Affect Offspring Survival Research Articles

Fear of predators reduces body and physiological condition affecting offspring survival and the ‘quality’ of the survivors

Abstract Predators affect the survival of developing young by eating them. More recently, the fear of being eaten has been uncovered as a powerful driver of offspring survival reducing recruited offspring numbers by 53%, but the mechanisms driving these effects are not well understood. We exposed song sparrows to predator or non‐predator playbacks throughout three breeding seasons. We followed offspring as eggs through development and into maturity. We quantified the repercussions of being reared in a fearful environment on body (fat, mass, size) and physiological condition using 12 different measures categorized into six systems (oxygen carrying capacity, energy reserves, immune function, antioxidant protection, oxidative stress/damage, glucocorticoids). We further tracked offspring survival in the nest to maturity and determined which measures of condition significantly predicted survival. We report that fear of predators affected offspring condition at all stages of life, with survival consequences. Predator‐playback offspring hatched from heavier eggs (8%) but quickly lost this advantage and never regained it. Nestlings reared by ‘frightened’ parents were as heavy and much leaner than non‐predator playback nestlings. This pattern extended throughout development into maturity where offspring reared by frightened parents were up to 31% leaner and 5% lighter. Predator‐playback nestlings also were evidently in poorer physiological condition, having shorter telomeres, while late dependency stage fledglings carried relatively less uric acid and more haptoglobin perhaps indicative of chronic susceptibility to infection. Only body condition (mass and fat) predicted survival during peak mortality periods (nestling and early fledging), with the leanest lightest offspring from the predator‐playback treatment being least likely to survive. Thereafter, mass predicted survival irrespective of playback treatment. Similarly, at this later stage, offspring with less telomere loss and high uric acid levels survived best regardless of playback group. Our findings reveal that fear of predators is a potent form of early life adversity which persistently alters the condition of offspring affecting early stage survival and the ‘quality’ of the survivors throughout their life. Development is fuelled by food and fear‐induced reductions in parental provisioning at the earliest stages likely instigated these effects, with consequences on the population growth rate. Read the free Plain Language Summary for this article on the Journal blog.

Sex‐specific oviposition site selection in an arboreal treefrog with a resource‐defense mating system

AbstractOviposition site selection by parents is an important factor that affects offspring survival and parental fitness. The relative importance of sexes in oviposition site selection in anurans is rarely evaluated, especially in species with resource‐defense mating systems, where males defend territory containing eventual oviposition sites before advertising for females. Using a phytotelm‐breeding frog (Kurixalus eiffingeri) with male territoriality, we examined 310 bamboo stumps (potential for oviposition sites) to determine whether male and female choice of oviposition site based on physical characteristics (stump height, inner diameter, stump depth, water depth, and water volume). We found that males preferred a site with higher stumps that were deeper and contained more water, while females showed no preference for sites based on the characteristics observed. Although we do not exclude the possibility that K. eiffingeri female oviposition site selection can be relied on and/or correlates to male advertisement calls, this study is one of few studies to examine the role of both sexes in oviposition site selection simultaneously, and provides empirical evidence that oviposition site selection is primarily determined by males in an amphibian with a resource‐defense mating system.

A PRELIMINARY INVESTIGATION OF PATHOGEN EXPOSURE OF ADULT FEMALE WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) AND SURVIVAL OF ASSOCIATED FAWNS IN THE WESTERN DAKOTAS, USA.

Exposure of a dam to pathogens may potentially affect her fawns positively or negatively. Mammalian females transfer immunologic protection to their offspring via colostrum obtained while nursing. Conversely, chronic diseases in dams may potentially result in small and weak neonates, reduced milk production or quality, or infection. Little is known about how pathogen exposure in adult female white-tailed deer (Odocoileus virginianus) affects offspring survival. Our objective was to assess pathogen exposure for female white-tailed deer and subsequent survival rates of fawns in Dunn and Grant counties, North Dakota, and Perkins County, South Dakota, USA. We collected blood serum from 150 adult female deer during 2014. We compared survival of 49 fawns to maternal exposure to 10 pathogens from 37 of 150 adult females. There was no difference in fawn mass between dams based on antibody status and no difference in fawn survival for nine pathogens. The 12-wk survival for fawns born to mothers with antibodies against bovine herpesvirus 1 (BoHV-1, causing infectious bovine rhinotracheitis) was lower than for fawns born from mothers without antibodies against BoHV-1; however, the indirect or direct impacts of BoHV-1 exposure in mothers on fawn survival are unclear. Although our findings suggest that the cost of exposure to previous diseases may have minimal impact on short-term fawn survival for most pathogens, additional research with increased sample sizes is needed to confirm our findings.

Egg components and offspring survival vary with group size and laying order in a cooperative breeder

Prenatal resource allocation to offspring can be influenced by maternal environment and offspring value, and affect offspring survival. An important pathway for flexible maternal allocation is via egg components such as nutrients and hormones. In cooperative breeders, females with helpers may increase resource allocation to eggs—‘differential allocation’—or reduce it—‘load-lightening’. Yet, helper effects on egg composition have been poorly studied. Moreover, it is unknown how helpers’ presence modulates laying order effects on egg content and survival. Here, we investigated how maternal allocation varied with group size and laying order in the cooperatively breeding sociable weaver (Philetairus socius). We estimated interactive effects of helpers and laying order on allocation to egg mass, yolk nutrients—yolk mass, proteins, lipids, carotenoids, vitamin A and vitamin E—and hormones—testosterone, androstenedione, and corticosterone. Results concurred with the ‘differential allocation’ predictions. Females with more helpers produced later-laid eggs with heavier yolks and more lipids, and laid eggs overall richer in lipids. Proteins, antioxidants, and hormones were not found to vary with helper number. We then analyzed how helper number modulated laying order effects on survival. Females with more helpers did not specifically produce later-laid eggs with higher survival, but eggs laid by females with more helpers were overall more likely to fledge. These findings show that some egg components (yolk mass, lipids) can positively vary according to females’ breeding group size, which may improve offspring fitness.

Anthropogenic and biological sound effects on the maternal care behavior of a key crab species

IntroductionMaternal care in marine decapods involves eggs caring in the brood compartment until the larvae hatch. This behavior mainly allows embryo mass oxygen supply, ensuring healthy embryonic development. The present study aimed to analyze the effect of different sound sources (anthropogenic and biologic) and their temporal patterns (low and high rate: 1 min of the sound stimulus + 5 min of silence and 1 min of the sound stimulus + 1 min of silence, respectively) on the maternal care of the key crab species, Neohelice granulata.MethodsIn the laboratory, three acoustic stimuli were played back: an artificial white noise (10 Hz – 20 kHz), and two sounds obtained from the crabs´ natural habitat, motorboat passages and biological signals from a crabs’ predator fish. Three behavioral variables were quantified: still position, and two maternal care behaviors: abdominal flapping and chelae probing.ResultsResults demonstrated that the high rate anthropogenic stimuli, white noise and motorboat, affected all behavioral variables, increasing the still position and diminishing the maternal care behaviors. Otherwise, the predatory stimulus did not affect the still position although diminished the maternal care behaviors (high rate).DiscussionThe different behavioral response depending on the sound stimuli may indicate that crabs distinguish sound sources. The anthropogenic noise is suggested to cause distraction that is linked to the increased still position, while the predator stimulus would be associated with an alert behavior not affecting the locomotion behavior. The sound stimuli effect on the maternal care behavior revealed a negative effect that potentially could affect offspring survival. This is important considering the ecosystem engineering function of the studied key crab species. The reduction of the noise emission pattern rate is suggested as a mitigation action to diminish sound impact effects in the crab’s natural habitat. The study contributes the first to assessing the effect of different sound sources on the maternal care behavior of a crustacean species.

Costs and benefits of isolation from siblings during family life in adult earwigs

The benefits of parental care are often seen as a cornerstone of family life evolution. However, recent studies show that sibling interactions can also confer substantial benefits to juveniles. Here, we tested a new hypothesis suggesting that the need for juveniles to access sibling interactions may encourage juveniles to remain in a family group, thereby consolidating the early stages of family life evolution when parental care is facultative. We set up juveniles of the European earwig, Forficula auricularia (a family-living insect in which maternal care is facultative and juveniles can forage for themselves and cooperate with siblings) either alone, with siblings, or with siblings and their mother, and then quantified effects on the development, morphology and four fitness-related behaviours of the resulting adults. We found that isolated juveniles reached adulthood more quickly and that these adults were overall larger but showed impaired aggregation behaviour when compared with juveniles raised together with siblings or with siblings and their mother. By contrast, sibling deprivation did not affect offspring survival, male forceps length (an ornament involved in reproductive success) and three other behaviours in adults (boldness, general activity and exploration). All these results were independent of adult sex, although females overall reached adulthood earlier and were larger than males. Altogether, our findings suggest that the potential benefits of sibling interactions measured in this study play a minor role in the maintenance of earwig family life. They also emphasize the need to study the evolutionary drivers of family life in species where all members can switch from family to solitary life, a scenario that probably prevailed in the early evolution of sociality. • Do the benefits of sibling interactions support the maintenance of family life? • We addressed this question by testing the effects of sibling deprivation in earwigs. • We found that it produces adults with impaired aggregation and faster development. • But it has no effect on survival and three other fitness-related behaviours. • This questions the role of sibling interactions in the emergence of family life.

Nest defence behaviour is similar between pair members but only male behaviour predicts nest survival in barnacle geese

Behavioural patterns often differ consistently across individuals and are linked to fitness. In species with biparental care, the defence behaviour of both parents can affect reproductive success through offspring survival. In addition to the intensity of defence behaviour by both pair members, the similarity in this behaviour among parents may affect offspring survival. However, few studies have investigated the relative impact of both the intensity and similarity of defence behaviour. Here, we examined nest defence behaviour of males and females during the incubation stage in an Arctic population of barnacle geese Branta leucopsis. We calculated the repeatability of defence behaviour to test whether this behaviour is consistent within individuals and investigated how it is associated with age. In addition, we investigated how daily survival rate (DSR) of the nests until hatching is associated with nest defence behaviour and age of the parents, as well as the effect of parent similarity in nest defence behaviour as an emergent trait of the pair bond. Both male and female defence behaviour were highly repeatable. The ages of both partners within breeding pairs were positively related, but age was only significantly associated with defence behaviour in females. Further, we found high similarity in defence behaviour within breeding pairs, but the similarity and intensity of defence behaviour within breeding pairs did not predict DSR. Finally, male defence behaviour positively predicted DSR, but female defence behaviour and male and female age did not. Our results suggest that nest protection is adaptive in males but behavioural similarity of pair members does not enhance nest survival, indicating behavioural similarity itself is not adaptive but rather a by‐product of different effects.

Seasonal weather effects on offspring survival differ between reproductive stages in a long-lived neotropical seabird.

Weather conditions can profoundly affect avian reproduction. It is known that weather conditions prior to and after the onset of reproduction can affect the breeding success of birds. However, little is known about how seasonal weather variability can affect birds' breeding performance, particularly for species with a slow pace of life. Long-term studies are key to understanding how weather variability can affect a population's dynamics, especially when extreme weather events are expected to increase with climate change. Using a 32-year population study of the Blue-footed booby (Sula nebouxii) in Mexico, we show that seasonal variation in weather conditions, predominantly during the incubation stage, affects offspring survival and body condition at independence. During most of the incubation period, warm sea surface temperatures were correlated with low hatching success, while rainfall in the middle of the incubation stage was correlated with high fledging success. In addition, chicks from nests that experienced warm sea surface temperatures from the pre-laying stage to near-fledging had lower body condition at 70days of age. Finally, we show that variable annual SST conditions before and during the incubation stage can impair breeding performance. Our results provide insight into how seasonal and interannual weather variation during key reproductive stages can affect hatching success, fledging success, and fledgling body condition in a long-lived neotropical seabird.

Influence of environmental factors and body condition on the post-oviposition behavior in the emerald glass frog Espadarana prosoblepon (Centrolenidae).

In species with parental care behaviors, parents may adjust the intensity and duration of their care if fluctuation in factors such as environmental variables or body condition affects offspring survival. In the face of environmental changes, many egg-laying species remain with their clutch for extended periods if this behavioral adjustment provides tangible benefits to the offspring. However, the length of time parents stay with the offspring may also differ depending on the individual’s body condition. In the glass frog family (Centrolenidae), several species exhibit long-term egg attendance in which they remain with their clutch for several days after oviposition takes place. For some of them, changes in environmental variables lead to increased parental care efforts. For the species in which parents remain with their offspring for a short period (less than 24 hours), it is less clear if this constitutes parenting behavior, and whether parents adjust their efforts as a function of environmental change or the parent’s body condition remains unexplored. We studied a population of the Emerald Glass Frog, Espadarana prosoblepon, a species that exhibits a short period of quiescence after oviposition (less than three hours). Our study aimed to determine whether females alter the length of their post-oviposition quiescence period in response to changes in environmental variables (i.e., temperature, humidity, rainfall, and mean wind speed) or female body condition. Pairs in amplexus were captured in the field and transported to semi-natural enclosures to record the duration of post-oviposition quiescence using infrared cameras. Females’ post-oviposition quiescence lasted an average of 67.4 ± 26.6 min (range = 22.7–158.3 min). We did not find a significant relationship between the duration of the post-oviposition quiescence and any of the environmental variables tested. Similarly, post-oviposition quiescence duration was not influenced by female body condition. Because the variation observed in the duration of post-oviposition quiescence was not related to changes in extrinsic (environmental) or intrinsic (body condition) factors, we found no evidence that females of E. prosoblepon modify their post-oviposition behavior in response to any of the variables examined in this study. Future research investigating the adaptive significance of the post-oviposition quiescence observed in this species is needed to understand how this behavior is related to parental care efforts.

Effects of population density on adult morphology and life-history traits of female Mediterranean flour moth, Ephestia kuehniella (Lepidoptera: Pyralidae)

Intraspecific competition and food shortage due to high population density during early life can have a profound effect on adult fitness. Organisms often mitigate negative effects of high population density by adjusting resource allocation to adult morphological and life-history traits. In Lepidoptera with short-lived adults that do not feed, it is predicted that females developed from dense larval aggregations invest more in reproduction and traits linked to offspring survival. Here, we investigated the effects of larval population density on adult morphology and life-history traits in the female Mediterranean flour moth, Ephestia kuehniella by raising larvae at a range of population densities. Adults from high population density (16 larvae per g of food) had smaller head, thorax, and forewing compared to other densities. The allometric slope of forewing length with body mass did not differ among population densities, indicating no changes in adult wing morphology at high population density. However, we found that females emerged from larvae at high population density had bigger abdomens relative to body mass, indicating resource investment in reproduction, probably to mitigate the negative effects of crowding on egg production. Ovipositor length did not differ among population densities, indicating conservation of resources to structures with egg-laying function that affect offspring survival. Taken together, these results suggest that female E. kuehniella responding to high larval population density invest relatively more in reproduction, a life-history strategy that could alleviate negative effects of population density on fitness. This study also highlights the importance of a species' reproductive strategy in its adaptive response to environmental conditions, which is relevant to many capital breeders dependent on larval resources for reproduction.

Pre-fertilization exposure of sperm to nano-sized plastic particles decreases offspring size and swimming performance in the European whitefish (Coregonus lavaretus)

Exposure of aquatic organisms to micro- and nano-sized plastic debris in their environment has become an alarming concern. Besides having a number of potentially harmful impacts for individual organisms, plastic particles can also influence the phenotype and performance of their offspring. We tested whether the sperm pre-fertilization exposure to nanoplastic particles could affect offspring survival, size, and swimming performance in the European whitefish Coregonus lavaretus. We exposed sperm of ten whitefish males to three concentrations (0, 100 and 10 000 pcs spermatozoa−1) of 50 nm carboxyl-coated polystyrene spheres, recorded sperm motility parameters using computer assisted sperm analysis (CASA) and then fertilized the eggs of five females in all possible male-female combinations. Finally, we studied embryonic mortality, hatching time, size, and post-hatching swimming performance of the offspring. We found that highest concentration of plastic particles decreased sperm motility and offspring hatching time. Furthermore, sperm exposure to highest concentration of plastics reduced offspring body mass and impaired their swimming ability. This suggests that sperm pre-fertilization exposure to plastic pollution may decrease male fertilization potential and have important transgenerational impacts for offspring phenotype and performance. Our findings indicate that nanoplastics pollution may have significant ecological and evolutionary consequences in aquatic ecosystems.

Neurotranscriptomic changes associated with chick-directed parental care in adult non-reproductive Japanese quail

For many species, parental care critically affects offspring survival. But what drives animals to display parental behaviours towards young? In mammals, pregnancy-induced physiological transformations seem key in preparing the neural circuits that lead towards attraction (and reduced-aggression) to young. Beyond mammalian maternal behaviour, knowledge of the neural mechanisms that underlie young-directed parental care is severely lacking. We took advantage of a domesticated bird species, the Japanese quail, for which parental behaviour towards chicks can be induced in virgin non-reproductive adults through a sensitization procedure, a process that is not effective in all animals. We used the variation in parental responses to study neural transcriptomic changes associated with the sensitization procedure itself and with the outcome of the procedure (i.e., presence of parental behaviours). We found differences in gene expression in the hypothalamus and bed nucleus of the stria terminalis, but not the nucleus taeniae. Two genes identified are of particular interest. One is neurotensin, previously only demonstrated to be causally associated with maternal care in mammals. The other one is urocortin 3, causally demonstrated to affect young-directed neglect and aggression in mammals. Because our studies were conducted in animals that were reproductively quiescent, our results reflect core neural changes that may be associated with avian young-directed care independently of extensive hormonal stimulation. Our work opens new avenues of research into understanding the neural basis of parental care in non-placental species.

Heritable responses to combined effects of heat stress and ivermectin in the yellow dung fly

In current times of global change, several sources of stress such as contaminants and high temperatures may act synergistically. The extent to which organisms persist in stressful conditions will depend on the fitness consequences of multiple simultaneously acting stressors and the genetic basis of compensatory genetic responses. Ivermectin is an antiparasitic drug used in livestock that is excreted in dung of treated cattle, causing severe negative consequences on non-target fauna. We evaluated the effect of a combination of heat stress and exposure to ivermectin in the yellow dung fly, Scathophaga stercoraria (Diptera: Scathophagidae). In a first experiment we investigated the effects of high rearing temperature on susceptibility to ivermectin, and in a second experiment we assayed flies from a latitudinal gradient to assess potential effects of local thermal adaptation on ivermectin sensitivity. The combination of heat and ivermectin synergistically reduced offspring survival, revealing severe effects of the two stressors when combined. However, latitudinal populations did not systematically vary in how ivermectin affected offspring survival, body size, development time, cold and heat tolerance. We also found very low narrow-sense heritability of ivermectin sensitivity, suggesting evolutionary constraints for responses to the combination of these stressors beyond immediate maternal or plastic effects. If the revealed patterns hold also for other invertebrates, the combination of increasing climate warming and ivermectin stress may thus have severe consequences for biodiversity. More generally, our study underlines the need for quantitative genetic analyses in understanding wildlife responses to interacting stressors that act synergistically and threat biodiversity.

Reduced reproductive success in voles Microtus arvalis and Myodes glareolus: Male presence negatively affects offspring survival and their growth rates

Reduced reproductive success in voles Microtus arvalis and Myodes glareolus: Male presence negatively affects offspring survival and their growth rates

Grow fast but don't die young: Maternal effects mediate life-history trade-offs of lizards under climate warming.

As postulated by life-history theory, not all life-history traits can be maximized simultaneously. In ectothermic animals, climate warming is predicted to increase growth rates, but at a cost to overall life span. Maternal effects are expected to mediate this life-history trade-off, but such effects have not yet been explicitly elucidated. To understand maternal effects on the life-history responses to climate warming in lizard offspring, we conducted a manipulative field experiment on a desert-dwelling viviparous lacertid lizard Eremias multiocellata, using open-top chambers in a factorial design (maternal warm climate and maternal present climate treatments×offspring warm climate and offspring present climate treatments). We found that the maternal warm climate treatment had little impact on the physiological and life-history traits of adult females (i.e. metabolic rate, reproductive output, growth and survival). However, the offspring warm climate treatment significantly affected offspring growth, and both maternal and offspring warm climate treatments interacted to affect offspring survival. Offspring from the warm climate treatment grew faster than those from the present climate treatment. However, the offspring warm climate treatment significantly decreased the survival rate of offspring from maternal present climate treatment, but not for those from the maternal warm climate treatment. Our study demonstrates that maternal effects mediate the trade-off between growth and survival of offspring lizards, allowing them to grow fast without a concurrent cost of low survival rate (short life span). These findings stress the importance of adaptive maternal effects in buffering the impact of climate warming on organisms, which may help us to accurately predict the vulnerability of populations and species to future warming climates.

Assessment of Asobara japonica as a potential biological control agent for the spotted wing drosophila, Drosophila suzukii

To assess the potential of Asobara japonica Belokobylskij (Hymenoptera: Braconidae) as a biological control agent for the invasive Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), key biological traits were evaluated: preference and suitability of different host ages, relative performance on two host species ( D. suzukii and Drosophila melanogaster Meigen), female life-time fecundity and egg maturation on the two host species, and parasitism levels on D. suzukii larvae infesting different host fruits (blackberry, cherry and strawberry). Asobara japonica preferred young over old hosts, and although host age did not affect offspring survival, parasitoid offspring developed faster in older than younger hosts but had a reduced body size. There was higher A. japonica offspring survival, longer developmental time, and larger body when reared from D. suzukii than D. melanogaster . Female wasps emerged with around one third of their lifetime egg load and matured eggs rapidly with mature egg load reaching a peak 2–3 d post-emergence. Large females (typically reared from D. suzukii ) contained more mature eggs than small females (typically from D. melanogaster ). During their lifetime, A. japonica females produced 117.4 and 92.5 progeny on D. suzukii and D. melanogaster , respectively, with a corresponding intrinsic rate of increase of 0.217 and 0.210, respectively. Progeny were strongly female-biased (> 90% females), regardless of host age or species. This larval parasitoid was able to develop from D. suzukii infesting cherry, blackberry or strawberry. This information may help improve protocols for the rearing and future evaluations of this parasitoid for a potential biological control program against D. suzukii .

Egg Clutch Survival under Prolonged Paternal Care in a Glass Frog, Hyalinobatrachium talamancae

Previous studies have reported egg attendance as the most common protective behavior among the Neotropical frog family Centrolenidae. However, research on the effect of parental care and other factors thought to affect offspring survival is still missing for a great number of species. Here, we performed field observations during day and night to associate male-only care, habitat characteristics, and environmental variables with egg clutch survival in the understudied glass frog, Hyalinobatrachium talamancae. We conducted 34 nest survival models for 39 egg clutches considering constant daily survival rates, temporal variation in the survival probability, and other biotic and abiotic variables thought to affect the survival of embryos. We found that egg attendance was strongly associated with egg clutch survival in H. talamancae. Our results showed similar degrees of parental investment during day and night, accounting for extensive caring periods over one or multiple clutches as paternal care did not hinder re-mating in this species. Egg clutches exhibited daily survival rates of 0.93±0.02, often reaching pre-hatching stages when attended by males. Our results may thus suggest that egg attendance is a major, if not predominant, determining factor of embryo survival in H. talamancae. This study contributes to the understanding of the natural history associated with paternal care in H. talamancae and provides insight into the evolution of prolonged male-only care in the family Centrolenidae.

Environmental and behavioral factors affect northern bobwhite offspring survival

Many environmental and behavioral factors can affect offspring survival, and these factors can vary by species. Parental investments, defense or distraction displays, and translocation can potentially affect survival of young. Alterations in parental investment strategies may carry implications for population growth due to lower offspring survival in translocated bobwhites. We hypothesized that translocation would not impact brood defense behaviors in bobwhites as predator communities may be similar between donor sites (Florida) and release sites (North Carolina). However, we hypothesized that brood defense behaviors affect offspring survival rates. We conducted defense behavior observations by approaching brood‐rearing bobwhites and recording exhibited behaviors, and assigned scores based on behavioral intensity. We used the corral capture method and modified‐suture technique to capture and radio‐tag bobwhite chicks. Brood defense behaviors did not differ between resident and translocated bobwhites. We observed seven different brood defense behaviors: fly away, run, labored flight, labored flight with broken wing display, run with broken wing display, hold tight and approach behaviors. We found that time‐varying precipitation and behavioral intensity affected bobwhite chick survival. These results indicate that translocation does not impact brood defense behaviors due to behavioral similarities between resident and translocated cohorts. These results portend that some variation in annual chick mortality cannot be mitigated by habitat management. We also provide evidence that translocation does not alter/suppress important behavioral patterns in bobwhite, indicating it is a viable method for restoring bobwhite populations in conjunction with habitat management.

Show me you care: female mate choice based on egg attendance rather than male or territorial traits

AbstractFemale mate choice is often based on male traits, including signals or behaviors, and/or the quality of a male’s territory. In species with obligate paternal care, where care directly affects offspring survival, females may also base their mate choices on the quality of a sire’s care. Here, we quantified male reproductive success in a natural population of the glass frog Hyalinobatrachium cappellei, a species with male parental care, to determine the influence of territory quality, male traits, and paternal care behaviors on female mate choice. We found that attending males have a higher chance of gaining new clutches than nonattending males. Our results indicate that females do not select males based only on body condition, calling persistence, or territory traits. Instead, our findings support the hypothesis that females choose males based on care status. Indeed, males already attending a clutch were 70% more likely to obtain another clutch, and the time to acquire an additional clutch was significantly shorter. We also found that males adjust their parental care effort in response to genetic relatedness by caring only for their own offspring; however, remaining close to unrelated clutches serves as a strategy to attract females and increase chances of successful mating. Thus, males that establish territories that already contain clutches benefit from the signal eggs provide to females.

Effects of Food Availability and Parental Risk Taking on Nestling Period Duration: A Field ExperimenT on the Pied Flycatcher Ficedula hypoleuca

The timing of fledging is critical in altricial birds as it affects offspring survival probability and thereby both parental and offspring fitness. The high vulnerability of offspring to predation soon after fledging may induce a parent-offspring conflict with respect to the age of fledging, as parents would benefit more than offspring from reducing the period of whole-brood vulnerability before fledging. Parents also benefit from inducing early fledging through reduced commuting costs and a decreased exposure to predators. A reliable food resource near the nest could thus favour a relaxation of parental drives to induce fledging and enable an approach to the optimal fledging age from the offspring point of view. A population of a cavity nester, the European Pied Flycatcher Ficedula hypoleuca, was offered food supplements (live mealworms) at the nest-box to randomly selected pairs throughout the nestling period and fledging ages were compared with those at nests without supplements. Provisioning parents were also trapped at the nest-box to estimate their willingness to incur predation risks in terms of easiness of capture (trappability). Fledging ages ranged from 15 to 20 days. Fledging was delayed in food-supplemented nests (n = 21) compared with control nests (n = 20) by one day on average, a significant difference. This was not due to the size and mass of nestlings at 13 days, which were similar under both treatments. Moreover, fledging age was positively related to parental trappability. Parents with easy access to food near the nest and those more willing to risk predation were those whose nestlings fledged at older ages. Parents apparently adjust the timing of offspring fledging to their foraging costs.—Moreno, J. (2020). Effects of food availability and parental risk taking on nestling period duration: a field experiment on the Pied Flycatcher Ficedula hypoleuca. Ardeola, 67: 29-38.