Females In Poor Body Condition Research Articles

Differential allocation in a gift-giving spider: males adjust their reproductive investment in response to female condition

BackgroundWhen males are selective, they can either reject low-quality females or adjust their reproductive investment in response to traits that indicate female quality (e.g., body size or condition). According to the differential allocation hypothesis, males increase their reproductive investment when paired with high-quality females (positive differential allocation) or increase their reproductive investment when paired with low-quality females (negative differential allocation). This hypothesis has been proposed for monogamous species with biparental care, and most empirical studies focus on birds. Here we used the polygamous spider Paratrechalea ornata, in which males offer prey wrapped in silk as nuptial gifts, to test whether males adjust their reproductive investment in gift size, pre-copulatory and copulatory courtship, and sperm transfer in response to female body condition.ResultsMales exposed to females in good body condition added more flies to the gift, stimulated these females longer with abdominal touches during pre-copulatory courtship, and had longer pedipalp insertions than males exposed to females in poor body condition. Female condition affected neither silk investment in nuptial gift wrapping nor the quantity of sperm transferred by males. Finally, females in good body condition oviposited faster after copulation and laid more eggs than females in poor body condition.ConclusionsWe provide experimental evidence that males of a gift-giving spider exhibit positive differential allocation in three key aspects of their reproductive investment: the size of the nutritious gift, duration of pre-copulatory courtship, and duration of pedipalp insertions, which is regarded as a form of copulatory courtship in spiders. This positive differential allocation is likely associated with the benefits of copulating with females in good body condition. These females are more fecund and oviposit faster after copulation than females in poor body condition, which under natural field conditions probably reduces the risk of multiple matings and thus the level of sperm competition faced by the males. As a final remark, our findings indicate that the hypothesis of differential allocation also applies to species with a scramble competition mating system, in which males heavily invest in nuptial gift construction, but not in parental care.

Benefits of extra food to reproduction depend on maternal condition

The amount of food resources available to upper‐level consumers can show marked variations in time and space, potentially resulting in food limitation. The availability of food resources during reproduction is a key factor modulating variation in reproductive success and life‐history tradeoffs, including patterns of resource allocation to reproduction versus self‐maintenance, ultimately impacting on population dynamics. Food provisioning experiments constitute a popular approach to assess the importance of food limitation for vertebrate reproduction. In this study of a mesopredatory avian species, the lesser kestrel Falco naumanni, we provided extra food to breeding individuals from egg laying to early nestling rearing. Extra food did not significantly affect adult body condition or oxidative status. However, it increased the allocation of resources to flight feathers moult and induced females to lay heavier eggs. Concomitantly, it alleviated the costs of laying heavier eggs for females in poor body condition, and reduced their chances of nest desertion (implying complete reproductive failure). Extra food provisioning improved early nestling growth (body mass and feather development). Moreover, extra food significantly reduced the negative effects of ectoparasites on nestling body mass, while fostering forearm (a flight apparatus trait) growth among highly parasitized nestlings. Our results indicate that lesser kestrels invested the extra food mainly to improve current reproduction, suggesting that population growth in this species can be limited by food availability during the breeding season. In addition, extra food provisioning reduced the costs of the moult–breeding overlap and affected early growth tradeoffs by mitigating detrimental ectoparasite effects on growth and enhancing development of the flight apparatus with high levels of parasitism. Importantly, our findings suggest that maternal condition is a major trait modulating the benefits of extra food to reproduction, whereby such benefits mostly accrue to low‐quality females with poor body condition.

Personality, body condition and breeding experience drive sociality in a facultatively social bird

Adopting different behavioural strategies may reduce within-group conflict, selecting for behavioural consistency (‘personality’). Personality may also affect grouping tendencies. The relationship between the personality dimensions sociability and boldness nevertheless remains unclear. This knowledge gap may reflect a failure to consider potential trade-offs between avoiding conspecifics, potentially alleviating social stress, and avoiding predation. Furthermore, the effects of personality and state (e.g. body condition or age affecting the costs and benefits of behavioural actions) on cooperativeness should be considered together. This is because state may explain predation vulnerability, which may affect boldness under predation risk, and thus antipredator grouping tendencies. To address the problem, we determined how group size preference and group-forming time depended on boldness (flight initiation distance, FID, in response to an approaching human), body condition and breeding experience in facultatively social eiders, Somateria mollissima, where females form coalitions or care for the young solitarily. Breeding adults and young are subject to high predation pressure, providing a strong incentive for brood-tending females to cooperate. Because hormonal differences may also explain differences in sociability, we included baseline and handling-induced serum corticosterone concentrations of incubating females as potential predictors of sociability. We also statistically controlled for availability of potential partners. The relationship between boldness (FID) and the number of coalition partners ranged from negative (females in poor body condition) to positive (females in good body condition), arguing against a uniform relationship between boldness and sociability. The number of coalition partners decreased with female breeding experience. The time taken to form a coalition was shortest close to the hatching peak in the population. Shyness (long FID) delayed group formation. Despite a need for safety in numbers by shy females in poor body condition, their entry into groups may be constrained by their personality, suggesting a possible trade-off between predator and conspecific avoidance.

Integument colouration in relation to persistent organic pollutants and body condition in arctic breeding black-legged kittiwakes (Rissa tridactyla)

Vertebrates cannot synthetize carotenoids de novo but have to acquire them through their diet. In birds, carotenoids are responsible for the yellow to red colouration of many secondary sexual traits. They are also involved in physiological functions such as immunostimulation and immunoregulation. Consequently, carotenoid-based colouration is very often considered as a reliable signal for health and foraging abilities. Although a few studies have suggested that carotenoid-based coloured traits could be sensitive to environmental pollution such as persistent organic pollutants (POPs) contamination, the relationships between pollutants and colouration remain unclear. Here, we examined the relationships between the colouration of carotenoid-based integuments and individual POP levels in pre-laying female black-legged kittiwakes from very high latitudes. In this area, these arctic seabirds are exposed to high POPs contamination. Additionally, we investigated the relationships between colouration and body condition, a frequently used index of individual quality. We found a negative relationship between POP levels and several components of integument colouration: saturation of eye-ring, gapes and tongue, suggesting that POPs could disrupt colouration of labile integuments in female kittiwakes. In addition, we found that females in better body condition displayed more orange and brighter gapes and tongue than females in poor body condition. These results demonstrate that hue and brightness are sensitive to the current health and nutritional status of female kittiwakes. Overall, our study shows that carotenoid-based colour integuments can be affected by several environmental-driven variables.

Lifetime individual plasticity in body condition of a migratory bird

Body condition is an important trait that reflects the capacity of individuals to acquire food or resist disease, eventually allowing successful reproduction and survival. We first quantified the effects of condition on life history and a secondary sexual trait using long-term lifetime data on condition in a migratory bird species, the barn swallow, Hirundo rustica. Second, we quantified sources of individual variation in condition by separating the within-individual from the between-individual components of variation of environmental condition and age on body condition. Therefore, we were able to partition variation as a result of selection and phenotypic plasticity. Within-individual variation in body condition increased in early life until middle age (i.e. 3–4 years of age) in the two sexes followed by only a slight decrease in body condition during senescence in males but not in females. After accounting for age-dependent variation, condition could be partitioned into a within-individual plastic response to environmental conditions during migration and a nonplastic response (i.e. a between-individual difference) to environmental conditions experienced in the African winter quarters. Specifically, there was a within-individual increase in body condition as environmental conditions during migration improved in both males and females, independent of age. There was a between-individual effect of condition found in the winter quarter in body condition of females, but not in males, which was attributed to the disappearance of females in poor body condition from the study population as a result of the higher natal dispersal of low-quality females compared to high-quality ones during years with favourable environmental conditions in the African winter quarters. Males and females also tended to be in better body condition during the warmer springs upon arrival at the breeding grounds. There was a temporal decline in female body condition during 1991–2007, whereas no significant trend was detected in males. Therefore, both intrinsic (e.g. age and sex) and extrinsic factors (e.g. climate) affected body condition.

High levels of organochlorines may affect hatching sex ratio and hatchling body mass in arctic glaucous gulls

Summary 1. Long range transportation via ocean currents and air of various organochlorines (OCs) has resulted in their intrusion in the high Arctic marine food web. At the Spitsbergen archipelago, including Bear Island (Norway), bioaccumulation in top predators like glaucous gulls (Larus hyperboreus) is high, severely affecting their breeding performance and survival. 2. In the present study, we examined the sex ratio of glaucous gull offspring at hatching in relation to the OC blood levels of female parents. Glaucous gulls have male‐biased size dimorphism and females under stress with high levels of OCs are expected to skew the sex ratio towards the less costly female offspring. 3. Our data strongly suggest that among females with low levels of OCs, mothers in good body condition had a hatching sex ratio skewed towards males while those in poor body condition had a skew towards female offspring. However, contrary to expectations, females with high levels of OCs had a strong skew in sex ratio toward male offspring and this was most apparent among females in poor body condition. 4. Hatching body masses of male chicks (controlled for egg size) were negatively related to OC blood level of female parents. There was no such relationship for female offspring. 5. We discuss the skew in hatching sex ratio experienced by OC contaminated glaucous gulls in light of three hypotheses. One is that OC pollutants may mimic hormones and influence the sex determining processes suggested to be under control of steroids. Another is that female transfer of OCs to eggs may increase female embryo mortality. A third hypothesis is that elevated levels of OCs could trigger increased parental investment (terminal investment) which may represent an abortive strategy for OC contaminated gulls, further aggravating the negative impact of OCs on gull population parameters.

Climate predictability and breeding phenology in red deer: timing and synchrony of rutting and calving in Norway and France

Summary Timing and synchrony of reproduction are regarded as crucially important factors for fitness in seasonal environments. Natural selection has probably favoured temperate and arctic female herbivores that match reproduction with onset of plant growth in spring. However, breeding synchrony may also be affected by variation in phenotypic quality of females in a population, because females in poor body condition have been found to delay ovulation and subsequent calving. We compared breeding phenology, i.e. the timing and synchrony of rutting (roaring, sexual aggregation) and calving of red deer (Cervus elaphus L.) in France (latitude: 49°N) and Norway (latitude: 63°N). We hypothesized (H1) that calving and rutting were later at the site with latest onset of plant growth. We further quantified overall environmental predictability as the sum of annual constancy and seasonality and tested three different (not mutually exclusive) hypotheses about breeding synchrony: (H2a) the population experiencing most seasonal plant phenology should show the highest breeding synchrony; (H2b) overall predictability of plant phenology should determine breeding synchrony; and (H2c) breeding should be more synchronized in the population with lowest female body weight variation within age classes because they ovulate more synchronously. Calving and rutting, as well as onset of plant phenology, were later in Norway than in France, complying with the first hypothesis. Plant growth in spring was overall more predictable and also more seasonal in Norway than France. Hence we expected higher breeding synchrony in Norway than in France according to H2a and H2b. Variance in female body weight was slightly higher in France than in Norway, which should also cause more synchronized breeding in Norway than in France (H2c). Contrary to all predictions, variance in rutting and calving dates was around two times higher in Norway than in France. We suggest two alternative explanations of breeding synchrony. A more variable topography in Norway can make optimal birth date more variable on a local scale than in France, thereby maintaining a higher genetic variance for calving date in Norwegian red deer. Further, population age structure may play a role, as ovulation varies according to female age. Clearly, processes of breeding synchrony are far more complex than previously realized.

The effects of age, body weight and reproductive status on conception dates and gestation periods in captive sika deer

Variation in the parturition dates of captive sika deer (Cervus nippon) are explained by factors affecting conception date and gestation period. The timing of conception was related to lactational status, and all non-lactating females conceived before the median conception date. Young females were more likely to conceive after the median date of the conception than older females. Gestation period was not related to the fawn's sex or the female's age. No relationship between gestation period and female body weights was detected in 2000–2001, while an inverse relationship was observed in 1999–2000, a year with heavy snowfall. Conception dates explained most variations in parturition dates in 2000–2001, but gestation periods as well helped explain variations in 1999–2000. We propose that females in poor body condition compensate for poor fetal growth with an extended gestation period after a severe winter. Estimates of conception dates from fetal age or parturition dates should consider these complicating factors.

Interfemale variation in egg yolk androgen allocation in the European starling: do high-quality females invest more?

Androgenic hormones occur naturally in bird egg yolk and are known to enhance growth in canary and gull chicks. Gil et al. (1999, Science, 286, 126–128) have recently proposed that female allocation of androgens to eggs represents a form of costly maternal investment. This hypothesis predicts that females of high quality or high reproductive potential should invest more yolk androgens in their eggs than females of low quality or low reproductive potential. We tested these predictions by examining interfemale variation in allocation of the androgenic steroids testosterone and androstenedione to eggs in a wild population of European starlings, Sturnus vulgaris. We collected 30 full clutches of eggs and captured 22 of the females that laid these clutches for phenotypic measurements. In agreement with the hypothesis, we found that there was significant interfemale variation in yolk androgen concentrations. Furthermore, older females deposited more androstenedione and testosterone in eggs than 1-year-old females, and females laying early or large clutches deposited more testosterone in eggs than females laying late or small clutches. However, females in good body condition did not deposit more androgens in eggs than females in poor body condition. Large-yolked eggs had a higher total yolk androgen content than small-yolked eggs, but larger eggs did not have higher concentrations of yolk androgens. The results in general support the investment hypothesis of yolk androgen allocation. However, further data are needed regarding the costs of yolk androgen allocation and the effects of yolk androgens on offspring to substantiate the assumptions of the hypothesis. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.

Incubation start and egg size in relation to body reserves in the common eider

Avian incubation is often initiated before all eggs are laid. In altricial birds this has been proposed to facilitate brood reduction through asynchronous hatching. However, in precocial birds eggs normally hatch synchronously even if incubation has started before all eggs are laid. Patterns of incubation start may be the adaptive trait selected for both in altricial and precocial species. Several hypotheses have been proposed to explain the timing of incubation start in birds. Decreasing egg-size after incubation start may be adaptively related to an early incubation start, either to ensure synchronous hatching or to decrease fitness cost of late hatched eggs. We have measured individual body condition, egg size and start of incubation in common eider Somateria mollissima, a precocial sea-duck which does not feed during the incubation period. Females in poor body condition start to incubate earlier in the laying sequence than those in good body condition. Furthermore females in poor body condition lay smaller final eggs than females in good body condition. The laying of smaller eggs late in the sequence is therefore probably related to energetic or nutritional state. We propose that females in poor body condition start to incubate early to shorten the nest period in order to reduce their mass loss, but at the cost of reduced size and growth of the ducklings from the eggs laid after incubation start. Females in good body condition on the other hand postpone incubation start at the cost of a longer incubation period and a higher mass loss to the benefit of synchronized hatching and a higher survival of ducklings.

Body Condition and Brood Abandonment in Common Eiders Breeding in the High Arctic

Abstract Post-hatch brood amalgamation is common in many waterfowl species and especially prevalent in the Common Eider (Somateria mollissima). Studies in the temperate region have shown that brood abandonment is influenced both by female body condition and brood size. In this study we tested how these two factors influenced the probability of brood desertion in eiders breeding under harsh conditions in the high Arctic (78N). We found that females in poor body condition were less likely to care for their young, but there was no effects of brood size. We speculate that the differences between southern and northern populations of eiders may be due to different environmental conditions.

Female characteristics and parental care mode in the crèching system of eiders, Somateria mollissima

Eider females may abandon their young, care alone, or join in multifemale crèches. We studied the characteristics of female eiders adopting these strategies in 1996–1999. Female condition at hatching varied significantly between years. Over all years, 31% of all females abandoned, 23% tended alone and 46% crèched. In the year when average female condition at hatching was lowest, abandonment rate peaked (67%). Crèching birds were further identified as true crèchers staying more than 2 weeks with the original crèche, and transient crèchers leaving the crèche. The condition of females shortly before hatching showed a decreasing trend, with lone tenders being in best condition, followed by true crèchers, transient crèchers and abandoners. Clutch size, date of hatching relative to the population median, and female body size did not differ between groups. Individual females switched between care modes between years. Females weighed significantly less when abandoning than when tending, with no significant weight difference when the females remained as tenders between 2 years. This is consistent with the energetic salvage strategy hypothesis, which states that females in poor body condition should be more prone to abandon their brood. Our results support an adaptive approach to offspring care behaviour in eiders, driven by female condition.

Clutch-Size Determination in Precocial Birds: A Study of the Common Eider

-Clutch-size determination in the Common Eider (Somateria mollissima) was evaluated in a colony in northern Norway. Females in good body condition (determined from mass at hatching) produced large clutches and had a shorter incubation period than females with small body reserves. Females in good body condition cared for young (including adoption of the young of other females), while females in poor body condition abandoned their young soon after hatching. Repeatability (an upper limit to heritability) of clutch size, which for individual females varies from three to six eggs, does not differ significantly from zero. A hypothesis is proposed, suggesting that there is a trade-off involved in allocating body reserves to eggs, incubation, and care of chicks and that females use a particular clutch-size strategy related to their body condition and ability to care for young. Received 8 May 1992, accepted 12 May 1993. LACK (1947, 1948) SUGGESTED that clutch size in altrical birds was ultimately limited by the ability of the parents to rear young. Although Lack's hypothesis has been somewhat modified (see Williams 1966, Charnov and Krebs 1974, H0gstedt 1980), the idea of brood-size limitation has been supported by many studies (for reviews, see Klomp 1970, Dijkstra et al. 1990). The adaptive significance of clutch size in birds with self-feeding precocial young is an enigma (Arnold and Rohwer 1991). Clearly, Lack's hypothesis for clutch-size determination in altricial birds cannot apply to precocial birds. A number of other hypotheses have been proposed (see Winkler and Walters 1983). The one most often applied is the egg-production hypothesis (Winkler and Walters 1983, Arnold and Rohwer 1991). This hypothesis was proposed by Lack (1967, 1968), who suggested that clutch size ultimately is limited by the hen's ability to allocate nutrient reserves to egg laying. However, except for studies on arctic-nesting geese (Ankney and MacInnes 1978), evidence corroborating the hypothesis is scarce. A number of studies have shown that female waterfowl use body reserves for egg production (Ankney et al. 1991). However, use of body reserves for egg production has uncritically been used as evidence that available body reserves determine the optimal clutch size (Arnold and Rohwer 1991). Even if nutrient reserves influence number of eggs produced, there may be a trade-off between the use of body reserves for egg production and for later use during incubation (Erikstad 1986, Gloutney and Clark 1991) and care of chicks (Lessells 1986, Bustnes and Erikstad 1991). In this study we examine some of the hypotheses that have been put forth as possible explanations for within-season variation in clutch size. We outline a new hypothesis that combines several earlier ideas to show that clutch-size determination could be affected by an interaction of female body condition, egg predation, and parental care. MATERIALS AND METHODS The study was carried out in a Common Eider (Somateria mollissima) breeding colony near Troms0 in northern Norway (69?49'N, 18?15'E) in 1986-1989. The colony was on a 0.65-km2 island (Grind0ya) and contained 400 breeding pairs. Searches were begun in early May when first nests were initiated. Nests were visited at oneor two-day intervals to determine laying dates and clutch sizes. A clutch was assumed to be complete and incubation to have begun when no new eggs were recorded during a period of three days. We determined intraspecific nest parasitism by detecting multiple eggs laid in a nest within 24 h. The frequency was very low (less than 1%; unpubl. data). All parasitic clutches were excluded from the analysis. Incubation was assumed to begin on the day that the final egg was laid and was completed when one chick had hatched. Females were caught on the nest with a net at hatching and weighed using a spring balance (? 10 g). For a few females caught three to five days before hatching, we estimated hatching mass by using a daily mass