohol-drinking patterns are associated to modifications in the drinking trajectories of female rats, in pre-gestational time, during pregnancy and lactation. Moreover, long-lasting alcohol intake can affect sensitivity to natural rewarding stimuli and maternal behavior and sensitivity to natural rewarding stimuli in a pattern--related manner. This study underlies the importance of modeling human alcohol habit and its consequences on the mother-infant dyad, in order to prevent detrimental effects on offspring development and maturation. [ABSTRACT FROM AUTHOR]

Background: Parental allocation and reproductive success are often strongly influenced by environmental factors. In this respect, salinity is a key factor influencing species distributions and community structure in aquatic animals. Nevertheless, the effects of salinity on reproductive behaviours are not well known. Here, we used the sand goby (Pomatoschistus minutus), a small fish inhabiting a range of different salinities, to experimentally assess the effects of changes in salinity on nesting behaviour, a key component of reproduction in sand gobies and many other taxa. Results: We found that salinity levels influenced some aspects of male nesting behaviour (i.e. nest entrance size) but not others (i.e. latency to build a nest, choice of nest site, sand on top of nest) and that small and large individuals were differently affected. In particular, the importance of body size in adjustment of nest entrance depended on the salinity level. Conclusion: The results support the prediction that geographically widespread aquatic species, such as sand gobies, are able to perform well under a range of salinity levels. The phenotype by environment interaction found between male size and behavioural responses to salinity can, in turn, help to explain the notable variation observed in nest-building (and other) behaviours closely linked to reproduction. [ABSTRACT FROM AUTHOR]

In species with biparental care, individuals adjust their workload to that of their partner to either compensate or match its investment. Communication within a pair might be crucial for achieving this adjustment. Zebra finches, Taeniopygia guttata, form life-long monogamous pair bonds, in which partners are highly coordinated and both incubate the eggs. When relieving each other during incubation, partners perform a structured call duet at the nest. If this duet functions to coordinate incubation workload, disrupting the pair's usual nest-relief pattern by delaying the male's return to the nest should affect the structure of the duet. Using domesticated birds breeding in a large aviary, we found that delaying the male's return induced shorter duets with higher call rates. In addition, we tracked the location of individuals with a transponder at the nest and the feeder, and showed that these accelerated duets were associated with an increased haste of the partners to take turns incubating and foraging. Females also spent less time incubating during their subsequent shift, and females' time off-nest was best predicted by their mate's calling behaviour in the previous duet. Taken together, these results suggest that duets may function as 'vocal negotiation' over parental care. [ABSTRACT FROM AUTHOR]

Parental care, a central component of reproduction in a wide range of animal species, often involves elaborate behavioural interactions between parents and their offspring. Due to the reciprocal nature of these interactions, it has been hypothesized that parental and offspring behaviours (e.g. parental food provisioning and offspring begging) are not only target but also agent of selection. These traits are therefore expected to co-evolve, ultimately leading to co-adaptation of parent and offspring behaviours within families. However, empirical data on such parent-offspring co-adaptation are limited, particularly for wild populations. Furthermore, mean levels of behaviour (as measured in previous studies) may not adequately describe the dynamic nature of the reciprocal interplay between parents and their offspring, and instead rather the behavioural reaction norms for provisioning and begging may be co-adapted., We applied a large-scale cross-fostering study over 3 consecutive breeding seasons to investigate whether provisioning behaviour of wild blue tit ( Cyanistes caeruleus) parents covaries with the begging behaviour of their genetic, cross-fostered offspring. We simultaneously analysed parent and offspring behaviours, both as static traits (mean levels) and behavioural reaction norms (offspring begging as a function of food deprivation and parental provisioning as a function of short-term experimental changes in brood size)., Neither maternal nor paternal provisioning rates covaried with the begging intensity of their genetic offspring when analysed as mean levels of behaviour. However, the slopes of the reaction norms for provisioning and begging were negatively correlated between male, but not female, parents and their genetic offspring. Thus, fathers that change their provisioning rate strongly with brood size sire offspring whose level of begging only weakly increases with hunger, and vice versa., The observed covariation suggests the existence of sex-specific optima for parent-offspring trait combinations. Thus, our study not only highlights the importance of a behavioural reaction norm approach when investigating parent-offspring interactions, but also stresses the relevance of considering parents as separate units, at least for biparental species. [ABSTRACT FROM AUTHOR]

This study investigated the effect of hydrological stress (streamflow reduction) on the reproductive and nesting behaviour of freshwater blenny ( Salaria fluviatilis) males in a Mediterranean-type stream in NE Spain (a tributary of the Ebro River). The investigation included two study periods: (i) before stream flow reduction (sampling in 2004) and (ii) afterwards (study year 2011). Nesting males in 2004 (N = 31) and 2011 (N = 11) were measured, weighed and photographed in the field. The size of the total egg cluster (male reproductive success) was measured and photographed for each nest found (N = 137 in 2004 and N = 28 in 2011). Nesting area was measured to determine nest density for each sampling period. The degree of secondary sexual traits ( SSTs) development was measured later through the photographs. The age of males was assigned according to the length-intervals established by Vinyoles and De Sostoa (2007) for this species in the same study area. After flow reduction in 2011, the flooded area of the river bed was reduced by more than 80%. A great proportion of small males (1 year old) with developed SSTs (cephalic crest and anal glands) were found to defend a nest. This is the first time that parental care is found for the male of the freshwater blenny at a young age. Total cluster size (mean ± SE) is halved under the low flow conditions (from 45.4 ± 2.8 cm2 to 22.9 ± 2.7 cm2), but an increase in the number of partial clusters per nest was found. This study highlights the sexual plasticity of freshwater blenny males depending on environmental conditions and the vulnerability of this endangered species to the hydrological changes of anthropogenic origin in Spain. [ABSTRACT FROM AUTHOR]

Although effects of paternal deprivation on offspring have been previously studied, the factors initiating and maintaining paternal care are not very clear. Using socially monogamous mandarin voles, we investigated whether cues from dams affect paternal behaviours. The sires were separated from their pups individually or placed with dams immediately prior to paternal behaviour testing. The results showed that sires kept with dams displayed more huddling behaviour and shorter latency of retrieving than sires isolated individually. Sires placed with dams in a closed box also exhibited less huddling behaviour and longer latency of retrieving than sires placed with dams in an open box. In addition, anosmia, deafness or combination of these two treatments all significantly reduced huddling and licking behaviour compared with sham-operated group respectively. These results suggest that communication between sires and dams especially via olfactory and auditory signals plays an important role in strengthening paternal behaviours. [ABSTRACT FROM AUTHOR]

In the current paper the direct additive and maternal genetic effects on birth, weaning (at 90 days of age), and scanning (at 20 weeks of age) weights and muscle and fat depths of the ribeye area in Karayaka lambs were investigated. Analyses were carried out by the restricted maximum likelihood approach, fitting 6 animal models with various combinations of direct and maternal effects. The best model was chosen after testing for improvement in the log-likelihood values. Direct heritability (h2d) for all traits decreased when maternal genetic effects were included in the models. The maternal heritability (h2m) ranged from 0.15 to 0.22 for birth weight, from 0.04 to 0.14 for weaning weight, and from 0.08 to 0.16 for scanning weight. The effects of h2m on muscle depth and fat depth of the ribeye area were not considered due to their insignificance. The permanent environmental effect of the dam was significant for birth, weaning, and scanning weights. Moderate negative genetic correlations (ram) between the direct and maternal genetic effects were observed, which were significant for birth (-0.179 and -0.221), weaning (-0.310 and -0.415), and scanning (-0.116 and -0.141) weights. As a result, h2d and h2m can be used as selection criteria for birth, weaning, and scanning weights in Karayaka lambs. [ABSTRACT FROM AUTHOR]

Adult-directed predation risk elevates costs of parental care, and may modify relationships between sexually selected ornaments and parental effort by accentuating the tradeoff between survival and parental investment. We assessed multiple hypotheses regarding the relationship between maternal effort, paternal effort, and the sexually selected trait of male song complexity in the song sparrow Melospiza melodia. Further, we explored whether experimentally elevating perceived adult-directed predation risk near nests affected these relationships. We quantified two dimensions of song complexity: song repertoire size and residual syllable number (the relative number of syllables for a given song repertoire size). Under elevated perceived predation risk, but not in the absence of the predator stimuli, females mated to males with higher residual syllable number displayed higher nestling provisioning rates and performed a greater proportion of nestling provisioning trips. In other words, elevating perceived predation risk induced a pattern of maternal investment consistent with differential allocation. In contrast, under elevated perceived predation risk, only, females performed a lesser proportion of provisioning trips when mated to males with large song repertoire sizes. Further, consistent with the good parent hypothesis, males with large song repertoire sizes displayed lower latencies to return to the nest, independent of the predator stimuli. Results suggest that residual syllable number may reflect some aspect of male genetic quality, such that females are more willing to maintain maternal effort while facing heightened predation risk. On the other hand, females may gain paternal benefits when mated to males with large song repertoires. Our study supports the hypothesis that increased costs of parental care associated with predation risk may induce relationships between sexually selected traits and parental behavior, which may increase the strength of sexual selection. Additionally, results suggest that different aspects of song complexity may fulfill non-equivalent signaling roles. [ABSTRACT FROM AUTHOR]

The neuropeptides oxytocin and vasopressin have been implicated in exercise, as well as monogamy and parental behavior. In this study, we compared behavioral and neuroendocrine effects of access to an exercise wheel vs. the sedentary state typical in lab animal housing. Male prairie voles ( Microtus ochrogaster ) were studied because of their extensive repertoire of social behaviors including pair bond formation and biparental care, which are influenced by oxytocin and vasopressin. Subjects in one group had access to a running wheel in their cage (wheel), and voluntarily ran approximately 1.5 km/day for six weeks; these animals were compared to males in standard housing conditions ( n = 10/group). Males allowed to exercise formed partner preferences significantly faster than controls and exhibited fewer oxytocin neurons, as measured by immunohistochemistry in the bed nucleus of the stria terminalis. We observed no differences in terms of anxiety-related behavior, or alloparental responsiveness. Males with a running wheel equipped cage gained more total body weight, and by the end of the six weeks were found to have less subcutaneous fat and larger testes as a percentage of bodyweight. The changes to gonadal regulation and pair-bonding behavior associated with voluntary exercise are discussed in terms of their possible relevance to the natural history of this species. [ABSTRACT FROM AUTHOR]

Parental protection of offspring is found in numerous animal species. Protection provides offspring with a greater chance of surviving to be able to reproduce, while at the same time, often posing a cost to the parent. Therefore, the net value of defence for the parent can vary depending on the developmental stage of the offspring and their ability to defend themselves. For example, in commonly studied organisms (e.g. birds), defence level increases over time until offspring are able to leave the nest and parental defence wanes. We examine these nest defence decisions in the solitary bee system that poses an interesting variation to traditionally studied organisms. Nest value does not increase in a simple additive manner as offspring are added to the nest. Here, individual investments are allocated to each offspring, then as a final act, the nest entrance is sealed. This sealing action provides increased protection for all developing offspring in the nest, therefore strongly increasing their value. Our observational experiment using Megachile rotundata found that mothers slightly increased nest defence as nest size increased. However, unlike traditionally studied organisms, this increase in defence continued until the nest was completed. [ABSTRACT FROM AUTHOR]

Fear reactions in horses are a major cause of horse-human accidents, and identification of effective pathways for reduction in fearfulness can help decreasing the frequency of accidents. For a young mammal, the mother is one of the most salient aspects of its environment, and she can have a strong influence on her offspring's behaviour. This study investigated whether fearfulness in foals can be reduced through weekly exposure to usually frightening objects with a habituated mother during the first 8 weeks of life. Prior to foaling, mares ( N = 22) were habituated to five initially fear-eliciting situations, including exposure to novel stationary and moving objects. At birth, the foals were randomly assigned to either a Demonstration group ( N = 11) or a Control group ( N = 11). Demonstration mares demonstrated habituation towards the objects to their foals once per week in weeks 1-8 post-partum. Control mares were inside the empty test arena with their foals for the same amount of time. The foals were tested at 8 weeks and 5 months of age in four standardised fear tests. Demonstration foals showed significantly reduced fear responses (behaviour and heart rate) and increased exploratory behaviour at both 8 weeks and 5 months of age. The effect was likely achieved through a combination of maternal transmission and individual learning. It is concluded that fearfulness in foals may be reduced through exposure to frightening objects together with their habituated mother during the first 8 weeks of life. [ABSTRACT FROM AUTHOR]

The expression of key traits like parental provisioning and offspring begging is confounded by the parent-offspring conflict in species with parental care, with offspring seeking greater parental investment than parents are willing to provide. Given the reciprocal interplay of these traits, selection has likely favored specific parent-offspring trait combinations, and it has been a longstanding question which party benefits most from this linkage. This will become apparent in a mismatch situation, which we here experimentally created by reciprocally cross-fostering blue tit broods. We hypothesized that offspring fledgling mass and their excreted corticosterone metabolite (CM) levels (reflecting stress) should vary with the rate of (foster) parental care (if provisioning is under full parental control), with offspring begging (if offspring is fully in control), or an interaction of both traits reflecting stable end points along a power continuum. We found a significant interaction effect, that is, highly demanding broods reached lowest fledgling mass when raised by low providing parents (due to partly unrewarded costly begging) but highest fledgling mass when raised by high providers. This pattern, however, was not reflected in offspring CM levels. Parental provisioning of the foster parents affected CM levels again in interaction with the offspring's begging level, but this pattern may rather reflect intensity and frequency of sibling competition. Taken together, our results suggest that an adjustment of the offspring's phenotype to the post-hatching social environment is primarily beneficial for highly demanding offspring and that parents have the upper hand (but probably not full control) over provisioning. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue “Parental Care”. The reproductive experience of pregnancy, lactation and motherhood can significantly remodel the female's biological state, affecting endocrine, neuroendocrine, neural, and immunological processes. The brain, pituitary gland, liver, thymus, and mammary tissue are among the structures that are modified by reproductive experience. The present review that focuses on rodent research, but also includes pertinent studies in sheep and other species, identifies specific changes in these processes brought about by the biological states of pregnancy, parturition, and lactation and how the components of reproductive experience contribute to the remodeling of the maternal brain and organ systems. Findings indicate that prior parity alters key circulating hormone levels and neural receptor gene expression. Moreover, reproductive experience results in modifications in neural processes and glial support. The possible role of pregnancy-induced neurogenesis is considered in the context of neuroplasticity and behavior, and the effects of reproductive experience on maternal memory, i.e. the retention of maternal behavior, together with anxiety and learning are presented. Together, these sets of findings support the concept that the neural and biological state of the adult female is significantly and dramatically altered on a long-term basis by the experiences of parity and motherhood. Remodeling of the maternal brain and other biological systems is posited to help facilitate adaptations to environmental/ecological challenges as the female raises young and ages. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue “Parental Care”. Jay Rosenblatt effectively promoted research on rabbit maternal behavior through his interaction with colleagues in Mexico. Here we review the activities of pregnant and lactating rabbits ( Oryctolagus cuniculus ), their neuro-hormonal regulation, and the synchronization of behavior between mother and kits. Changing concentrations of estradiol, progesterone, and prolactin throughout gestation regulate nest-building (digging, straw-carrying, fur-pulling) and prime the mother's brain to respond to the newborn. Nursing is the only mother–young contact throughout lactation. It happens once/day, inside the nest, with ca. 24 h periodicity, and lasts around 3 min. Periodicity and duration of nursing depend on a threshold of suckling as procedures reducing the amount of nipple stimulation interfere with the temporal aspects of nursing, though not with the doe's maternal motivation. Synchronization between mother and kits, critical for nursing, relies on: a) the production of pheromonal cues which guide the young to the mother's nipples for suckling; b) an endogenous circadian rhythm of anticipatory activity in the young, present since birth. Milk intake entrains the kits' locomotor behavior, corticosterone secretion, and the activity of several brain structures. Sibling interactions within the huddle, largely determined by body mass at birth, are important for: a) maintaining body temperature; b) ensuring normal neuromotor and social development. Suckling maintains nursing behavior past the period of abundant milk production but abrupt and efficient weaning occurs in concurrently pregnant-lactating does by unknown factors. Conclusion: female rabbits have evolved a reproductive strategy largely dissociating maternal care from maternal presence, whose multifactorial regulation warrants future investigations. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue “Parental Care”.Across mammalian species, mothers shape socio-emotional development and serve as essential external regulators of infant physiology, brain development, behavior patterns, and emotional regulation. Caregiving quality, consistency and predictability shape the infant's underlying neurobiological processes. Although the requirements for “optimal” caregiving differ across species, the negative long-term consequences of the absence of needed caregiving (e.g. neglect) or the presence of harmful/aversive caregiving (e.g. physical abuse), are translatable across species. Recognizing the significant potential of cross species comparisons in terms of defining underlying mechanisms, effective translation requires consideration of the evolutionary, ecological, and fundamental biological and developmental differences between and among species. This review provides both an overview of several success stories of cross-species translations in relation to negative caregiving and a template for future studies seeking to most effectively define the underlying biological processes and advance research dedicated to mitigating the lasting negative health consequences of child maltreatment. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue “Parental Care”.Until recently, evolutionists reconstructing mother–infant bonding among human ancestors relied on nonhuman primate models characterized by exclusively maternal care, overlooking the highly variable responsiveness exhibited by mothers in species with obligate reliance on allomaternal care and provisioning. It is now increasingly recognized that apes as large-brained, slow maturing, and nutritionally dependent for so long as early humans were, could not have evolved unless “alloparents” (group members other than genetic parents), in addition to parents, had helped mothers to care for and provision offspring, a rearing system known as “cooperative breeding.” Here I review situation-dependent maternal responses ranging from highly possessive to permissive, temporarily distancing, rejecting, or infanticidal, documented for a small subset of cooperatively breeding primates. As in many mammals, primate maternal responsiveness is influenced by physical condition, endocrinological priming, prior experience and local environments (especially related to security). But mothers among primates who evolved as cooperative breeders also appear unusually sensitive to cues of social support . In addition to more “sapient” or rational decision-making, humankind's deep history of cooperative breeding must be considered when trying to understand the extremely variable responsiveness of human mothers. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue on “Parental Care”. Maternal behavior has an important function in stimulating adequate growth and development of the young. Several approaches have been used in primates and rodents to deconstruct and examine the influence of specific components of maternal stimulation on offspring development. These approaches include observational studies of typical mother–infant interactions and studies of the effects of intermittent or complete deprivation of maternal contact. In this review, we focus on one unique approach using rats that enables the complete control of maternal variables by means of rearing rat pups artificially without contact with the mother or litter, while maintaining stable nutrition, temperature and exposure to stressful stimuli. This artificial rearing model permits the removal and controlled replacement of relevant maternal and litter stimuli and has contributed valuable insights regarding the influence of these stimuli on various developmental outcomes. It also enables the analysis of factors implicated in social isolation itself and their long-term influence. We provide an overview of the effects of artificial rearing on behavior, physiology, and neurobiology, including the influence of replacing maternal tactile stimulation and littermate contact on these outcomes. We then discuss the relevance of these effects in terms of the maternal role in regulating different aspects of offspring development and implications for human research. We emphasize that artificial rearing of rats does not lead to a global insult of nervous system development, making this paradigm useful in investigating specific developmental effects associated with maternal stimulation. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue "Parental Care". Although paternal care is generally rare among vertebrates, care of eggs and young by male birds is extremely common and may take on a variety of forms across species. Thus, birds provide ample opportunities for investigating both the evolution of and the proximate mechanisms underpinning diverse aspects of fathering behavior. However, significant gaps remain in our understanding of the endocrine and neuroendocrine influences on paternal care in this vertebrate group. In this review, I focus on proximate mechanisms of paternal care in birds. I place an emphasis on specific hormones that vary predictably and/or unpredictably during the parental phase in both captive and wild birds: prolactin and progesterone are generally assumed to enhance paternal care, whereas testosterone and corticosterone are commonly—though not always correctly—assumed to inhibit paternal care. In addition, because endocrine secretions are not the sole mechanistic influence on paternal behavior, I also explore potential roles for certain neuropeptide systems (specifically the oxytocin–vasopressin nonapeptides and gonadotropin inhibitory hormone) and social and experiential factors in influencing paternal behavior in birds. Ultimately, mechanistic control of fathering behavior in birds is complex, and I suggest specific avenues for future research with the goal of narrowing gaps in our understanding of this complexity. Such avenues include (1) experimental studies that carefully consider not only endocrine and neuroendocrine mechanisms of paternal behavior, but also the ecology, phylogenetic history, and social context of focal species; (2) investigations that focus on individual variation in both hormonal and behavioral responses during the parental phase; (3) studies that investigate mechanisms of maternal and paternal care independently, rather than assuming that the mechanistic foundations of care are similar between the sexes; (4) expansion of work on interactions of the neuroendocrine system and fathering behavior to a wider array of paternal behaviors and taxa (e.g., currently, studies of the interactions of testosterone and paternal care largely focus on songbirds, whereas studies of the interactions of corticosterone, prolactin, and paternal care in times of stress focus primarily on seabirds); and (5) more deliberate study of exceptions to commonly held assumptions about hormone–paternal behavior interactions (such as the prevailing assumptions that elevations in androgens and glucocorticoids are universally disruptive to paternal care). Ultimately, investigations that take an intentionally integrative approach to understanding the social, evolutionary, and physiological influences on fathering behavior will make great strides toward refining our understanding of the complex nature by which paternal behavior in birds is regulated. [ABSTRACT FROM AUTHOR]

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 formof care and, when confronted with an increase in the abundance of extrapair mating prospects, they reduce the time they commit to incubation. [ABSTRACT FROM AUTHOR]

Behavioural flexibility is essential for survival in a world with changing contingencies and its evolution is linked to complex physical and social environments. Serial reversal learning, in which reward contingencies change frequently, is a key indicator of behavioural flexibility. While many vertebrates are capable of serial reversal learning, only birds and mammals have previously been shown to use rulebased decision strategies (e.g. win-stay/lose-shift) to become better at learning changes in reward contingencies across reversals. While the lifestyles of many amphibians have a degree of complexity, the evidence to date suggests limited levels of behavioural flexibility. Here, we show that the poison frog Dendrobates auratus, which has evolved complex parental behaviours that likely depend on remembering locations in a flexible manner, can use a win-stay/lose-shift strategy to increase their behavioural flexibility across sequential changes in the reward contingencies in a visual discrimination task. Furthermore, probe trials demonstrate that the frogs used the provided visual cues to spatially orient in the maze in a manner reminiscent of complex spatial cognition. Our study provides the first evidence of serial reversal learning in frogs and is the first to demonstrate the use of a rule-based learning strategy in a nonavian, nonmammalian species. [ABSTRACT FROM AUTHOR]

Sexual conflict arises whenever males and females have divergent reproductive interests. The mechanisms mediating the resolution of sexual conflict have been studied extensively in the context of parental care, where each parent adjusts its decision about how much care to provide based on its partner's workload. However, there is currently no information on the mechanisms mediating the resolution of sexual conflict over personal consumption from a shared resource. We address this gap in the burying beetle Nicrophorus vespilloides, which breeds on small vertebrate carcasses. The carcass serves as a source of food for both the developing larvae and the caring parents, and parents feed from the carcass for selfmaintenance. To study the mechanisms mediating conflict resolution, we experimentally varied the two parents' body size to create variation in carcass consumption. We then assessed whether each parent adjusted its consumption based on its own size, its partner's size and its partner's consumption. As expected, large parents gained more mass than small parents. Furthermore, males paired to large females gained more mass than males paired to small females, and females responded to their partner's mass change, gaining more mass when their partner did. Our study provides insights into the resolution of a new form of sexual conflict, showing that it is mediated through both matching and sealed-bid responses. Our findings also suggest that the resolution models developed in the context of sexual conflict over biparental care may apply more generally than previously thought. [ABSTRACT FROM AUTHOR]

Sexually selected traits can signal an individual's ability to contribute offspring care. Differential allocation theory posits that when these same traits also influence brood value, it may be adaptive for partners to adjust care in response to their mates' traits. Evaluating the strength and direction of parental quality signalling and differential allocation is thus essential to understand selection on ornamental traits. We examined relationships between plumage colour and parental care in tree swallows, Tachycineta bicolor, a mutually ornamented species in which plumage colour is related to male and female reproductive performance. Using a model of avian vision to quantify parental colour trait variation, we found that male and female tree swallows that were paired to partners with greener, more saturated plumage colour fed offspring at higher rates. Among tree swallow pairs where both partners were in their second year of breeding or older, individuals with greener, more saturated plumage colour also fed their offspring at higher rates. We show that offspring of males that provisioned more often tended to achieve greater body mass independent of the colour traits of their parents. Our results suggest a role for partner parental care in selection on female ornamentation in this species. [ABSTRACT FROM AUTHOR]

Parental care is important for offspring success for many animals. Both male-only and female-only care occur equally often among frogs, creating opportunities to examine ecological factors that may favor sex-specific patterns of care. Experimental tests of care function can elucidate such factors and identify benefits of parental behavior to offspring. In glassfrogs (Centrolenidae), only male egg attendance has been documented and male care is thought to have evolved repeatedly from a state of no-care. We provide experimental evidence demonstrating female care in the glassfrog Ikakogi tayrona-a species sister to all other members of the family. We used repeated observations to quantify egg attendance behaviors, and a removal experiment to evaluate the benefits of maternal care and test whether care function changes with embryonic development. Given the importance of care to female fitness, we examined maternal commitment to providing care in risky situations, using a simple behavioral challenge. We found that egg attendance reduces embryo dehydration and predation. Moreover, the specific benefits of care changed across embryo development, suggesting that different threats to embryos select for egg attendance at different stages. The maternal commitment assay revealed that caring females are more risk-tolerant than non-caring females. Our finding of maternal care in I. tayrona reveals previously unknown diversity in glassfrog parental care and contributes to emerging evidence that care functions are similar among frogs with female-only and male-only egg attendance. This suggests that a lack of sex-specific constraints may have facilitated evolutionary changes in sex roles. [ABSTRACT FROM AUTHOR]

Parental care is a key evolutionary innovation that influences the fitness of parents and offspring. How the brain coordinates such a complex behavior remains poorly understood. Kohl and colleagues recently uncovered the organizational principles of hypothalamic galanin neurons and their connections in mice. Their findings revealed a striking picture in which discrete neuronal pools control distinct aspects of parental behavior. [ABSTRACT FROM AUTHOR]

The article discusses reasons for which some animals carry their offspring while others do not by using birds as an example. The author states that in birds, carrying chicks on the back is perhaps most widespread in the grebes and they do so for brooding purpose and due to high degree of family mobility. The author also states that one potential benefit to carrying chicks could be decreased risk of predation for chicks.