Ejaculate allocation by male sand martins, Riparia riparia.

Males of many species allocate sperm to ejaculates strategically in response to variation in the risk and intensity of sperm competition. The notable exception is passerine birds, in which evidence for strategic allocation is absent. Here we report the results of a study testing for strategic ejaculate allocation in a passerine bird, the sand martin (Riparia riparia). Natural ejaculates were collected from males copulating with a model female. Ejaculates transferred in the presence of a rival male contained significantly more sperm than ejaculates transferred in the absence of a rival male. There was no evidence that this difference was due to the confounding effects of the year of ejaculate collection, the identity of the model female, the colony, the stage of season or the period of the day in which ejaculates were collected. A more detailed examination of the ejaculate patterns of individual males, achieved by the DNA profiling of ejaculates, provided additional evidence for strategic allocation of sperm.     

Sperm length in sand martins Riparia riparia: a comment on Helfenstein et al

How long is a sand martin Riparia riparia spermatozoon? In a recent study, Helfenstein et al. (2008) presented data on the intraspecific variation in sperm length, swimming speed and longevity in this species and some interesting correlations between these variables. However, the reported sperm lengths are remarkably short for the species, which casts doubts about whether sperm total length has actually been measured and how the observed relationships should be interpreted.     

Between‐male variation in sperm size,velocity and longevity in sand martins Riparia riparia

Sperm mobility is known to be an important determinant of a male's sperm competitive ability. Although more debated, sperm length and its relation to sperm swimming ability has also been proposed to determine a male's fertilisation potential. Furthermore, both mobility and length may covary with a male's phenotype, either positively (the phenotype‐linked fertility hypothesis) or negatively if, for instance, low‐quality males have less access to females but invest more in sperm production. Using dummy females, we collected sperm samples from wild sand martins Riparia raparia males. We investigated the relationship between sperm length and sperm swimming speed as measured by sperm straight line velocity (VSL), and determined whether sperm traits are correlated with male body size and condition. We found that total sperm length is repeatable within‐ejaculate and shows substantial inter‐male variation. Sperm length was associated with sperm velocity: males with short sperm have sperm that swim initially faster but die sooner, whereas males with longer sperm have sperm that swim more slowly but for a longer time. Smaller males produced sperm with higher overall velocity. This correlation between male size and sperm behaviour may reflect alternative fertilisation strategies where small males having less mating opportunities invest more in sperm competitive ability. The existence of such alternative strategies would participate in maintaining variation in sperm length and velocity in this species.     

The Influence of Repeated Releases on the Homing Behaviour of Sand Martins (Riparia riparia)

Data on the effect of repeated releases on the homing behaviour of sand martins released four times from the same site (beyond 50 km from the nesting colony) are presented. The results, obtained by two series of releases, show a progressive improvement of both the initial orientation and the homing performances. When the birds released four times from the same site were displaced in a new site, located roughly at the same distance, but in the opposite direction to the former, they do not change directional preferences with respect to the last experimental release; the homing speeds were also not different to those recorded for birds without any release experience. While the learning of orienting cues can not be excluded, the data point out that the habituation to the handling stress and a form of directional training seem to play a major role in determining the observed behaviour. The familiarity with a site does not seem to improve the homing behaviour of sand martins when released from a different one.     

Energetics of free existence in swallows and martins (hirundinidae) during breeding: a comparative study using doubly labeled water

Energy metabolism of three sympatric swallows (Hirundinidae) was investigated during the breeding season using doubly labeled water (²H₂¹⁸O). Interspecific and intraspecific differences in energy metabolism were examined in relation to the habits, size and environment of the birds. To facilitate comparisons we expressed energy metabolism (M) as the ratio of average daily metabolic rate (ADMR, cm³CO_2g^-1h^-1) to basal metabolic rate (BMR). We observed adults during incubation and when feeding nestlings. Then, both sexes of Sand Martins Riparia riparia and House Martins Delinchon urbica were either at the nest or on the wing. Incubation reduced activity levels during the day resulting in M (incubation) being 17–26% lower than during rearing. Differences in energy costs for rearing chicks depended mainly on flight behaviour, the smaller Sand Martin doing nearly twice as much flapping during flight as the House Martin, giving higher values for M. In Swallows Hirundo rustica the female incubates alone, alternating between short feeding trips and incubating in daytime. This pattern was linked with a relatively high value for M in the only individual behaving like our controls. Both sexes of Swallows feed the chicks, and they showed similar values of M. They also closely resembled House Martins, despite contrasts in the time spent flying and their behaviour during flight. Feeding conditions affected activity, and thereby M, in a species specific way. The House Martin did more gliding in poor weather, taking less mobile prey, reducing M. Swallows reduced foraging costs further by using body reserves, as in the House Martin. The smaller Sand Martin, in contrast, showed a high expenditure in poor weather. Over two breeding seasons ADMR reached values around 5 BMR for all three species.     

Body condition is associated with a shorter breeding season and reduced ovulation rate in subtropical goats

To determine the effect of body condition on the characteristics of the breeding season in female goats from subtropical Mexico, does in either greater- or lesser-body condition (n=20/group) were monitored for the expression of estrous behavior, ovulation and ovulation rate between June and April. The commencement of estrus and ovulation occurred earlier (P<0.05) in does in greater than lesser body condition. The cessation of estrus and ovulation was later (P<0.05) in female goats with greater than those with lesser body condition. Does in greater body condition had more (P<0.001) normal estrous cycles than those in lesser body condition. As consequence, does from the greater body condition group had fewer short (P<0.001) or long (P<0.05) estrous cycles than those of in the lesser body condition group. The ovulation rate was greater (P<0.01) in the greater (1.9+/-0.1) than lesser body condition does (1.6+/-0.1). In conclusion, female goats in lesser body condition have a shorter breeding season, more abnormal estrous cycles, and fewer ovulations than does in greater body condition.     

No evidence of genetic benefits from extra-pair fertilisations in female sand martins (Riparia riparia)

Genetic parentage studies of socially monogamous birds reveal a widespread prevalence of extra-pair paternity. Variation in extra-pair paternity among individuals may depend on how different individuals benefit from extra-pair fertilisations and on the opportunity to pursue extra-pair copulations. A long-term study of sand martins (Riparia riparia) in Hungary allowed us to examine patterns of extra-pair fertilisations in a large colony of over 3,000 breeding pairs with many known age individuals. We used multi-locus DNA fingerprinting to determine whether extra-pair fertilisations occur when females are paired to (1) presumably low quality mates, or (2) genetically similar or dissimilar mates, and whether extra-pair fertilisations result in offspring of higher quality. Extra-paternal young were found in 38% of 47 broods and comprised 19% of 190 offspring. Males that lost paternity did not differ significantly from others in age or body condition. Social mates of broods containing extra-pair offspring did not differ in genetic similarity from pairs without extra-pair offspring. Furthermore, there was no significant difference in body condition between extra-pair young and their maternal half-siblings. We were unable to assign paternity and therefore cannot exclude the possibility that extra-pair males differed from the within-pair males they cuckolded, in age, body condition or genetic similarity with the female. We found a positive relationship between paternity losses and breeding density, suggesting that low breeding density may constrain opportunities for seeking extra-pair copulations.     

Body condition and ruminal morphology responses of free-ranging impala (Aepyceros melampus) to changes in diet

Variation of the intraruminal papillation pattern with diet quality has been described in many ruminant species, but the use of papillation measures as a proxy for habitat quality and nutritional status of animals has not been evaluated. We compared various measures of body condition (body mass, body condition score, kidney fat index, bone marrow fat index, adrenal mass, kidney to adrenal mass ratio), diet quality (%browse, protein and fibre content) and rumen papillation in 106 impalas (Aepyceros melampus) from four different locations in Zimbabwe. The various condition proxies indicated that periods of low diet quality are characterised by a high proportion of browse in the diet of this species. Animals with a high proportion of browse had more voluminous rumens, suggesting a compensation for lower diet quality by increased intake. Macroscopic papillation indices did not yield meaningful significant correlations with diet quality or body condition proxies, and hence, their use for estimating habitat or body condition cannot be advocated. In contrast to previous histological reports, ballooning cells of the Stratum corneum of the ruminal mucosa were more prominent in animals on lower-quality diets. There were significant correlations of the kidney to adrenal mass ratio with other body conditions and with diet quality indices, suggesting that poor body condition and low diet quality represent stressful situations.     

Metabolic changes in male snakes, Thamnophis melanogaster, during a breeding period

1. Daily basking periods were lengthened substantially during a breeding period in a natural population of the snake, Thamnophis melanogaster. 2. In the laboratory, oxygen consumption of male T. melanogaster significantly increased during a breeding period, compared to pre- and post-breeding levels in the same males. 3. In both laboratory and field males, serum lipid increased initially and then decreased during the breeding period. 4. Serum protein of laboratory males decreased significantly following the breeding period. 5. Serum glucose did not change significantly in laboratory males, but increased significantly during the breeding period in field males. 6. Changes in oxygen consumption and nutrient distribution may reflect changing energy demands attendant with gonadal recrudescence in this snake.     

Body mass changes in Brünnich's guillemots Uria lomvia with age and breeding stage

Body mass of Brünnich's guillemots Uria lomvia breeding at Coats Island, Canada, was measured during incubation and chick‐rearing in 1988–2001. In most years, mass increased during incubation and fell after hatching, leveling off by the time chicks were 18 d old, close to the age at which chicks departed. Mass during incubation increased with age up to about 12 yr, but the mass of birds brooding chicks was not related to age. The trend towards increasing mass during incubation was mainly a consequence of mass increases of young breeders as older birds maintained a constant mass. The variation in adult mass with age during incubation seems likely to reflect age‐related variation in foraging ability, but the loss of mass after hatching, being greater for older birds, appears best explained as a response to the demands of provisioning chicks, with older birds transferring their accumulated reserves to their chicks via higher provisioning rates.     

European starlings: nestling condition, parasites and green nest material during the breeding season

Male European starlings (Sturnus vulgaris) intermingle fresh herbs, preferably species rich in volatile compounds, into their dry nest material. In a field study, we investigated whether these herbs affect the mite and bacteria load of the nests and the condition of the nestlings either directly or via parasite control. We examined the amount of herbs and the number of plant species males carried into their nests, the variation of volatile compounds in the headspace air of the nest boxes and mite/bacteria load of the nests throughout the season. The amount of herb material and the number of plant species, the number of substances emanated by these plants and the infestation of the nests with bacteria and mites (Dermanyssus gallinae) increased with season. In a field experiment, we exchanged natural starling nests with experimental nests with or without herbs. We found that the herbs had no effect on the mites but fewer bacteria were sampled in nests with herbs than in nests without herbs. The body mass of the fledging was not related to the season or the mite/bacteria load of the nests. However, nestlings from nests with herbs fledged with higher body mass than nestlings from nests without herbs. Both bacteria and mite load were related to nestling mortality. In nests containing no herbs, the numbers of fledglings declined significantly with the increasing mite load while the mites had no effect on the number of fledglings in nests with herbs. Thus, the nest herbs counteracted the effect of the mites. In conclusion, it seems that volatile herbs can reduce bacterial but not mite infestation of the starling nests. The positive influence of herbs on nestling growth indicates that herbs either directly (perhaps as immunostimulants) improve the condition of the nestlings and help them cope with the harmful effects of mites, or they provide a nest environment beneficial for the nestlings‘ development by the reduction of germs.     

Correlating context-specific boldness and physiological condition of female sand fiddler crabs (Uca pugilator)

Consistent individual behavioral differences across ecological contexts are a recognized feature of animal populations. These differences can be expressed in two ways: context-specifically or context-generally. The former is characterized by consistent responses in one context (i.e. repeatability), whereas the latter by consistency that spans contexts (i.e. behavioral syndromes). The proximate causes of behavioral consistency remain unclear, yet there is evidence that physiology may couple the expression of some behavioral traits in unrelated contexts. We therefore explored the correlation between bold behavior of female sand fiddler crabs (Uca pugilator) and the condition of the hepatopancreas, an organ vital to crustacean metabolism and reproduction. We did this by taking replicate measurements of two risk-taking behaviors per individual in the contexts of predator avoidance and environment exploration, and examining correlations within and between these observations. We then determined the relationship of behavior with hepatopancreas mass and lipid content. Individual crabs responded consistently within each context. However, across-context correlations were absent, indicating that boldness is isolated, at least in the selected scenarios. Additionally, anti-predator and exploratory behaviors were significantly influenced by size but not linked to hepatopancreas physiology. Our results show that context-specific trait expression may occur in the absence of a physiological correlate.     

Body mass changes inTrimeresurus flavoviridis (Viperidae) on Okinawa Island,Japan

Body masses of wild-caught habu,Trimeresurus flavoviridis, were measured with known error range. Habu larger than mature female size had steeper slope in length-mass regression than smaller individuals. Females outweighed males in most snout-ventlength classes and in early summer. Gravid females outweighed non-gravid ones by about 20% on the average, but the body mass ranges of the two groups overlapped. Through the body mass change in mature females, the proportion of gravid females was estimated to be about 0.5.     

Structural changes in light- and dark-adapted compound eyes of the australian earwig Labidura riparia truncata (dermaptera)

The apposition acone eye of Labidura is relatively small—550–600 facets—with a thick corneal lens and shallow retina. The retinula cell columns are each formed of six peripheral cells plus two central cells, a partially fused rhabdom, and dense pigment in two or three cell types. Upon adaptation from light to dark, the most striking photomechanical response is a proximal broadening of the cone cells, which results in a 38-fold increase in cross-sectional area of the aperture. While longitudinal rhabdom movement is small, microvillar diameters swell in response to light and contract in the dark. Irregularities of facet pattern and shape, and in ommatidial alignment were found, particularly towards eye margins. Three types of interommatidial sense organs on the eye surface are described, one of which has not been previously reported. An argument is presented to explain how the field of view and sensitivity are both apparently decreased in the acone eye by exposure to light.     

Variation of cleavage pattern permitting normal development in a sand dollar,Peronella japonica: comparison with other sand dollars

 Peronella japonica, a sand dollar, forms an abbreviated pluteus larva and metamorphoses within 3 days without feeding. In the present study, the cleavage pattern of Peronella embryos was found to be quite irregular in the vegetal blastomeres at the fourth cleavage. Less than half of the embryos examined formed four typical micromeres. The majority formed zero, one, two or three typical micromeres of regular size, and the blastomere(s) remaining in the vegetal-most region was atypical in size and/or its direction of division. Most embryos were able to form pluteus larvae and a considerable proportion of these metamorphosed into juvenile sea urchins, regardless of whether or not they had formed four typical micromeres of regular size, although embryos which formed no typical micromeres developed into pluteus larvae less frequently. The micromere progeny in Peronella embryos form skeletogenic mesenchyme cells. The average numbers of skeletogenic mesenchyme cells in the three sand dollar species, Clypeaster japonicus, Astriclypeus manni and P. japonica were 62, 122 and 219, respectively. In these species, the skeletogenic mesenchyme cell-specific glycoprotein (msp130) was first detected immediately after ingression of the primary mesenchyme cells, spicules appeared at the early gastrula stage and triradiate spicules were found in late gastrulae. Appearance of these characteristics was markedly accelerated in the embryos of A. manni and P. japonica in comparison with those of C. japonicus. Each step in the formation of larval spicules was equally accelerated in A. manni and P. japonica, although the appearance of the adult skeleton was further accelerated in P. japonica in comparison with A. manni, possibly because of omission of the four- to eight-armed pluteus stages. Received: 1 September 1995 / Accepted in revised form: 21 May 1995     

A comparison of seed banks across a sand dune successional gradient at Lake Michigan dunes (Indiana,USA)

In habitats where disturbance is frequent, seed banks are important for the regeneration of vegetation. Sand dune systems are dynamic habitats in which sand movement provides intermittent disturbance. As succession proceeds from bare sand to forest, the disturbance decreases. At Indiana Dunes National Lakeshore, we examined the seed banks of three habitat types across a successional gradient: foredunes, secondary dunes, and oak savanna. There were differences among the types of species that germinated from each of the habitats. The mean seed bank density increased across the successional gradient by habitat, from 376 to 433 to 968 seeds m⁻², but with foredune and secondary dune seed bank densities being significantly lower than the savanna seed bank density. The number of seeds germinated was significantly correlated with soil organic carbon, demonstrating for this primary successional sequence that seed density increases with stage and age. The seed bank had much lower species richness than that of the aboveground vegetation across all habitats. Among sites within a habitat type, the similarity of species germinated from the seed banks was very low, illustrating the variability of the seed bank even in similar habitat types. These results suggest that restoration of these habitats cannot rely on seed banks alone.     

Body condition of Little Egret Egretta garzetta nestlings in relation to hatching order in a southern Tunisian breeding colony

The effect of asynchronous hatching on nestling health and condition in ardeids is still in need of empirical evidence from populations living in different environmental conditions. Using morphometric and hematologic data from Little Egret Egretta garzetta nestlings in a Tunisian breeding colony, we assessed the relationship between hatching order and nestling condition, while accounting for the effects of brood size, age and hatching date. Our results showed that the youngest nestlings had lower values of hematocrit and body condition index but higher levels of fluctuating asymmetry compared with their older siblings. These trends seem to stem from increased nutritional stress experienced by younger nestlings who would have received less food from their parents than their siblings due to their less competitive nature. Additional constraints during the rearing period, such as possible injuries resulting from conflicts with siblings and the energy cost of thermoregulation, may also have contributed to the deterioration of the condition of last nestlings. Overall, our findings provide empirical evidence of the short-term repercussions of asynchronous hatching in a North African population of Little Egrets. They also highlight the great complexity of mechanisms by which asynchronous hatching may affect body condition and health of bird nestlings.     

Body condition dynamics and the cost‐of‐delay hypothesis in a temperate‐breeding duck

Pre‐breeding body condition is an important determinant of reproductive success in birds, largely through its influence on timing of breeding. Declines in clutch size and recruitment probability within breeding seasons indicate a tradeoff may exist between the number of young (clutch size) and quality of young (recruitment probability). We explored local drivers of pre‐breeding body condition and tested predictions of the cost‐of‐delay hypothesis in female lesser scaup Aythya affinis. Yearling females arrived on the study site in lower body condition than older females, but both age classes had similar rates of body condition gain on the breeding grounds prior to nesting. Rates of body condition gain were positively influenced by water temperature, a proxy for wetland phenology. The effect of water level was asymptotic and interacted with water temperature, with greater rates of gain in body condition occurring in years with low water levels. Our results supported the predicted response of clutch size to the rate of pre‐breeding body condition gain. After accounting for lay date, clutch size was positively related to the rate of body condition gain (= 0.08 ± 0.039). We did not find support for a predicted interaction between rate of body condition gain and intra‐seasonal decline in clutch size (= 0.01 ± 0.01). Our results indicate that local conditions during pre‐breeding influence body condition dynamics in female lesser scaup, which subsequently affects clutch size.