bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of optimal microwave curing cycle for fly ash mortars
Authors: Topçu İlker Bekir , Toprak Mehmet Uğur , Akdağ Devrim
Published: April 2008

Microwave energy can accelerate the hydration of cement, which results in the rapid strength development of concrete. In this paper, prediction of later age compressive strength of fly ash cement mortars, based on the accelerated strength of mortars cured with microwave energy, was investigated. To accelerate curing properly, optimal processing parameters of microwave curing (MC) on Portland cement mortars (CM) and fly ash cement mortars (FA) were first determined and then were applied to mortars. The possible early ages for the strength prediction were found to be at 6 and 8 h for CM and FA, respectively. The error percentages for prediction of CM were ±2.22% and 2.91% for 7 and 28 d, respectively. Error percentages for FA, on the other hand, were ±4.36% and 5.20% for 7 and 28 d, respectively.
Application of lean thinking to improve the productivity of water and sewer service installations
Authors: Kung Dale , Alex Dinu Philip , Al-Hussein Mohamed , Fernando Siri
Published: April 2008

The installation of water and sewer services is an essential element of many construction projects. With an increasing number of construction projects being undertaken in metropolitan areas, delays are no longer affordable. To increase productivity in this type of construction project, workflow must be improved. This paper describes the application of lean thinking principles to improve the productivity of water and sewer service installations. To illustrate this, a case study is presented that applies these principles to water and sewer service installations performed by City of Edmonton construction crews. As well, this paper outlines a study that applies the lean thinking procedures recommended within a queuing theory model to validate the effect of the proposed improvements to productivity. Potential improvements to overall productivity will be discussed along with proposed future research.
First-winter survival of rainbow trout and brook trout in the Henrys Fork of the Snake River, Idaho
Authors: Meyer Kevin A. , Griffith J. S.
Published: April 2008

We used caged fish with a cobble – boulder substrate to test the effect of fish size on first-winter survival of rainbow trout, Oncorhynchus mykiss, to compare survival of rainbow trout and brook trout, Salvelinus fontinalis, and to test for a temperature effect in each experiment. At the warmer site, over 90% of the rainbow trout in the size experiment survived the winter, and there was no significant difference between >90 and <90 mm fish. At the colder site, survival was 60% and all mortality occurred in fish <90 mm. Survival of brook trout (60%) was significantly less than that of rainbow trout (87%) but did not differ between the warmer and colder sites. Brook trout that survived were significantly larger than those that did not. Results suggest that size-dependent mortality may be more likely to occur when environmental conditions are more severe (e.g., lower temperatures, less suitable habitat). Rainbow trout experienced less mortality than brook trout when using cobble – boulder substrate as cover during their first winter; this may be the result of different winter-habitat preferences between the two species.
Estimating metabolic costs for homeotherms from weather data and morphology: an example using calidridine sandpipers
Authors: Cartar Ralph V. , Morrison R. I. Guy
Published: April 2008

It is often desirable to estimate the metabolic costs incurred by homeothermic organisms of differing morphology living in different real or hypothetical environmental conditions. To address this problem, we describe a method, based on previously published empirical allometric and heat-transfer equations, that allows a rough estimate to be made of the daily maintenance metabolic costs (i.e., basal and thermoregulatory costs) incurred by a bird in a simple cold two-dimensional environment. The model uses widely available weather variables (temperature, wind speed, and global solar radiation), morphological variables (body mass, height of body's centre of gravity, diameter of torso), and a habitat variable (height of vegetation). We apply the model to weather data from the Canadian Arctic to predict daily metabolic costs for two calidridine sandpiper species (Calidris canutus and C. minutilla) during the summer. The model is extremely sensitive to error in the slope and intercept of the allometric equation predicting conductance from body mass, but is generally robust to other model parameters. Using ambient temperature (Ta) in place of operative temperature (Te) has only a minor (3.5%) effect on predicted metabolic costs, so, given that Teis difficult to estimate, we recommend this substitution (at least for arctic latitudes, where solar radiation is of reduced importance). The model predicts metabolic rates similar to those obtained from an equation based on a heated taxidermic mount for C. canutus, thereby providing some measure of validation. The model can easily be modified to predict metabolic costs for other groups of birds or mammals.
The influence of structural clutter on activity patterns of insectivorous bats
Authors: Brigham R. M. , Grindal S. D. , Firman M. C. , Morissette J. L.
Published: April 2008

We experimentally tested the hypothesis that three-dimensional structural clutter is a major factor affecting habitat choice by insectivorous bats. To do this we artificially increased clutter at two sites used by bats without affecting prey availability. Our measure of available insect prey did not differ between treatment and control sites, indicating that only the spatial complexity of the habitat type was manipulated. Artificial clutter negatively affected foraging activity by small bats (Myotis spp.), supporting the hypothesis that physical clutter does affect foraging by bats. In direct contrast to our expectation, large bats (Eptesicus fuscus, Lasiurus cinereus, Lasionycteris noctivagans) were apparently unaffected by the clutter treatment. We suggest that this may be an artifact of our experimental design, because our ultrasonic detectors probably recorded large bats flying above the artificial clutter.
Allometry of diving capacity in air-breathing vertebrates
Authors: Schreer Jason F. , Kovacs Kit M.
Published: April 2008

Maximum diving depths and durations were examined in relation to body mass for birds, marine mammals, and marine turtles. There were strong allometric relationships between these parameters (log10transformed) among air-breathing vertebrates (r = 0.71, n = 111 for depth; r = 0.84, n = 121 for duration), although there was considerable scatter around the regression lines. Many of the smaller taxonomic groups also had a strong allometric relationship between diving capacity (maximum depth and duration) and body mass. Notable exceptions were mysticete cetaceans and diving/flying birds, which displayed no relationship between maximum diving depth and body mass, and otariid seals, which showed no relationship between maximum diving depth or duration and body mass. Within the diving/flying bird group, only alcids showed a significant relationship (r = 0.81, n = 9 for depth). The diving capacities of penguins had the highest correlations with body mass (r = 0.81, n = 11 for depth; r = 0.93, n = 9 for duration), followed by those of odontocete cetaceans (r = 0.75, n = 21 for depth; r = 0.84, n = 22 for duration) and phocid seals (r = 0.70, n = 15 for depth; r = 0.59, n = 16 for duration). Mysticete cetaceans showed a strong relationship between maximum duration and body mass (r = 0.84, n = 9). Comparisons across the various groups indicated that alcids, penguins, and phocids are all exceptional divers relative to their masses and that mysticete cetaceans dive to shallower depths and for shorter periods than would be predicted from their size. Differences among groups, as well as the lack of relationships within some groups, could often be explained by factors such as the various ecological feeding niches these groups exploit, or by variations in the methods used to record their behavior.
Timing of reproduction in wild mink: the influence of spawning Pacific salmon
Authors: Ben-David M.
Published: April 2008

In many species of seasonally breeding mammals, reproduction occurs later at higher latitudes. Records of timing of reproduction in free-ranging American mink (Mustela vison) in North America and Europe suggest a similar trend. Observations on mink in southeast Alaska, however, revealed a deviation from this pattern, suggesting that factors other than latitude and associated day length may affect timing of breeding for this species in this area. I investigated timing of reproduction and body condition of wild, free-ranging mink on Chichagof Island, southeast Alaska, and hypothesized that seasonal food availability, especially abundant carcasses of spawning Pacific salmon (Onchorhynchus sp.), would determine timing of breeding in this population of mink. Blood progesterone levels, body condition, and testicle lengths were recorded for 24 adult mink, livetrapped from mid-March to late July in 1992 and 1993. Results suggest that these free-ranging mink mate during the later part of April to early May, and parturition occurs in late June to early July. Although male mink seemed to respond to photoperiodism in initiating reproduction, timing of reproduction in female mink was shifted so that lactation coincided with the availability of carcasses of Pacific salmon.
The buccal capsule of Aduncospiculum halicti (Nemata: Diplogasterina): an ultrastructural and molecular phylogenetic study
Authors: Baldwin J. G. , Eddleman C. D. , Giblin-Davis R. M. , Williams D. S. , Vida J. T. , Thomas W. K.
Published: April 2008

The buccal capsule of Aduncospiculum halicti (Diplogasterina) is compared with that of Zeldia punctata (Cephalobina) and Caenorhabditis elegans (Rhabditina). Characters are mapped on an independent DNA-based phylogenetic tree (inferred from RNA polymerase II and rDNA sequences) to test evolutionary hypotheses. Irrespective of dimorphism, the buccal capsule wall of A. halicti consists of an anterior to posterior series of six cuticular structures classically termed rhabdions. These are defined according to their internal differentiations, discontinuities in profiles, and underlying tissues. Homologies of rhabdions 1 and 2 in A. halicti are proposed on the basis of position and association with adjacent tissues, consistent with those of Cephalobina and Rhabditina. Rhabdion 3 is associated with radial epithelial cells as is the mesorhabdion in C. elegans; this contrasts with Z. punctata, where a rhabdion in a similar position is associated with radial muscle cells. Dorsal and subventral teeth in A. halicti comprise rhabdions 4 and 5; this may be homologous with a corresponding region in Z. punctata but contrasts with C. elegans, where the corresponding region consists of a single metarhabdion. These characters, when mapped on the sequence-based tree, suggest that A. halicti and Diplogasterina share with C. elegans and other Rhabditina derived characters, including a mesorhabdion associated with epithelial cells, but retain some apparently primitive features shared with Cephalobina.
Effects of reproduction on survival and growth of female northern water snakes, Nerodia sipedon
Authors: Brown Gregory P. , Weatherhead Patrick J.
Published: April 2008

The cornerstone of life-history theory is the expectation that current reproduction will have a detrimental effect on survival and (or) future reproduction. When fecundity increases with body size, the cost to future reproduction arises through decreased growth of reproductive individuals. We investigated the effects of reproduction on aspects of survival and growth in female northern water snakes (Nerodia sipedon). We did not find a decrease in survival associated with mating despite the conspicuousness of mating aggregations, and pregnancy did not impair locomotor ability. We found evidence of a decrease in over-winter survival of reproductive females related to their emaciated state following parturition. Reproductive females grew less in length than nonreproductive females, but increased similarly in mass. Following parturition, reproductive females weighed less than in the spring, indicating that mass gain prior to parturition was invested in the litter and that most foraging occurred prior to ovulation. Captive reproductive females given food ad libitum grew in length at a rate similar to free-living reproductive females, but increased more in mass. Captive females weighed more after giving birth than in the spring, indicating that unlike that of females in the wild, some of their mass increase was due to energy storage, and also that they continued to feed after ovulation. Consistent with the prediction that smaller females would benefit more than larger females from reproducing less and growing more to increase future fecundity, we found that smaller females participated less in mating aggregations and reproduced less often.
Histology and histochemistry of androgen-stimulated nuptial pads in the leopard frog, Rana pipiens, with notes on nuptial gland evolution
Authors: Epstein M. S. , Blackburn D. G.
Published: April 2008

Nuptial pads are digital specializations of male frogs that cycle with the reproductive season and are considered to function in mating. Glandular secretions of the nuptial pads were analyzed histochemically in androgen-stimulated overwintering leopard frogs, Rana pipiens, to provide information on gland function and physiological control. In castrated and sham-operated male frogs treated with testosterone cypionate, the secretory product of the nuptial gland epithelium stained positive for carbohydrates and proteins, yet negative for lipids and glycogen. Secretions also stained positive for tyrosine residues and negative for acidic mucosubstances, sulphated mucosubstances, tryptophan, and cystine. Castration prior to hormone treatment had no effect on gland staining properties, and glands of cholesterol-treated castrates and intact controls appeared to be inactive cytochemically. Nuptial glands of frogs treated with 5-α-dihydrotestosterone were histologically similar to those of frogs treated with testosterone cypionate. Nuptial glands share structural and functional characteristics with integumentary mucous glands, and may have been modified evolutionary from that parent gland population.
Seasonal food habits of bobcats (Lynx rufus) in subtropical Baja California Sur, Mexico
Authors: Delibes M. , Zapata S. C. , Blázquez M. C. , Rodríguez-Estrella R.
Published: April 2008

The annual and seasonal diet of the bobcat (Lynx rufus) was determined from analysis of 188 feces in the Cape region of Baja California, Mexico, an arid zone with numerous subtropical elements in its flora and fauna. Bobcats fed mainly on lagomorphs, which reached 74% of occurrence, followed by rodents (40%), reptiles (15%), and birds (12%). No seasonal variations were observed. The results were consistent with those of studies elsewhere, indicating that bobcats still rely upon lagomorphs for much of their food in southern latitudes. This supports the hypothesis that lynx have evolved to prey on hares and rabbits. The prevalence of reptiles as prey of bobcats in our study area was the highest ever reported. They were reported as bobcat prey in only 1 of 20 studies from north of latitude 40°, but in 14 of the 18 studies carried out south of this latitude. With regard to feeding on reptiles, the habits of bobcats in Baja California Sur resemble those of other similar-sized felids in tropical areas, such as ocelots (Felis pardalis) and servals (Leptailurus serval).
Stomach oil and reproductive energetics in Antarctic prions,Pachyptila desolata
Authors: Taylor Jan R. E. , Place Allen R. , Roby Daniel D.
Published: April 2008

We studied energy-provisioning rates and energy requirements of nestlings, as well as energy-expenditure rates of adults in Antarctic prions (Pachyptila desolata) on sub-Antarctic Bird Island, South Georgia. Special emphasis was placed on investigating the role of stomach oil as an energy source for nestlings. Nestlings were periodically weighed overnight (n = 91 nestling-nights, 5 nights), and the mass of food consumed by nestlings was estimated from the sum of positive mass increments recorded over 3-h intervals. Prion nestlings consumed, on average, 36.6 g food per day at the age of peak body mass. The probability of each parent feeding its nestling overnight was 0.57, but feeding frequency varied significantly among nights. The median volume of stomach oil in proventriculi of nestlings was 0.9 mL (n = 44), and was negatively correlated with nestling age. Prion nestlings had a relatively high conversion efficiency of food mass to body mass (0.615), indicating a high energy density of nestling meals. Nestling energy budgets revealed that nestling energy requirements could not be met unless a portion of the food mass delivered by the parents consisted of stomach oil. We conclude that Antarctic prions represent an intermediate position in the spectrum of procellariiform dependency on stomach oil during nestling rearing, with diving petrels (which do not produce stomach oil) at one extreme and storm-petrels at the other. Field metabolic rates of adults feeding nestlings, measured by means of the doubly labeled water technique, averaged 4.16 mL CO2/(g∙h), or 391 kJ/day. We suggest that this relatively low metabolic rate while foraging at sea is important for stomach oil formation, as it permits adults to allocate a greater proportion of energy from ingested food to their young.
Histology of the grooved ventral pouch of the minke whale,Balaenoptera acutorostrata, with special reference to the occurrence of lamellated corpuscles
Authors: Bakker M. A. G. de , Dubbeldam J. L. , Kastelein R. A.
Published: April 2008

The rorquals, Balaenopteridae, catch their food by swimming into a concentration of krill or schooling fish, taking up prey-laden water, and then filtering it with their fringed baleen. An anatomical feature adapted to this feeding strategy is the expansible buccal cavity. The amount of expansion depends upon the elasticity of the grooved ventral pouch forming the wall of the buccal cavity. This wall consists, in addition to the fat tissue, of thick layers of elastic connective tissue and muscle. In these layers, lamellated corpuscles were found close to the grooves. These sense organs may play a role in the timing of mouth closure during feeding.
Postweaning behaviour in pups of the southern elephant seal (Mirounga leonina) on South Georgia
Authors: Modig Anders , Engström Henri , Arnbom Tom
Published: April 2008

After weaning, southern elephant seal pups (Mirounga leonina) fast for 3 – 8 weeks, for largely unknown reasons. During the postweaning fast we observed daytime behaviour and movements of pups on South Georgia in relation to mass, sex, and tooth eruption. There was variation in behaviour, with the lowest levels of activity from about 09:00 to 15:00. When ashore, weaned pups spent 97% of the time resting. There was no difference in activity between the sexes, except that only male pups were observed fighting. There was a significant difference in tooth eruption between the sexes. In female pups, 87.9% had teeth at weaning, while only 28.7% of male pups had. There was no correlation between mass at weaning and activity in either sex. Weaned pups tended to gather in groups (median group size 3, range 2 – 67). Several factors may affect the behaviour of pups during the postweaning fast: the resting behaviour required to save energy favours spending time ashore during the day (which also enhances vitamin D synthesis), and foraging is more effectively practiced at night because their prey is more active at night.
The effect of parasites on courtship dance in threespine sticklebacks: more than meets the eye?
Authors: Brønseth Torfinn , Folstad Ivar
Published: April 2008

Hamilton and Zuk proposed that elaborate male secondary sexual characters have evolved through female choice because they reveal information about heritable resistance against parasites. The courtship dance of the threespine stickleback (Gasterosteus aculeatus) is a secondary sexual character that has previously been suggested to be of minor importance for female choice. We relate phenotypic condition and intensities of naturally acquired parasites of male threespine sticklebacks to the size of an important morphological structure used for movements in this species, the pectoral fin. Fin size is sexually dimorphic and is closely related to a male's condition factor. We show that, contrary to Hamilton and Zuk's original prediction, there is a positive relationship between the secondary sex trait and the intensity of prevalent parasites. We argue that the results nonetheless support the underlying assumption in Hamilton and Zuk's hypothesis, as fin size can be indicative of an individual's ability to tolerate the costs of increased parasite exposure and susceptibility. It is suggested that the courtship dance may act as an amplifier of the size of the transparent fins and consequently reveal information about male condition and parasite resistance to mate-searching females.
Variation in the mitochondrial DNA of theSylvilaguscomplex occupying the northeastern United States
Authors: Litvaitis Marianne K. , Lee Woo-Jai , Litvaitis John A. , Kocher Thomas D.
Published: April 2008

We compared the variation in mitochondrial DNA among species of cottontail rabbits in the northeastern United States to (i) assess the effects of historic transplants of eastern cottontails (Sylvilagus floridanus) on subspecific status, (ii) examine the extent of hybridization between invading eastern cottontails and declining populations of endemic New England cottontails (S. transitionalis), and (iii) evaluate the recent reclassification of S. transitionalis into two sister-species, New England cottontail and Appalachian cottontail (S. obscurus). Sequence variation in the tRNAProand the first 310 base pairs of the control region supported a separation of the two species S. floridanus and S. transitionalis/S. obscurus. However, geographic structuring of haplotypes was not detected for either group. Genetic similarity among populations of S. floridanus indicated that subspecific designations are not warranted for this species in the northeastern United States. Comparisons of sequence information from populations of S. transitionalis/S. obscurus that were never sympatric (Maine), recently sympatric (New Hampshire), or sympatric with eastern cottontails since the last glaciation of eastern North America (Virginia, West Virginia, Maryland, North Carolina) indicated that hybridization is not occurring between eastern cottontails and New England or Appalachian cottontails. Limited variation in mitochondrial DNA does not support the recent reclassification of S. transitionalis into sister-species. However, karyotypic and morphological differences between northern and southern populations should be considered during any efforts to restore declining populations of this species.
Patterns of growth and physical maturity in the western Mediterranean striped dolphin, Stenella coeruleoalba (Cetacea: Odontoceti)
Authors: Calzada Nuria , Aguilar Alex , Grau Esteve , Lockyer Christina
Published: April 2008

The growth and physical maturation of striped dolphins (Stenella coeruleoalba) of the northern section of the western Mediterranean Sea were studied. Fitted Gompertz growth curves indicate that females grow faster than males when they are young, but their growth ceases and the asymptotic length is attained earlier than in males. Asymptotic length was greater in males (200 cm) than in females (194 cm). Males reached vertebral physical maturity at 15–20 years old and females earlier, at 13–18 years old. Cranial maturity was apparently achieved at similar ages and body lengths. The radius and ulna, however, completed their ossification much earlier, again showing sexual dimorphism, with females maturing at a younger age (5–6 years) and smaller body length (160–175 cm) than males (8–9 years and 170–181 cm). Age-related parameters of physical maturation and growth determined for this population were similar to those estimated for the striped dolphins inhabiting Japanese waters, while length-related parameters differed markedly between the two conspecific populations. It is concluded that the only age- or length-related parameter associated with body growth or ossification of the skeleton that is liable to be affected by density-dependent forces is the body growth rate or, as a consequence, the age at attainment of sexual maturity.
Anatomical specialization in the gut of Pacific salmon (Oncorhynchus): evidence for oceanic limits to salmon production?
Authors: Welch D. W.
Published: April 2008

The stomach (but not the intestine) of chum salmon (Oncorhynchus keta) is greatly enlarged relative to that of other species of Pacific salmon. This permits the exploitation of gelatinous zooplankton (jellyfish, ctenophores, and salps), an abundant but low-energy prey unused by other species of salmon, as a major food source. The unique gut structure of chum salmon therefore allows efficient feeding on a little-exploited branch of the food web and reduces interspecific trophic competition. The development of this remarkable anatomical specialization suggests that salmon abundances were previously high enough that the resulting trophic competition led to evolutionary selection to reduce trophic competition. As total salmon abundances in the North Pacific are now probably the highest of this century, the carrying capacity of the ocean rather than that of fresh water could limit overall salmon production if abundances are once again approaching pre-exploitation levels.
Notes on age at dispersal of beaver (Castor fiber) in an expanding population
Authors: Hartman Göran
Published: April 2008

Movements of nine young beavers (Castor fiber) that were trapped at the front of an expanding population were monitored using radiotelemetry. Two years is generally considered the normal age at dispersal in beavers, but in this study the ages at dispersal were evenly distributed between 11 and 23 months. At least one of the females in the study gave birth at 2 years of age. Exploratory movements of three individuals outside the natal terrritory before the time of dispersal were observed. The observed plasticity in age at dispersal and parturition indicates that the rate of increase may be greater than expected at the front of expanding beaver populations.
The importance of beaver lodges in structuring littoral communities in boreal headwater lakes
Authors: France R. L.
Published: April 2008

The littoral zones of many boreal headwater lakes in northwestern Ontario are composed of rocks, boulders, and sand, with sparse macrophyte growth. This study investigated the possibility that abandoned beaver lodges might structure littoral communities in these systems through providing accumulations of coarse woody debris and entrapped sediment. The richness and abundance of 10 benthic macroinvertebrate taxa, 6 species of small fishes, and 2 species of amphibians were found to be significantly elevated near beaver lodges compared with areas of sand and rocks otherwise characteristic of the littoral zones in these lakes. Beaver in Ontario are generally regarded as a nuisance or a resource; wildlife managers therefore encourage extensive trapping before large populations can become established. The results of this study suggest that beaver provide an important habitat resource for littoral communities in boreal headwater lakes. As a result, endorsement of limiting beaver populations through increased trapping should be reexamined for regions containing macrophyte-impoverished lakes with a rocky shore.
Venom gland morphology in Pepsis pallidolimbata pallidolimbata and biological use and activity of Pepsis venom
Authors: Schoeters E. , Billen J. , Schmidt J. O.
Published: April 2008

Spider wasps, i.e., the family Pompilidae, in general, and those belonging to the genus Pepsis in particular, are acknowledged to possess venoms that are algogenic to humans and thus have the parsimonious functions of causing paralysis and providing defense against predators. The morphological organization of the venom system and its complex convoluted gland closely resembles that in social members of the Vespidae. These features distinguish the venom glands of the Pompilidae from those of the sibling family Mutillidae as well as those of the family Sphecidae, which lack convoluted glands. Although the venom glands in Pepsis species are very similar in morphology to those of social vespids, the lethality of Pepsis venom to mammals is several times less than that of the social common wasps. These findings suggest that in terms of the evolution of venom activity and the associated glandular structures, there was apparently no need for social wasps to develop extra parts of the venom system for producing toxic, lethal, or powerful algogenic components. All of the glandular parts of the venom gland of social wasps were already present in pompilids (and eumenids) and, presumably, in their ancestors.
Behavioural rhythmicity in transgenic growth hormone mice: trade-offs, energetics, and sleep–wake cycles
Authors: Rollo C. D. , Foss J. , Lachmansingh E. , Singh R.
Published: April 2008

Transgenic mice with extra rat growth hormone (GH) genes (TRrGH mice) are behaviourally lethargic and sleep 3.4 h/d longer than normal on standard diets. We tested the hypothesis that the doubling of the growth rate of TRrGH mice reduced the energy available for behaviour. Provision of sucrose supplements ad libitum normalized the durations of activity and sleep. Our results support a new allocative theory suggesting that sleep serves as an umbrella function for a suite of synergistic anabolic functions (e.g., growth, immunity, repair). Relegating these to the period of sleep in a secure nest allows full dedication of waking resources to niche interfacing (resource acquisition, risk avoidance and environmental stress resistance). Energy stress in TRrGH mice may arise via specific diversion of energy from waking functions via GH-induced insulin resistance. GH is normally secreted during sleep, but any causal relationship remains unresolved. We examined the circadian and ultradian behaviour of TRrGH mice to determine how a chronically elevated GH level impacts sleep. Remarkably, even the major hormonal distortion in TRrGH mice had little impact on the timing of ultradian or circadian rhythms. Increased sleeping of TRrGH mice on normal diets was due to an increased likelihood and duration of sleep at permitted times. GH did, however, appear to increase the depth of sleep.
Nest success and productivity of Ferruginous Hawks in northern Montana
Authors: Zelenak James R. , Rotella Jay J.
Published: April 2008

In 1993–1994, we investigated nest success and productivity of Ferruginous Hawks (Buteo regalis) in north-central Montana. The 171-km2study area contained a variety of habitats, a high density of breeding raptors, and 24 occupied Ferruginous Hawk territories. Only 42% of occupied nests produced fledglings. Occupied territories produced an average of 0.96 fledglings (SE = 0.19). Successful nests produced an average of 2.30 fledglings (SE = 0.21, n = 20). Lagomorphs were scarce on the area. Richardson's ground squirrels (Spermophilus richardsonii) were more numerous along the edges of cropfields and roads than in grasslands. Multiple regression indicated that Ferruginous Hawk nests closer to cropfields and roads and farther from other breeding raptors produced more young than other nests. Thus, habitats altered by humans, which were not extensive (20% cultivated), apparently had higher densities of ground squirrels and thereby benefited breeding hawks. However, because our multivariate analysis was exploratory and based on a moderate sample size, our results should be interpreted cautiously and further evaluated in future studies.
The relationship between testicular activity, accessory sex glands, and circulating steroid concentration during the reproductive cycle in a male Indian vespertilionid bat,Scotophilus heathi
Authors: Krishna A. , Singh Kavita
Published: April 2008

The relationship between spermatogenesis, accessory sex glands, Leydig cell activity, and circulating concentrations of testosterone and androstenedione in male Scotophilus heathi, the greater yellow bat, was studied. Scotophilus heathi accumulated fat prior to winter dormancy at Varanasi, India. Spermatogenesis was seasonal and extended over the period November to March, with the testes becoming quiescent during winter. Monthly changes in testis and accessory sex gland masses showed two peaks, in November and January. Accessory gland secretory activity and fructose concentration showed only one peak, during January and February, which coincided with the mating period. The mass in the epididymides and their histological changes reflect the influence of testicular spermatogenesis. However, sperm were found in the cauda epididymidis during the spermatogenically quiescent period of winter dormancy. The Leydig cells showed intense side chain cleavage (SCC) enzyme activity from August to December. In late January and February, males had smaller Leydig cells and low SCC activity. Monthly changes in serum testosterone concentration included two peaks in November and January, coinciding with peak spermatogenic activity, whereas androstenedione showed only one peak, an unusually high concentration in November. The circulating serum androstenedione concentration may be responsible for the unique reproductive activity noted in this bat.
Are staged dyadic encounters useful for studying aggressive behaviour of arvicoline rodents?
Authors: Harper Steven J. , Batzli George O.
Published: April 2008

We investigated the aggressiveness of adult prairie voles (Microtus ochrogaster) in dyadic encounters staged in different types of arena trials to determine if responses differed (i) between neutral arena trials conducted in the laboratory and resident–intruder trials conducted in the field, (ii) between trials staged before and after 3 months of isolation from social contact, (iii) between voles reared in the laboratory and voles reared in the field, and (iv) among trials staged with the same individual over time. Though rodents are usually expected to be more aggressive on their own home range, female prairie voles tended to be more aggressive in neutral arenas. Males showed no difference in aggression between trials held in neutral arenas and trials held in arenas placed in their home ranges. Aggressiveness was not affected by 3 months of isolation for either males or females, suggesting that recent social cues may not strongly influence aggressive behaviour in this species. Voles reared in the laboratory were significantly more aggressive than those reared in enclosed field populations, which suggests that direct comparisons of field and laboratory studies of aggressive behaviour may be suspect. Individuals showed little change in aggressiveness when tested over several weeks in three trials with different opponents. We conclude that encounters staged in arenas provide standardized estimates of aggressiveness that are robust to differences in testing procedures and are repeatable over time. Therefore, their continued use seems warranted for studying aggressive behaviour of voles and lemmings.
Liver energy metabolism during hibernation in the golden-mantled ground squirrel,Spermophilus lateralis
Authors: Staples James F. , Hochachka Peter W.
Published: April 2008

Large changes in ATP production capacities and rates have been reported in mammalian hibernators throughout the different stages of the hibernation cycle. In this study we showed that total extractable liver [ATP], [ADP], and [ATP]/[ADP] do not differ among summer normothermic, hibernating, and aroused golden-mantled ground squirrels, Spermophilus lateralis, indicating that metabolism remains well balanced throughout the hibernation cycle. This implies that rates of ATP consumption must be down-regulated during deep hibernation in order to maintain this balance. Despite this, basal oxygen-consumption rates [Formula: see text] of hepatocytes isolated from hibernating, aroused, and summer cold-acclimated ground squirrels were 22.4–35.1% higher than those from ground squirrels in the summer normothermic condition when measured at 37 °C. The relatively high hepatocyte [Formula: see text] may help to minimize interbout arousal times, reducing energy demands during the hibernation season. At 7 °C, hepatocyte [Formula: see text] values do not differ among the four groups; however, the Q10for hepatocyte [Formula: see text] is significantly lower for the summer group, suggesting lower temperature sensitivity. Despite the seasonal changes in thyroid hormone status known to occur in scuirid hibernators, the proportion of hepatocyte [Formula: see text] attributed to Na+,K+-ATPase, estimated by inhibition with 1 mM ouabain, is only around 15% and does not differ among hibernation/seasonal conditions.
Comparison of genetic variability of North and South Atlantic right whales (Eubalaena), using DNA fingerprinting
Authors: Schaeff Catherine M. , Kraus Scott D. , Brown Moira W. , Perkins Judy S. , Payne Roger , White Bradley N.
Published: April 2008

The North Atlantic right whale (Eubalaena glacialis) is the most endangered large whale in the world and shows few signs of recovery despite over 60 years of protection. In contrast, the South Atlantic right whale (E. australis), a closely related species, appears to be recovering successfully. Using DNA extracted from skin biopsy samples and two hypervariable minisatellite probes, we compared the levels of genetic diversity within the two populations. Our results revealed that unrelated North Atlantic (NA) right whales exhibit significantly less genetic variation than unrelated South Atlantic (SA) right whales (Jeffreys 33.15 (J33.15) probe: SNA-U-observed = 0.56 versus SSA-U-observed = 0.37, p < 0.01; M13 probe: SNA-U-observed = 0.74 versus SSA-U-observed = 0.46, p < 0.01). The level of band sharing among unrelated North Atlantic right whales was greater than that predicted for second-degree-related South Atlantic right whales (J33.15: SNA-U-observed = 56 versus SSA-2°-expected = 0.53, p < 0.05; M13: SNA-U-observed = 0.74 versus SSA-2°-expected = 0.60, p < 0.01), indicating that the northern animals have lost a substantial amount of genetic variability. Observed band sharing among North Atlantic first-degree relatives was lower than expected, based on band sharing among unrelated animals (J33.15: SNA-1°-observed = 0.67 versus SNA-1°-expected = 0.78, p < 0.01; M13: SNA-1°-observed = 0.83 versus SNA-1°-expected = 0.87, p = 0.15). This suggests that the matings between closely related individuals that would have resulted in the higher band-sharing values were unsuccessful. These results, in conjunction with behavioral and population data which indicate that North Atlantic right whales may be suffering from reduced fertility, fecundity, and juvenile survivorship, support the hypothesis that inbreeding depression is influencing the recovery of this species.
Post-emergent field activity and growth rates of hatchling spur-thighed tortoises,Testudo graeca
Authors: Keller Claudia , Díaz-Paniagua Carmen , Andreu Ana C.
Published: April 2008

Activity, mobility, growth rates, and space use of 48 hatchling spur-thighed tortoises, Testudo graeca, were monitored over a period of 8 months, from emergence from the nest in September until May. Individuals were followed by means of thread trailing and radio tracking. Overall average distance moved was 4.42 m/day and average home-range size was 13.7 m2. Hatchlings were active from emergence until mid-December, exhibited discontinuous hibernation until mid-February, and reached highest activity and mobility values in April–May. Overall, mobility varied significantly with daily solar radiation values and maximum temperature, and was significantly dependent on body condition in winter. Body size and mass had no influence on individual performance, and a significant proportion of variance among individuals remained unexplained. Little growth occurred in autumn and body condition decreased steadily, increasing only from February onwards. Growth rates increased in March–April. No individual differences in growth rates were detected, initial body size being the main determinant of body size after 8 months.
Responses of a predator to variation in prey abundance: survival and emigration of adders in relation to vole density
Authors: Forsman Anders , Lindell Lars Erik
Published: April 2008

We tested for effects of temporal and spatial variation in prey density on survival, growth, body condition, and emigration of a snake species feeding on voles. We carried out a capture–mark–recapture study (1989–1994) of two subdivided populations of adders, Vipera berus, inhabiting two groups of islands (Ängskär and In-Fredeln) in the Baltic Sea to estimate, compare, and model survival and capture probabilities, and to test for effects of time, locality, sex, and vole density on survival, using the computer program SURGE. To quantify variation in prey availability among years and localities we trapped field voles, Microtus agrestis, the primary prey of adders, every year from 1989 to 1993 on the islands where we captured snakes. We found that vole densities showed large fluctuations among years at In-Fredeln but remained relatively low throughout the study period at Ängskär. Annual survival probabilities of adders varied in a nonparallel manner through time between localities and ranged from 0.36 to 1.00, with a mean of 0.72 across years and localities. Survival did not differ between males and females. Survival of adders increased with population density of voles in one of the two populations (In-Fredeln), suggesting that starvation may have been an important source of snake mortality in some years, or that physiological stress resulting from food shortage may render individuals more susceptible to predators and diseases. Adders at In-Fredeln also grew faster and were in better body condition when vole density was high than when it was low. Inter-island movement rates of adders ranged from 0 to 29% among years but were not correlated with vole density, suggesting that the relationship between snake survival and vole density did not simply reflect increased emigration in years when prey were scarce.
Forage intake by black-tailed deer in a natural environment: bout dynamics
Authors: Gillingham Michael P. , Parker Katherine L. , Hanley Thomas A.
Published: April 2008

We examined the within-bout and seasonal dynamics of intake rate for free-ranging tractable black-tailed deer (Odocoileus hemionus sitkensis) throughout a 2-year period. Based on log frequency analyses of 487 complete active bouts, we concluded that active bouts consisted of a series of foraging bouts separated by ~2 min of nonforaging activity. Black-tailed deer spent ~92% of their active time foraging, independent of sex or season. Dry matter intake rates varied significantly with season, from ~0.5 g/min active in winter up to 1.5 g/min in summer, but few differences were attributable to sex. The large leaf size of skunk-cabbage (Lysichiton americanum) enabled deer to attain and sustain intake rates that approached predicted theoretical Rmaxvalues of 10–12 g dry matter/min (L.A. Shipley and D.E. Spalinger. 1992. Can. J. Zool. 70: 1743–1752). Daily dry matter intake varied from 300 g/day in winter to > 1300 g/day in summer. Deer maintained a constant intake rate throughout only one-third of all active periods; intake was reduced at the end of ~40% of-all bouts, while intake rates increased towards the end of 30% of bouts. We discuss the implications of these dynamics for sampling of incomplete bouts, which is frequently employed by observers. Finally, we discuss the importance of selected, not available, biomass in understanding the foraging intake of ungulates.
The formation, transfer, and fate of spermatophores in Photinus fireflies (Coleoptera: Lampyridae)
Authors: Reijden E. D. van der , Monchamp Jeff D. , Lewis Sara M.
Published: April 2008

Fireflies in the genus Photinus have been assumed previously to be among the many insect species in which males transfer primarily sperm during mating. In this study, male P. ignitus and P. marginellus were found to produce a complex proteinaceous spermatophore in four paired male accessory glands, a major component of the spermatophore being formed within prominent spiral glands. The spermatophore is transferred to the female within the first 40 min of copulation, and sperm bundles are released into the spermatheca. The remainder of the spermatophore subsequently undergoes digestion within a specialized sac in the female reproductive tract. To examine the function of male spermatophores, male P. marginellus were fed rhodamine B, resulting in the production of intensely fluorescent spermatophores. After mating with rhodamine-dyed males, females incorporated material derived from male spermatophores into their oocytes within 58 h post mating. Nutrient donations from males during mating are expected to play particularly important roles in female oogenesis in insects with nonfeeding adults, such as Photinus spp. The presence of spermatophores in Photinus is related to marked differences among species in their life histories, mating systems, and mating behaviors.
Evidence for proctolin-like and RFamide-like neuropeptides associated with the hindgut of the crayfish Procambarus clarkii
Authors: Mercier A. Joffre , Lange Angela B. , TeBrugge Victoria , Orchard Ian
Published: April 2008

Immunohistochemical staining revealed proctolin-like immunoreactivity in nerve endings associated with the hindgut of the crayfish Procambarus clarkii. Proctolin-like bioactivity, detected using both locust oviducts and crayfish hindguts for bioassays, co-eluted with authentic proctolin through five consecutive reversed-phase high-performance liquid chromatography (RP-HPLC) systems. This strongly suggests that proctolin (or a peptide very similar to it) is contained in nerve endings on the crayfish hindgut. RFamide-like immunoreactivity (RFLI) was extracted from the hindguts and intestinal nerves of crayfish and separated using RP-HPLC. Initial separation on a C18 column gave a broad peak of RFLI, and these fractions were bioactive on the crayfish hindgut. Subsequently, RFLI was separated on two additional RP-HPLC systems. The predominant peak could be distinguished from FMRFamide and several known FMRFamide-like peptides on the basis of elution times. Partial sequence analysis indicated the presence of a decapeptide having some sequence homology with leucomyosuppressin and SchistoFLRFamide. These results support earlier evidence that extended RFamide peptides may function as neurotransmitters or neuromodulators on the crayfish hindgut, and suggest a similar role for proctolin or a closely related peptide.