bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors controlling debris avalanche initiation
Authors: Buchanan P. , Savigny K. W.
Published: May 2008

Heavy rainfall during a January 1983 storm triggered numerous debris avalanches and associated debris torrents in the Smith Creek basin, western Whatcom County, Washington, United States. Four classes of debris avalanches are recognized: wedges, drainage depressions, logging roads, and discontinuity surfaces. Nine different debris avalanche headscarps that are representative of these four classes are studied in detail. The geometric configuration of each headscarp, the properties of soils comprising the headscarps, and water tables based on numerical models of hillslope hydrology are used in limit equilibrium slope stability analyses to back-calculate root cohesion (Cr) values at failure. The calculated values are consistent with those reported by others. Four groups of Cr values are proposed and correlated with forest vegetation: group I, understory, Cr range from 1.6 to 2.1 kPa; group II, scrub forest, Cr range from 2.1 to 2.5 kPa; group III, mixed forest, Cr range from 2.5 to 3.0 kPa; and group IV, old growth forest, Cr greater than 3.0 kPa. Circular and noncircular failure surfaces are tested to determine the most likely failure configuration. Most computer-generated failure surfaces are consistent with those observed in situ. One debris avalanche is attributed to hydraulic erosion rather than Coulomb shear. Soil matrix suction contributes significantly to slope stability under drained, initial conditions. Loss of soil matrix suction during rainstorms and loss of root cohesion at failure cause a sharp reduction of soil shear strength. The stability of each headscarp is modeled during a moderately severe comparison storm in December 1979. Failure was probable at only two of the nine sites, and field evidence of prior failure is found at one of these. Sites with group I vegetation were also susceptible to failure during this storm. Pore-pressure increases triggered the debris avalanches; however, soil depth, soil density, the presence of smooth bedrock discontinuities, and root cohesion are shown to be important factors controlling initiation locations. The conclusions of this study are based on modeling results, which are only verified by post-failure observations at the avalanche headscarps. Direct field measurement of the hydrologic and shear strength parameters is required before the modeling results and conclusions drawn can be confirmed. Key words: slope stability, debris avalanche, hydrology, root cohesion, forested hillslope, factor of safety, Whatcom County, Washington.
Performance data for a sloped reinforced soil wall
Authors: Fannin R. J. , Hermann S.
Published: May 2008

A sloped reinforced soil wall, comprising two sections with a different arrangement and spacing of geogrid reinforcement, was built and monitored for loading conditions of self-weight, a cycle of surcharge load, and permanent surcharge loading of the wall crest. Instrumentation was used to measure force and strain in the reinforcement, soil strain and temperature, and earth pressure. Performance data are reported for a period of 20 months following completion of construction and describe the response to loading. Interpretation of the data addresses properties of the reinforcement and soil which are used in design and allows an evaluation of creep behaviour of the polymeric reinforcement. Key words: reinforced soil, field monitoring, creep.
Erosion tests on four intact Ontario clays
Authors: Kamphuis J. W. , Gaskin P. N. , Hoogendoorn E.
Published: May 2008

Erosion tests were carried out on four natural intact cohesive soils from Ontario using laboratory flume tests with both clear water and water with sand in suspension. It was found that erosion was initiated at discontinuities. The critical shear stresses were low and were not related to the geotechnical properties of the soils. Higher rates of erosion occurred with the sand suspension, and erosion appeared to be controlled by the movement of the sand particles. It is suggested that where the eroding water contains particles in suspension, such as in river beds and along shorelines of cohesive soil, erosion may be controlled by the size of the particles rather than the properties of the cohesive soil or the eroding water. Key words: erosion, cohesive soil, flume test.
Estimating coefficient of consolidation from piezocone tests
Authors: Robertson P. K. , Sully J. P. , Woeller D. J. , Lunne T. , Powell J. J. M. , Gillespie D. G.
Published: May 2008

Data have been reviewed from sites in Europe and North and South America as well as published data from South Africa. The review has concentrated on dissipation data from piezocone tests (CPTU) to compare predicted coefficient of consolidation and permeability values using published interpretation techniques with available reference values. The results of this review have shown that the theoretical solutions provide reasonable estimates of the in situ coefficient of consolidation. Results were evaluated for pore-pressure data from different locations on the piezocone, and the least scatter in results was obtained with the pore-pressure element location immediately above the cone tip. A new correlation has been proposed to estimate in situ horizontal coefficient of permeability (kh) from piezocone dissipation data. Key words : in situ, coefficient consolidation, cone penetration test, permeability.
Application of Bayesian Kriging to subsurface characterization
Authors: Nobre M. M. , Sykes J. F.
Published: May 2008

A large number of geologic environments are composed of different layers of contrasting grain sizes. An accurate description of the locations of these stratigraphic units is necessary for defining flow-field boundaries. In groundwater contamination problems, preferential pathways are controlled by the hydraulic properties of these units. This work presents and applies a Bayesian Kriging technique to a subsurface characterization problem. Expertise guesses with given uncertainties are included in the estimation procedure. This technique assures that observation data (hard data) prevail in areas close to observation points, whereas in areas without observations the guesses (soft data) have greater influence. Maps of the estimates and the associated uncertainties are shown to be key tools in reflecting the quantity and quality of the available data. The Simple and Universal Kriging become subsets of this procedure. Key words : Kriging, subsurface characterization, conditional simulation, geostatistics.
A novel technique of electrical strengthening of soft sensitive clays by dielectrophoresis
Authors: Lo K. Y. , Ho K. S. , Inculet I. I.
Published: May 2008

A novel technique of electrical strengthening of soil by dielectrophoresis was developed. The process employs an alternating current at high voltage, generating a converging electric field towards the electrode by which a net resultant movement of water in the clay mass is produced towards the direction of stronger electric field intensity. Laboratory tests were developed to investigate the mechanism of this process and to explore the possibility of its application in electrical strengthening of soft sensitive clays. The preliminary results of this study showed that the process is effective, and the shear strength of the treated clay (Wallaceburg clay) increased drastically by several times with a reduction of moisture content of approximately 25% at an applied electric potential of 20 kV for 28 days. When compared with electro-osmosis, similar results are obtained in dielectrophoresis, such as the increase in preconsolidation pressure, decrease in sensitivity, and improvement of stress–strain behaviour. It is also shown that the improvement of soil properties can be greatly enhanced by increasing the applied voltage and electrode depth. Key words : dielectrophoresis, alternating current, converging electric field, high-voltage electrode, dielectric constant, electro-osmosis, soft sensitive clay, shear strength, consolidation.
Design, construction, performance, and repair of the soil–bentonite liners of two lagoons
Authors: Chapuis Robert P. , Lavoie Jacques , Girard Doris
Published: May 2008

A sand–bentonite mix was used to form the liner of four lagoons for the La Tuque and Haute-Mauricie sewage water treatment project. This paper describes the site conditions, design, and construction of the lagoons. Since the results of the control tests on the sand–bentonite were satisfactory, it was expected that the liner would be as impervious as it was designed to be. Such control tests, however, provide local values that can give only an indirect prediction of the waterproofing of each lagoon. The global performance was evaluated in 1988, after filling the lagoons, by comparing their leakage rates with the design theoretical values. The performance of two of the lagoons was satisfactory, whereas the two other lagoons lost 10 times more water than the maximum leakage rate allowed in the specifications. An analysis of the various factors influencing the global performance is developed to explain these contradictory performances, which cannot be explained by the usual deterministic method used in design. The paper demonstrates how to analyze the graph of the total leakage rate of a lagoon to determine where the main hydraulic defects are located and whether or not they are deteriorating. Several techniques for repairing the lagoons were considered and are described. The technique selected was the underwater injection of a bentonite slurry of adequate viscosity. Repairs were successfully completed during the summer of 1989. Key words : impervious liner, soil, bentonite, permeability, case history.
Rock mass movements across bedding in Kananaskis Country, Alberta
Authors: Hu Xian-qin , Cruden D. M.
Published: May 2008

Rock mass movements in sedimentary rocks across bedding in Kananaskis Country, Alberta, are controlled by discontinuity orientations and topography. When bedding planes dip at less than 50°, small rock masses can slide along strike joints or fall and slope angles remain unchanged. When bedding surfaces dip at 65–70°, large rock masses topple and then slide or simply slide along sheeting joints or combinations of bedding surfaces and strike joints to reduce slope gradients. Block toppling and sliding models of large slope movements in highly jointed rock masses indicate that toppling mode is more critical than the sliding mode. A natural example, the 6 × 106 m3 Elk Ridge landslide, shows toppling from bedding planes followed by sliding can be catastrophic. Key words : topple, slide, landslide, rock, Rockies.
Similarity of internal stability criteria for granular soils
Authors: Chapuis Robert P.
Published: May 2008

Internal instability produces segregation in fine particles, modifies drainage properties, and increases pore pressures, capillary retention, and possible frost damage. Three criteria are commonly used to assess the internal instability of granular soils. It is shown here that they can take similar mathematical expressions where the secant slope of the grain-size distribution curve indicates the risk of internal instability. Key words : suffossion, groundwater flow, gradation.
A new computerized approach to estimating the thermal properties of unfrozen soils
Authors: Tarnawski Vlodek R. , Wagner Bernhard
Published: May 2008

Results from a user friendly, menu-driven, and interactive computer program for rapid estimation of thermal properties of soils are presented. The model developed is an extension of the de Vries approach. The new model allows easy estimation of the thermal conductivity of soils with approximately log-normal particle-size distribution. The model introduces the individual characteristics of five main mineral soil constituents (i.e., quartz, feldspar, calcite, clay minerals, and mica) and relates their occurrence in individual soils to grain-size distribution. The user also has a possibility of inserting to the model up to 20 additional mineralogical components, providing that mass fraction, thermal conductivity, density, shape, and specific heat are known. Soil-water hydraulic relations follow an extended power function model and allow the calculation of the apparent thermal conductivity of soils (water-vapor migration) at low moisture contents. Thus the model predicts soil thermal conductivity in a full range of moisture content from dryness to saturation and a temperature range of 0–95 °C. Good agreement with experimental data was reported. Key words : moist soils, soil thermal properties, thermal conductivity, specific heat, de Vries method.
A review of the influence of clay–brine interactions on the geotechnical properties of Ca-montmorillonitic clayey soils from western Canada
Authors: Barbour S.L. , Yang N.
Published: May 2008

Natural Ca-montmorillonite clay soils or engineered clay barriers in western Canada are often used to contain brine generated from the surface disposal of potash tailings or from drilling activities associated with the oil and gas industry. The performance of these barriers has ranged from excellent to poor. The influence of salt brines on the geotechnical properties of these soils has been recognized as a potentially important factor for some time. It has been well documented in the literature that the behavior of clayey soils is strongly influenced by physicochemical interactions between clay particles and pore-fluid chemistry; consequently, the properties of these soils are sensitive to changes in the electrolyte concentration of the pore fluid. An increase in the concentration of the pore fluid to the levels of a concentrated brine can cause significant changes in the geotechnical properties of the soil. In this paper, the impact of brine contamination on the geotechnical properties of two Ca-montmorillonitic clayey soils of glacial origin from western Canada is reviewed. The influence of clay–brine interactions on the index properties (liquid limit, plastic limit, plastic index, mineralogy, density, grain size, and compaction characteristics), mechanical properties (volume change and shear strength), and hydraulic properties (hydraulic conductivity) is described. A quantitative explanation for the changes that occur in the hydraulic and mechanical properties of these soils as a result of brine permeation is also provided. This explanation relates the changes in pore-fluid chemistry to changes in an effective physicochemical stress state. This approach may be used to predict the changes in hydraulic conductivity, volume, or shear strength of a clayey soil as a result of brine contamination. Key words : clay–brine interactions, diffuse double layer, hydraulic conductivity, soil structure, physicochemical.
Evaluation of the saturated–unsaturated groundwater conditions of a thickened tailings deposit
Authors: Barbour S. Lee , Wilson G. Ward , St-Arnaud L.C.
Published: May 2008

The method of thickened tailings disposal has been in use at an active copper–zinc mine near Timmins, Ontario, for approximately 25 years. The thickened tailings deposit that has been formed was investigated. Field and laboratory tests were conducted to determine particle-size distribution at various horizontal locations, in situ values of hydraulic conductivity, moisture-retention characteristics, groundwater levels, and in situ water contents. The results of the investigation show that the thickened tailings deposit is relatively homogeneous. Shallow groundwater levels were also observed to follow the gently sloping topography of the tailings surface. Upward-seepage analyses were conducted for various steady-state evaporative fluxes. The analyses showed the tailings tend to maintain saturated conditions for the highest potential rate of evaporation observed. The ability of the tailings to maintain saturation is attributed to the shallow groundwater levels and the high air-entry value of the tailings. The tendency to saturated conditions at the tailings surface is a positive result. Saturated conditions in the tailings minimize the diffusion of atmospheric oxygen into the tailings. This aids in the prevention of acid generation in these tailings, which have the potential to oxidize and produce acid drainage. Key words : tailings, saturation, evaporation, acid generation.
Comparison of analytical snow pressure models
Authors: McClung D.M.
Published: May 2008

Two analytical models for snow creep and glide forces on structures in deep snow covers are compared theoretically and checked against field data. The results show that the formulations contained in the 1990 Swiss guidelines for avalanche defence are incompatible with a continuum mechanical model based on linear creep and glide constitutive equations. In addition, the formulations in the 1990 Swiss guidelines neglect the pressure from the component of body force in the slope-normal direction, which is an unnecessary simplification. Key words : snow pressure, quasi-static, creep, glide, deep snow cover, continuum.
Stress measurements in high-stress zones using the modified doorstopper technique
Authors: Corthésy Robert , Gill Denis E. , Leite Maria Helena , Thompson Paul M.
Published: May 2008

Of the existing in situ stress-measurement techniques, the doorstopper is particularly suited for use in highly stressed zones where core discing may occur. The main reason is that the doorstopper requires a very short intact core length to obtain a valid measurement in comparison with other techniques that use overcoring to perform stress relief, such as borehole-deformation gauges, CSIR (Council for Scientific and Industrial Research), and CSIRO (Commonwealth Scientific and Industrial Research Organization) gauges. The paper presents stress-measurement results obtained with the modified doorstopper technique in highly stressed granite, at the Underground Research Laboratory (URL) of Atomic Energy of Canada Limited. A brief description of the modified doorstopper technique and of a stress-calculation model that includes the nonlinear anisotropic behaviour found in highly stressed rocks is made. Stress-measurement results obtained at the URL with different techniques are compared with those obtained with the modified doorstopper cell. Key words : doorstopper, high stresses, anisotropy, nonlinear elasticity, core discing.
Effect of overburden pressure on liquefaction resistance of sand
Authors: Pillai V.S. , Byrne P.M.
Published: May 2008

The effect of overburden pressure on liquefaction resistance of sand is studied and results of a site-specific investigation are presented. When estimating liquefaction resistance of sand from the indirect approach using the chart suggested by Seed et al. (1984) a correction factor Kσ is applied to account for vertical effective overburden stresses larger than 1 tsf. Published data indicate a decrease in Kσ with increased confining stress but with a wide range of Kσ values for the same confining stresses, predicting significantly differing liquefaction resistance. The effect of confining stresses on liquefaction resistance was investigated as part of a comprehensive seismic assessment of Duncan Dam in British Columbia. The results indicate that Kσ is dependent on confining stresses and the relative density of the soil, and values are generally significantly higher than much of the previously published data. Key words : liquefaction, sand, confining stress, density, cyclic resistance ratio.
Pullout behaviour of model pile and helical pile anchors Subjected to lateral cyclic loading
Authors: Prasad Y.V.S.N. , Rao S. Narasimha
Published: May 2008

This paper presents the effect of lateral cyclic loading on the pullout capacity of model and helical piles in clayey soil. The tests were conducted on short rigid model piles in the laboratory in three phases, namely lateral static load tests, lateral cyclic load tests, and vertical pullout tests. From the test results it was found that the lateral cyclic loading affects the pullout capacity of piles substantially. Reduction in pullout capacity mainly depends upon the lateral deflection of the pile during cyclic loading and the embedment ratio of the pile. This reduction in the pullout capacity of model piles is presented in terms of nondimensional parameters, viz., degradation factor, lateral deflection ratio, and embedment ratio of pile. However, in the case of helical piles under similar conditions, it was found that the lateral cyclic loading has very little influence on the pullout capacity. The reasons for the better performance of helical piles over ordinary piles are explained. Key words : clay, degradation factor, helical pile, lateral cyclic loading, lateral deflection, Joading level, pile, pullout capacity.
Fungal and bacterial communities across meadow–forest ecotones in the western Cascades of Oregon
Authors: Kageyama Stacie A. , Posavatz Nancy Ritchie , Waterstripe Kirk E. , Jones Sarah J. , Bottomley Peter J. , Cromack Kermit , Myrold David D.
Published: May 2008

Meadows are natural dynamic features of forested mountain landscapes of the Pacific Northwest. Proportions of meadows and forests change with environmental conditions and disturbance history. We investigated the belowground microbial communities associated with these two vegetation types and how they change across the meadow–forest transition at two sites in Oregon. Soils were sampled along replicate transects extending from meadow into forest. We quantified total bacterial and fungal biomass using direct microscopy and described the composition of bacterial and fungal communities using a DNA-based fingerprinting technique. Bacterial biomass was similar in meadow and forest soils, but fungal biomass was significantly higher in forest soil. Meadow and forest soils had distinct communities of bacteria and fungi. Bacterial communities near the meadow–forest boundary reflected current vegetation, but fungal communities under meadow vegetation near the forest edge were intermediate in composition between those found in meadow and forest soils. The more gradual transition observed with fungal communities may reflect the influence of tree roots and their associated ectomycorrhizal fungi or possibly colonization by saprotrophic fungi associated with tree litter accumulating near the forest edge. Invasion of forest-associated fungi into the meadow soils may presage subsequent expansion of forest vegetation into meadows.
An assessment of the reproductive biology of Yellowstone bison (Bison bison) subpopulations using noncapture methods
Authors: Kirkpatrick J. F. , McCarthy J. C. , Gudermuth D. F. , Shideler S. E. , Lasley B. L.
Published: May 2008

Five parameters of reproductive biology (number of live calves, rates of tending lactating and nonlactating cows, and age-specific calving and pregnancy rates) were measured for the Mary Mountain (≈2500) and Northern Range (≈600) herds of bison (Bison bison) in Yellowstone National Park between 1990 and 1993. Three physiological events (ovulation, pregnancy, fetal loss) affecting reproductive success were measured using urinary or fecal steroid analysis. Adult Mary Mountain cows had significantly fewer pregnancies and calves than the Northern Range cows. Approximately 85% of cows tended by bulls, 76% of detected ovulations, and 78% of detected fall pregnancies were among nonlactating cows. Greater than 80% of all pregnancies occurred in cows ≥4 years old in both herds. However, 100% of all pregnancies among lactating cows occurred in cows ≥5 years old in both herds. In the Mary Mountain subpopulation, only 5% of all pregnancies were among cows <4 years old, while 14.2% of all pregnancies in the Northern Range herd occurred in cows in the same age group. These data indicate that (i) the number of live calves and the pregnancy rate are significantly reduced among lactating cows, (ii) reproductive failure among lactating cows is primarily caused by ovulation failure, (iii) lactating cows that successfully reproduce are exclusively animals ≥5 years old, and (iv) the results of urinary or fecal steroid analysis are consistent with behavioral and demographic data and can be used to evaluate specific aspects of reproductive physiology among free-ranging ungulates.
Psolidium bidiscum, a new shallow-water psolid sea cucumber (Echinodermata: Holothuroidea) from the northeastern Pacific, previously misidentified as Psolidium bullatum Ohshima
Authors: Lambert Philip
Published: May 2008

A common west-coast psolid sea cucumber, formerly identified as Psolidium bullatum Ohshima, 1915, is described as a new species. Psolidium bidiscum n.sp. has two types of ventral ossicles, one type of dorsal cup, and 10 scales between the mouth and anus. Psolidium bullatum Ohshima, 1915 has one type of ventral ossicle, no dorsal cups, and 19 scales between the mouth and anus. Psolidium bidiscum is known from southeastern Alaska south to Monterey, California, between 0 and 200 m in depth. Psolidium bidiscum is compared with six other species of Psolidium from the eastern Pacific.
Feeding, distribution, and reproductive behavior of cyamids (Crustacea: Amphipoda) living on humpback and right whales
Authors: Rowntree Victoria J.
Published: May 2008

Cyamids are little-known amphipod crustaceans that live only on cetaceans. Specimens were collected from strandings of three right whales (Eubalaena glacialis) and one humpback whale (Megaptera novaeangliae). The intestinal contents of cyamids from the humpback whale indicated that they feed on a layer of whale skin containing pigment. The single species of cyamid from the humpback whale had a male-biased sex ratio (70% male) and its distribution indicated that males were competing for access to females. Two species of cyamids from the callosities of right whales occurred in different microhabitats. No reproductive synchrony was found between cyamids and their hosts. A species of cyamid that occurs in large patches on the head of young right whale calves disappears from the head when calf growth slows at approximately 2 months of age; this habitat shift may indicate a change in the quality or quantity of new skin.
Pararetinometra lateralacantha Stock and Holmes, 1981 (Cestoda: Hymenolepididae): the first record in the Palaearctic region and comments on its morphology and taxonomy
Authors: Vasileva Gergana P. , Georgiev Boyko B. , Genov Todor
Published: May 2008

Pararetinometra lateralacantha Stock and Holmes, 1981, known until now only from Alberta, Canada, as a parasite of three species of grebes (Aves: Podicipediformes: Podicipedidae), was found in a wintering Podiceps nigricollis (Brehm) on the Bulgarian coast of the Black Sea. The species is redescribed and illustrated on the basis of both the Bulgarian specimens and specimens from Canada (paratypes). Some corrections or additions to the original description in relation to the characteristics of the rostellum, rostellar sheath, vitellarium, ovary, testes, cirrus sac, cirrus, and vagina are presented. In contrast to a recent opinion, Pararetinometra Stock and Holmes, 1981 is regarded as a valid genus and not as a synonym of Cladogynia Baer, 1937. The geographical distribution of P. lateralacantha is supposed to be circumboreal.
Body composition and nutrient reserves of arctic caribou
Authors: Gerhart K. L. , White R. G. , Cameron R. D. , Russell D. E.
Published: May 2008

We determined seasonal changes in body mass and composition of arctic caribou (Rangifer tarandus granti) in relation to age and reproductive status. Chemical composition was determined for 37 caribou calves from the Central Arctic Herd ranging from 1 to 134 days of age and for 15 adult females collected from the same herd in October, May, and July. Body composition of 5 fetuses from the Central Arctic Herd, 13 calves from the Porcupine Herd, and 10 captive male reindeer (R. t. tarandus) was determined for comparison. Between October 1989 and May 1990, body fat and protein of adult females declined by maxima of 45 and 29%, respectively; an additional 32% of fat was lost between May and July. Mobilization of large amounts of fat and protein suggests winter undernutrition. Chemical composition and growth patterns of calves did not differ between the herds. The growth rate of Central Arctic Herd calves was high during the first 28 d post partum (402 g/d), but both growth rate and fatness declined between 4 and 6 weeks of age (to 306 and −18.3 g/d, respectively), perhaps in response to insect harassment. Birth masses of males and females did not differ, but by autumn, male calves were 9.1 kg heavier than females. Chemical components (water, fat, protein, ash) were highly correlated with body mass, ingesta-free body mass, and carcass mass. Percentages of fat and water were inversely related, but the intercept decreased with age. Marked seasonal hypertrophy of liver and kidneys was noted in caribou, suggesting the presence of mobilizable protein reserves. Seasonal changes in organ masses may also reflect variations in metabolic activity and nutrient intake.
Geographic variation in the polytene chromosome banding pattern of the Holarctic midgeChironomus(Camptochironomus)tentans(Fabricius)
Authors: Kiknadze Iya I. , Aimanova Karlygash G. , Gunderina Larissa I. , Butler Malcolm G. , Cooper J. Kevin
Published: May 2008

Polytene chromosomes of Chironomus (Camptochironomus) tentans from Europe, Siberia, and North America were examined to clarify genetic relationships among widely distributed populations of this Holarctic midge. This first extensive cytogenetic analysis of Siberian populations confirms earlier suppositions that C. tentans karyotypes are quite uniform across the Palearctic from western Europe to Yakutia. Greater differences exist among North American populations in Minnesota, Michigan, and Massachusetts, and as a group, these Nearctic populations share so few banding sequences with Palearctic C. tentans that recognition of discrete sibling species on each contintent is warranted. Photomaps of polytene chromosomes for both Palearctic and Nearctic sibling species are presented, and banding sequences are described with standardized notation. In total, 42 inversion sequences were found in the 18 Siberian populations examined, 15 of which were previously undescribed. Of the 19 sequences found in the three American populations studied, only 6 were shared with the Palearctic. Three of the seven chromosome arms in Nearctic C. tentans had no sequences in common with European populations and four shared none with Siberian populations.
The relation between urinary cortisol levels and social behaviour in captive timber wolves
Authors: McLeod Peter J. , Moger William H. , Ryon Jenny , Gadbois Simon , Fentress J. C.
Published: May 2008

The relation between involvement in aggressive interactions and a physiological index of stress was examined in a captive timber wolf pack (Canis lupus). Urine samples from known individuals were collected from snow throughout the mating season and analyzed for levels of the stress responsive hormone cortisol. When expressed relative to creatinine concentrations in the sample (thereby correcting for differences in urine concentration and dilution in snow), individual differences in urinary cortisol levels were found. These differences were consistent with behavioural data on aggression collected during the same period. Although males engaged in intrasexual aggression more frequently, female aggression was more serious in that females were more likely to be the targets of group chases and attacks. The dominant and only breeding female also aggressed against the two highest ranking males during courtship and mating contexts. The lowest ranking female had a significantly higher cortisol:creatinine (C:C) ratio than all other females, and the second-ranking (beta) and most aggressive male, whose social position was unstable, had significantly higher C:C ratios than most other males. The data also suggest that urinary C:C ratios increase during the mating season for at least some individuals and vary in response to acute social stressors. The C:C ratios presented are similar to those reported from the urine of domestic dogs and a small sample of wild wolves, suggesting that these data from captive animals are not unusual. Comparisons with literature on primates and potential applications of these techniques are briefly discussed.
Catchability in snakes: consequences for estimates of breeding frequency
Authors: Bonnet Xavier , Naulleau Guy
Published: May 2008

Estimates of breeding frequencies in wild populations occupy a central place in life-history studies, but they remain hard to obtain in snakes. Capture–recapture procedures were carried out during 27 periods over 3 years in a large population of female asp vipers, Vipera aspis (317 marked individuals). Catchability was greater in reproductive females (2.64 ± 1.74 (SD) captures/year) than in nonreproductive females (1.76 ± 1.02). Three different methods were used to estimate breeding frequency: (i) the proportion of reproductive to nonreproductive females for each period (noncorrected estimates, NC) was measured; (ii) the ratio of the number of reproductive females to the total number of females was estimated using the CAPTURE program (catchability-corrected estimates, CE); (iii) breeding frequencies of marked individuals were observed in the field for 3 years (observed breeding frequency, OF). The results obtained with the three methods were different. The NC procedure indicated that 63% of females breed each year, suggesting an annual–biennial cycle. The CE (34% reproductive females) and OF (34% reproductive females) procedures both suggested a triennial cycle. The OF method was the most accurate; breeding frequencies were overestimated with the NC method. The NC method is the one most commonly used, and estimates of breeding frequency in snakes obtained in these studies may be imprecise. We conclude that differential catchability between reproductive and nonreproductive females should be taken into account in estimating breeding frequencies.
Annual variation in body composition of roe deer (Capreolus capreolus) in moderate environmental conditions
Authors: Hewison A. J. M. , Angibault J. M. , Bideau E. , Vincent J. P. , Boutin J. , Sempéré A.
Published: May 2008

Patterns of growth and seasonal variation in body mass, kidney fat level, and bone marrow fat level were investigated in a roe deer population south of Paris. Size dimorphism was not apparent until the deer were 2 years of age, following a second period of rapid growth in males during spring–summer. No differences between the sexes in fat accumulation or in the periodicity of the annual fat cycle were observed. However, annual cycles of adult body mass were asynchronous between the sexes. Carcase mass was stable for much of the year, but one marked seasonal decline was observed in animals of each sex. For females (April–August) this reflected investment in late gestation and lactation, but among males (April–November) it was presumably linked to the costs of rutting. Contrary to reports for other ungulates, no over-winter decline in adult carcase mass, kidney fat level, or bone marrow fat level was observed, possibly because winters were mild. All four fat indices (kidney fat index, three bone-marrow fat indices) declined over spring–summer. This seasonal cyclicity does not match the energy requirements of reproductive activity, suggesting that the fat cycle is intrinsic, linked to seasonal metabolic variation in roe deer. We suggest that carcase mass is a more reliable index of condition in roe deer.
Milk consumption and growth efficiency in Antarctic fur seal (Arctocephalus gazella) pups
Authors: Arnould J. P. Y. , Boyd I. L. , Socha D. G.
Published: May 2008

The body composition, milk consumption, and growth efficiency of Antarctic fur seal (Arctocephalus gazella) pups were measured over three consecutive lactation periods (1990–1992) at Bird Island, South Georgia. The body composition of pups differed between the sexes; whereas for any given age females were lighter than males, they had proportionately higher body lipid reserves than males. Milk consumption was determined on 388 occasions in 177 pups. Mean estimates of milk consumption ranged from 2.5 to 3.2 kg (42–53 MJ) during the 6-day perinatal period and from 2.9 to 3.6 kg (49–68 MJ) during the 1- to 2-day maternal attendance periods (feeding bouts). There were no differences in milk consumption between the sexes in any year. Both per-bout and per-day milk consumption increased steadily with age before decreasing significantly in the last 30–40 days of lactation. Per-bout milk consumption was positively related to the duration of the maternal foraging trip and attendance cycle, and both per-bout and per-day milk consumption were related to pup mass. Pups of both sexes consume the same amount of milk, but males direct more of their milk consumption into lean tissue growth than females, which accumulate greater adipose stores. Therefore, mass and mass changes may not be appropriate parameters for investigating differential maternal investment between the sexes in otariid pups.
Estimating past and present sex ratios of sea turtles in Suriname
Authors: Godfrey Matthew H. , Mrosovsky N. , Barreto R.
Published: May 2008

Leatherback (Dermochelys coriacea) and green (Chelonia mydas) sea turtles in Suriname lay eggs over several months of the year. During this nesting season, changes in rainfall produce changes in sand temperature, which in turn influence the sexual differentiation of incubating sea turtle embryos. The overall sex ratio of leatherback and green sea turtle hatchlings produced at Matapica beach in Suriname was investigated. Estimates of the sex ratios of these turtles in 1993 (green turtles 63.8% female, leatherbacks 69.4% female) were roughly 10% more female-biased than those from an earlier study in 1982. For both species, a significant negative relationship was found between monthly rainfall and monthly sex ratios. Using this relationship and data on rainfall in the past, it was possible to estimate overall sex ratios for an additional 12 years. These estimates varied considerably among different years, ranging from 20 to 90% female in the case of green turtles. Nevertheless, males tended to be produced primarily in April and May, while some females were produced in all months. Such seasonal patterns of production of turtles of different sexes have implications for sea turtle conservation programs that involve manipulating or harvesting eggs.
Effects of supplemental calcium on the reproductive output of a small passerine bird, the House Wren (Troglodytes aedon)
Authors: Johnson L. Scott , Barclay Robert M. R.
Published: May 2008

The normal food of most small birds (insects, seeds, and fruit) contains relatively little calcium. Birds must therefore supplement their diets, and those of their dependent young, with bits of calcium-rich material such as bone, limestone, eggshells, and mollusk shells. In this study, the question of whether the availability of calcium constrains reproductive output in a Wyoming population of the House Wren (Troglodytes aedon), a small insectivorous passerine, was asked. A randomly selected group of breeding pairs was provided with a mix of crushed oystershell and chicken eggshell at their nests for the duration of their breeding cycles. Calcium-supplemented birds tended to lay more eggs per clutch and tended to raise fledglings with slightly longer feathers than unsupplemented control birds. Calcium-supplemented birds did not, however, lay larger eggs, produce more fledglings, or produce fledglings of greater mass than control birds. Unlike the situation in many anthropogenically acidified environments, calcium availability apparently does not constrain the reproductive output of House Wrens breeding in this one environment that appears to be relatively unaffected by acidic precipitation.
Seasonal pattern of ovarian growth and interrelated changes in plasma steroid levels, vitellogenesis, and oviductal function in the adult female soft-shelled turtleLissemys punctata punctata
Authors: Sarkar Supriti , Maiti B. R. , Sarkar N. K.
Published: May 2008

The female reproductive cycle of the freshwater soft-shelled turtle Lissemys punctata punctata was studied by correlating ovarian growth with changes in plasma levels of steroids (17β-estradiol and progesterone), vitellogenic indices (calcium, lipid, protein, and cholesterol), and oviductal changes (growth, glycogen, and peroxidase levels). Ovarian growth starts after winter hibernation, proceeds slowly during the preparatory phase (March–June), becomes rapid in the recrudescent phase (July), and peaks in the breeding phase (August–September). Subsequently, the follicles undergo atresia in the regressive phase (October–November), which is followed by the quiescent phase (December–February) marked by negligible ovarian growth. Plasma levels of 17β-estradiol and vitellogenic indices reflect the same pattern of change as ovarian growth. The plasma progesterone concentration remains low throughout the reproductive cycle, except that the titre reaches a postovulatory peak and then declines prior to oviposition. Oviductal mass and glycogen and peroxidase concentrations correspond to changes in plasma estradiol concentration. The findings indicate that the seasonal reproductive cycle of L. p. punctata is characterized by a single annual peak of ovarian growth and estrogen secretion compared with a double peak recorded in other single-clutch turtles.
Bats in riverine forests and woodlands: a latitudinal transect in southern Africa
Authors: Rautenbach I. L. , Whiting M. J. , Fenton M. B.
Published: May 2008

Using captures in mist nets and monitoring echolocation calls, we quantified bat distribution and activity and measured insect abundance as numbers of insects attracted to black lights at 15-min intervals. These data were collected simultaneously at pairs of sites in riverine and dry woodland savannah along a transect of ca. 350 km from north to south in the Kruger National Park, South Africa. The sites were situated in the north, central, and south of the park and data were collected in January 1993. Our study involved 18 sites, three pairs each in the areas of the Luvuvhu, Letaba, and Sabie rivers. Half of the sites were in riverine woodland, the others in dry woodland. No statistical association exists between bat captures and either bat activity or insect abundance. Bat activity, however, was related significantly to insect abundance. Although bats were significantly more abundant (captures) in riverine habitats than in dry woodland savannah, comparisons of bat diversity and evenness (rarefaction curves, species abundance curves, and Whittaker plots) showed no differences between these habitats. The data neither demonstrate a decline in bat diversity away from the equator nor suggest specific bat communities associated with riverine habitats. The data do demonstrate the important influence of insects on the activity patterns of insectivorous bats.
Revised karyotypes and chromosome banding of coregonid fishes from the Laurentian Great Lakes
Authors: Phillips Ruth B. , Reed Kent M. , Ráb Petr
Published: May 2008

Karyotypes of lake whitefish, Coregonus clupeaformis, and various Great Lakes cisco species, lake herring or cisco, C. artedi, bloater, C. hoyi, blackfin cisco, C. nigripinnis, and shortjaw cisco, C. zenithicus, were analyzed using Giemsa staining, C-banding, silver staining, and Chromomycin A3 fluorescence. Coregonus clupeaformis had a karyotype (2n = 80, NF = 98) indistinguishable from that described for C. laveretus from Europe, with one pair of nuclear organizer regions (NORs) on the short arms of a small acrocentric chromosome pair and a second NOR on the short arms of another acrocentric chromosome pair. This species displayed a size polymorphism involving the heterochromatic short arm of the largest metacentric–submetacentric pair. All four cisco species had similar karyotypes (2n = 80, NF = 98), with the exception of some C. artedi from Lake Superior, which were heterozygous for a chromosome fusion involving the NOR chromosomes (2n = 79). One NOR was located pericentromerically on the long arm of the second largest acrocentric chromosome and a second NOR on the short arms of another acrocentric chromosome pair in several individuals. C-banding revealed that the difference in chromosome morphology between lake whitefish and the ciscoes probably resulted from amplification of heterochromatin on the short arms of one pair of large submetacentric–metacentric chromosomes.
Behaviour and dive times of Arnoux's beaked whales, Berardius arnuxii, at narrow leads in fast ice
Authors: Hobson R. P. , Martin A. R.
Published: May 2008

Groups of the little-known Arnoux's beaked whale, Berardius arnuxii, were observed at narrow cracks or leads in sea ice near the Antarctic peninsula during the austral summer of 1992–1993. The whales were grey, had a slightly asymmetric blowhole and blow, and were heavily scarred in adulthood. At least 30 animals were uniquely identified using their scars. Despite often cramped conditions at the breathing holes, the whales were always calm and nonaggressive, reacting to the circumstances with surfacing and submerging behaviour involving little horizontal movement. Seventy dive durations by 17 identified adults were recorded, with a mode of 35–65 min and a maximum of at least 70 min. Eight periods of respiration varied between 1.2 and 6.8 min, with an average of 9.6 blows/min. These breath-hold characteristics confirm B. arnuxii as one of the most accomplished mammalian divers, capable of swimming up to an estimated 7 km between breathing sites in sea ice. Whales moved to and from the observed lead, apparently able to find other breathing sites in what appeared to be unbroken ice. The species seems well adapted to life in ice-covered waters and may be able to exploit food resources inaccessible to other predators in the region.
Temporal patterns of parasitoid fly (Ormia ochracea) attraction to field cricket song (Gryllus integer)
Authors: Cade William H. , Ciceran Mark , Murray Anne-Marie
Published: May 2008

Female flies, Ormia ochracea (Diptera, Tachinidae), orient to the calling song of the field cricket Gryllus integer (Orthoptera, Gryllidae) and deposit larvae that burrow into and consume the cricket host. Selection pressure from O. ochracea has probably been important in the evolution of male cricket songs and mating behaviour in G. integer and other cricket species. Tape-recorded G. integer calling song was broadcast to study the temporal rate of attraction of O. ochracea. Flies became phonotactic to cricket song approximately at sunset, and the highest level of attraction was observed in the following hours of the evening. Fly phonotaxis decreased in the hours immediately preceding sunrise and no flies were attracted during daylight hours. More male G. integer call at sunrise and in the preceding hours than earlier in the evening, perhaps in response to the lower probability of attracting O. ochracea.
Endogenous glycoconjugates are not associated with filter feeding in mosquito larvae (Diptera: Culicidae)
Authors: Fry Kenneth M.
Published: May 2008

Histochemical techniques were used to determine the origin and possible function of glycoconjugates in the head of larval mosquitoes. Late instars of Aedes aegypti (L.), Aedes implicatus Vockeroth, Culex territans Walker, and Anopheles earlei Vargas were stained with Alcian Blue at pH 0.5, 2.5, and 3.2, aldehyde fuchsin, and periodic acid – Schiff's reagent. Lectins derived from Triticum vulgaris, Bandeiraea simplicifolia, Sophora japonica, Pisum sativum (PSA), and Ulex europaeus were used to determine the composition of the glycoconjugates present in the head of A. aegypti. Additionally, larvae were fed inert Dayglo®particles and stained as above to determine the origin of glycoconjugates observed in the gut. Examination showed that carboxylated and weakly and strongly sulphated glycoconjugates are secreted from what are described here as dorsal and ventral cephalic glands. With the exception of PSA, none of the lectins bound to the glands or their secretion product. Globular and elongate cells in the ventral cephalic gland bound PSA, indicating the presence of α-D-mannose. The secretion product is not used to enhance food capture or handling. Instead, it is hypothesized that these glycoconjugates aid in formation of mouthpart structures or facilitate ecdysis.