bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eggs of spruce grouse dry at a faster rate than those of ruffed grouse
Authors: Bendell James F. , Bendell–Young L.I. 
Published: May 2007

We measured the rate of water loss and pore density of eggs of spruce grouse ( Canachites canadensis canace (L., 1766)) and ruffed grouse ( Bonasa umbellus togata (L., 1766)) from different parts of their range in Ontario. Eggs were dried in enclosed glass jars over Drierite®and in paper trays in open air at room temperature and humidity. Eggs were weighed to the nearest 0.01 g every 2–4 days and the change in mass was measured as water loss. Pores of shells were counted (pores/cm2) in the blunt, middle, and pointed sections of the egg. Eggs of spruce grouse lost water at a faster rate in Drierite®and in open air and had a greater density of pores than eggs of ruffed grouse. Rates of water loss were constant and varied inversely with ambient humidity, with the difference between species greatest in open air. Eggs late in incubation of ruffed grouse dried at a faster rate than those early in incubation in Drierite®. The adaptations of eggs of each grouse to the moisture of the nest may help explain their distribution, density, and habitat and nest-site selections, as well as behavioural aspects of the nesting hen. Both, especially the spruce grouse, may be good indictors of climate change.
Songs of the Savannah Sparrow: structure and geographic variation
Authors: Sung Ha-Cheol , Handford Paul 
Published: May 2007

We investigated song structure and the pattern of geographic variation at the syllable and whole song levels in Savannah Sparrow, Passerculus sandwichensis (J.F. Gmelin, 1789). Songs were recorded for 179 males from eight sample populations distributed along a 230 km transect in southwestern Ontario in 2000. Subsequent analysis included measurement and comparison of structural song features and qualitative analysis of syllable and song type similarity among individuals both within and among populations, by reference to a syllable catalogue based on syllable similarity. Song type sharing within samples was not common, while song dissimilarity significantly correlated with distance among samples. Overall south–north trends appeared in two aspects of quantitative and qualitative characteristics, and the geographic differentiation of Savannah Sparrow songs was gradual, increasing with distance. At a higher level of analysis, two song groups, with qualitatively distinct structures (here termed themes), were identified. These themes showed a clinal intergrade, such that one theme was found in all individuals of the four southern samples, while in the four more northerly samples, the second theme's incidence grew progressively from 20% to 80%. However, birds singing the southern theme in populations dominated by the northern theme nevertheless produced songs that show metrical (frequency and duration) characteristics typical of the northern theme songs from their own population. Cluster analysis based on syllable and song type similarity–dissimilarity between populations linked geographically neighboring populations closely, while populations fell into two main clusters: the three most northerly and the five most southerly populations. The same cluster pattern also appeared within each theme type.
Effects of pH, aluminium, and soft water on larvae of the amphibiansBufo bufoandTriturus vulgaris
Authors: Skei Jon K. , Dolmen Dag 
Published: May 2007

Larval Bufo bufo (L., 1758) and Triturus vulgaris (L., 1758) were exposed to soft water (0.5 mg·L–1Ca2+) experimentally acidified to pH 3.9 to 5.9 and total aluminium concentrations of <10, 150, and 300 µg·L–1. Below pH 4.5 both species experienced increased mortality. The LC50(168 h) for <10 and 150 µg·L–1Al was pH 4.3 and 4.1 for B. bufo and 4.2 and 4.1 for T. vulgaris. However, Al3+increased the survival of both species, which may be due to the contribution of Al3+to the ionic strength. No B. bufo larvae died at pH >4.5, whereas T. vulgaris at higher Al concentrations suffered relatively high mortality at pH 5.1–5.9, where Al occurs mainly as Al(OH)2+and Al(OH)2+. Unlike external gills (T. vulgaris), internal gills (B. bufo) have their own internal environment and are probably better protected against the presence of these toxic Al species in the water. These Al species thus seem to be toxic to T. vulgaris larvae but not to B. bufo. Chloride was seen to be important for survival in water of low ionic strength, since the survival of T. vulgaris larvae, particularly at low Al concentration, increased at pH levels down to pH 4.3 when the water was acidified with HCl.
Timing of Hexagenia (Ephemeridae: Ephemeroptera) mayfly swarms
Authors: Corkum Lynda D. , Ciborowski Jan J.H. , Dolan David M. 
Published: May 2007

Although degree-days can be used to determine when insect emergence begins, peak swarming events in species that exhibit extended emergence periods are difficult to estimate. With the aid of logistic regression, we estimated the probability of adult mayfly swarms (≥50 individuals/m2), occurring on any given night in western Lake Erie, using meteorological data. We sampled adult Hexagenia Walsh, 1863 from 2130 (sunset) to 2300 on 18 dates in 2000 (2 June – 18 July), with the largest numbers retrieved between 13 June and 2 July. Water temperature (20 °C) was the cue to the onset of swarming (subimagos). Highest mean (±SE) density of all Hexagenia adults (subimagos and imagos) was 24 740 ± 8 757 individuals/m2. Overall, 10-fold more imagos (mostly females) than subimagos were attracted to lights. Of the factors examined (air and water temperature, Julian day, dew point, heat index, humidity, moon phase, wind chill, wind direction, wind speed), onshore wind speed (0–9.2 km/h) on calendar dates for which the water temperature exceeded 20 °C was the most significant factor to account for total adult swarms. Eighty-three percent of the 18 swarming events observed in 2000 were correctly predicted. Validity of the model was confirmed with data collected in 2002, during which 5 of 6 swarming events were correctly predicted from the logistic model. Wind promotes adult aggregation at the land–water interface, the effect of which facilitates mating success and predator swamping.
First results on the feeding ecology of the Transcaucasian water shrew Neomys teres (Soricomorpha: Soricidae) from Armenia
Authors: Churchfield Sara , Rychlik Leszek , Yavrouyan Eduard , Turlejski Kris 
Published: May 2007

Microscopic examination of alimentary tracts of 14 Neomys teres Miller, 1908 from a mountainous region in northern Armenia produced the first data on the diet of this almost unknown species of conservation concern. Twenty-three different prey types were distinguished in summer-caught shrews, all of which were invertebrates (14 terrestrial and 9 aquatic in origin). The dominant dietary items were Coleoptera and Diptera adults, Araneae, Opiliones, and Lumbricidae, as well as freshwater crustaceans and Trichoptera larvae. Prey ranged from <3 to >16 mm in length, but those eaten most frequently were 6–10 mm in length. Although N. teres was captured beside streams and rivers, aquatic prey comprised only 27% of the dietary composition. Despite the morphological similarity of N. teres to Neomys fodiens (Pennant, 1771), its foraging niche more closely resembles that of upland populations of Neomys anomalus Cabrera, 1907 and its reliance on aquatic habitats remains equivocal.
Bomb radiocarbon dating calibrates beluga (Delphinapterus leucas) age estimates
Authors: Stewart R.E.A. , Campana S.E. , Jones C.M. , Stewart B.E. 
Published: May 2007

The ages of many mammals are estimated by counting growth layers in tooth sections, yet validation of age estimation techniques using free-ranging mammals has been problematic. Contrary to age estimates for most other animals in which it is assumed that one bipartite growth increment forms annually, beluga whale ( Delphinapterus leucas (Pallas, 1776)) age estimates have been calculated assuming that two growth layer groups (GLGs) form each year. Here we report the age validation for belugas based on date-specific incorporation of atomic bomb radiocarbon into tooth GLGs. Radiocarbon assays of dentinal layers formed in belugas harvested between 1895 and 2001 indicated that radiocarbon from atmospheric testing of nuclear weapons was incorporated into growing teeth and retained for the remaining life of the animal. Comparison of age determined by bomb radiocarbon with age determined by GLG counts indicated that GLGs form annually, not semiannually, and provide an accurate indicator of age for belugas up to at least 60 years old. Radiocarbon signatures of belugas were temporally and metabolically stable and were apparently derived more from the radiocarbon content of their prey than from water. Our understanding of many facets of beluga population dynamics is altered by the finding that this species lives twice as long as previously thought.
Stress and parasitism of white-footed mice (Peromyscus leucopus) in dry and floodplain environments
Authors: Brown T.T. , Fuller C.A. 
Published: May 2007

We hypothesized that flooding represents an environmental stressor that might affect the corticosterone levels, parasite prevalence, and life history of small mammals living in floodplain environments. We compared populations of white-footed mice ( Peromyscus leucopus (Rafinesque, 1818)) on floodplains and dry areas. We found more males on floodplains (p = 0.008) and more females on dry areas (p = 0.005). There were no differences in mass (p > 0.05) or intestinal parasite prevalence (p = 0.665) between dry and floodplain habitats, but bot fly larvae were significantly more prevalent in males living on floodplains (p = 0.043). Floodplain animals had significantly higher levels of corticosterone than dry-area animals in fall, and lower levels in summer (F[1,20] = 4.483, p = 0.047). In addition, we found that animals with intestinal parasites had higher levels of corticosterone than those that were without parasites (p = 0.014) or that harbored bot fly larvae (p = 0.001). Floodplains seem to be harsher environments than dry areas, but this may be a result of differences in habitat rather than a direct result of flooding.
Site fidelity, migratory behaviour, and spatial organization of female isards (Rupicapra pyrenaica) in the Pyrenees National Park, France
Authors: Crampe J.-P. , Bon R. , Gerard J.-F. , Serrano E. , Caens P. , Florence E. , Gonzalez G. 
Published: May 2007

We studied from 1993 to 2002 the spatial organization of visually marked females in an isard ( Rupicapra pyrenaica Bonaparte, 1845) population in the Pyrenees National Park. In winter, all individuals were concentrated within the same 3.7 km2 refuge area. In summer, two patterns of space use were recorded: sedentary females (n = 33; 52.2%) remained within the refuge area, whereas migrating females (n = 29; 46.8%) summered outside the refuge area, at a horizontal distance of 1.4–9.2 km and 300–800 m higher in elevation than their winter ranges. Females were faithful to their seasonal ranges. The population was organized in well-defined spatial units in summer. This organization was roughly preserved in winter, despite the spatial concentration of the individuals by this season. The resulting spatial clustering might reduce spatial competition and pathogenic contamination between groups, allowing the maintenance of high population density. The appearance of a migratory pattern occurred probably as a result of the protected status of the species, which allowed the population to increase. Some individuals dispersed as a result of the population density increase. The two recorded patterns of space use likely arose from spatial attachment and social affinity that developed in the first years of a female’s life, and could explain the coexistence of the two spatial patterns.
Wildfire effects on home range size and fidelity of boreal caribou in Alberta, Canada
Authors: Dalerum Fredrik , Boutin Stan , Dunford Jesse S. 
Published: May 2007

Wildfire can rapidly alter the forage availability for boreal ungulates such as woodland caribou ( Rangifer tarandus caribou Gmelin, 1788). Since fire decreases available lichens, a crucial food source for caribou, it may be an important determinant of caribou range use and demography. Here we examined whether wildfire affected range use, habitat selection, and basic demographic variables of boreal caribou in three regions in northern Alberta, Canada. Contrary to expectations, caribou showed no change in home range sizes nor did they shift their home ranges in the years following fires, despite having up to 76% of individual home ranges burned. Within home ranges, caribou preferred stands >50 years old and avoided stands <50 years old, but the extent of home range burned did not affect habitat selection in the year after fire. Although fire does not seem to directly affect the spatial distribution of Alberta caribou, the generation of younger seral stages may affect how caribou distribute within their annual ranges. However, this did not appear to affect population demographics, as fire did not affect annual mortality or fecundity. Boreal caribou in Alberta may be resilient to the effects of fire owing to large home ranges.
Physiology of the ciliate Orchitophrya stellarum and its experimental infection of Leptasterias spp.
Authors: Stickle William B. , Kozloff Eugene N. , Story Shana 
Published: May 2007

Orchitophrya stellarum Cépède, 1907 is a facultative ciliate that parasitizes male asteriid sea stars in the North Atlantic and Pacific oceans. The ciliate also exists in seawater where it feeds on bacteria associated with tissue or yeast. This study is designed to determine the tolerance, growth rate, contractile vacuole activity, and infectivity to Leptasterias Verrill, 1866 spp. as a function of the sea star’s reproductive cycle stage. The tolerance range of O. stellarum in seawater containing bacteria is 2 practical salinity units (PSU) at 8 °C and 12.5 PSU at 25 °C; the ciliate tolerated a temperature range of 3–27 °C at 30 PSU. Ciliate population growth is most rapid at 24 °C and is minimal at 3 and 27 °C at 30 PSU. The ciliate’s contractile vacuole cycle frequency increases at low salinity, indicating increased water volume regulation as a function of decreased salinity. Unparasitized male Leptasterias spp. can be infected experimentally by injection of a culture of O. stellarum into the rays or from a culture in ambient seawater only when the testes are at full size, but the ciliates do not invade ovarian tissue. The normal path of entry of O. stellarum into the testes of reproductively mature male sea stars probably takes place through gonopores.
Regulation compliance by vessels and disturbance of harbour seals (Phoca vitulina)
Authors: Johnson Amber , Acevedo-Gutiérrez Alejandro 
Published: May 2007

The US National Oceanic and Atmospheric Administration established a buffer zone around marine mammals to prevent harassment. The buffer zone varies by species listing status and by geographic area. However, it is unknown the extent to which vessels comply with these buffer zones. We selected harbor seals ( Phoca vitulina L., 1758) as a case study to describe compliance with the buffer zone. We conducted land-based observations from Yellow Island, Washington State, in a geographic area where the buffer zone is 91 m (100 yards), to estimate vessel distance from hauled-out seals and to evaluate seal response. We recorded 85.7% of kayaks, 57.1% of stopped powerboats, and 4.6% of passing powerboats violating the buffer zone. Seals were disturbed by kayaks and stopped powerboats at distances >91 m from the haul-out sites but not by moving powerboats ≤91 m from the sites. Hence, compliance of the buffer zone varied with vessel type and vessel activity. We suggest that a larger buffer zone for vessels lingering around the haul-out sites and enforcement of the buffer zone will minimize seal disturbance.
Mountain beaver home ranges, habitat use, and population dynamics in Washington
Authors: Arjo W.M. , Huenefeld R.E. , Nolte D.L. 
Published: May 2007

The mountain beaver ( Aplodontia rufa (Rafinesque, 1817)), endemic to western North America, is the only extant member of the family Aplodontidae. Limited information on movements and habitat use throughout the species’ range is available. We radio-collared 41 mountain beavers to determine home ranges, dispersal, habitat use, and population densities on two managed forest sites in coastal Washington. Both sites were recently harvested for timber. The Donovan site (16.6 ha) was treated with herbicide before seedling planting and the Sylvia site (8.9 ha) was not treated. Mountain beaver home ranges (Donovan: 4.18 ± 0.81 ha; Sylvia: 1.39 ± 0.4 ha) were greater than previously reported in the literature (0.02–0.2 ha). Home ranges (P = 0.009) and core use areas (P = 0.05) on the herbicide-treated Donovan site were larger than those observed on the untreated Sylvia site. Mountain beaver population density declined from 2002 (n = 16) to 2003 (n = 8) on the Donovan site, and reinvasion onto the site after removal trapping was low (n = 7). Population density more than doubled on the Sylvia site from 2002 (n = 21) to 2003 (n = 55), and reinvasion was greater (n = 27) than observed at Donovan. In addition, we documented habitat characteristics centered at 9 Donovan and 10 Sylvia nest locations. Sites were similar in most habitat characteristics, but the Sylvia site had more herbaceous forbs, stumps, and woody debris. Our findings suggest that mountain beaver populations and home ranges are affected by availability of forage, such as herbaceous forbs, after herbicide treatment, as well as by availability of woody cover.
Do δ15N and δ13C values of feces reflect the isotopic composition of diets in small mammals?
Authors: Hwang Y.T. , Millar J.S. , Longstaffe F.J. 
Published: May 2007

The stable isotope composition of carbon and nitrogen in feces can be a useful tool for reconstructing diet. To examine whether the isotopic composition of feces reflect those of diet, we determined the fractionation of 15N and 13C along the digestive tracts of several species of small mammals. There were significant differences in the δ15N values of digesta in different compartments of the gastrointestinal (GI) tract, with consistent enrichment of 15N in the stomach, intestine, and cecum, and the depletion of 15N in the colon (i.e., feces). Although feces had lower δ15N values than digesta in the cecum, feces of small mammals were significantly more enriched in 15N (by ~2.5‰) than diet. The mechanisms causing this enrichment in the GI tract may arise from the operation of different biochemical pathways within the different GI compartments. The stable carbon isotope composition of digesta in small mammals were similar along the GI tract, but the δ13C values of digesta and feces were significantly lower than reported previously for large ungulates (–3.5‰ vs. –0.5‰). The δ15N and δ13C values of feces did not directly reflect the isotopic compositions of these mammals’ diet. Our data offer evidence for variations in isotopic discrimination effects. This variation can probably be ascribed to metabolism of different body sizes of mammals and the complexities linked with digestive physiology of herbivores.
Transcranial Magnetic Stimulation in a Finger-tapping Task Separates Motor from Timing Mechanisms and Induces Frequency Doubling
Authors: Levit-Binnun Nava , Handzy Nestor Z. , Peled Avi , Modai Ilan , Moses Elisha 
Published: May 2007

Abstract
We study the interplay between motor programs and their timing in the brain by using precise pulses of transcranial magnetic stimulation (TMS) applied to the primary motor cortex. The movement of the finger performing a tapping task is periodically perturbed in synchronization with a metronome. TMS perturbation can profoundly affect both the finger trajectory and its kinematics, but the tapping accuracy itself is surprisingly not affected. The motion of the finger during the TMS perturbation can be categorized into two abnormal behaviors that subjects were unaware of: a doubling of the frequency of the tap and a stalling of the finger for half the period. More stalls occurred as the tapping frequency increased. In addition, an enhancement of the velocity of the finger on its way up was observed. We conclude that the timing process involved in controlling the tapping movement is separate from the motor processes in charge of execution of the motor commands. We speculate that the TMS is causing a release of the motor plan ahead of time into activation mode. The observed doubles and stalls are then the result of an indirect interaction in the brain, making use of an existing motor plan to correct the preactivation and obtain the temporal goal of keeping the beat.
Stronger Synaptic Connectivity as a Mechanism behind Development of Working Memory-related Brain Activity during Childhood
Authors: Edin Fredrik , Macoveanu Julian , Olesen Pernille , Tegnér Jesper , Klingberg Torkel 
Published: May 2007

Abstract
The cellular maturational processes behind cognitive development during childhood, including the development of working memory capacity, are still unknown. By using the most standard computational model of visuospatial working memory, we investigated the consequences of cellular maturational processes, including myelination, synaptic strengthening, and synaptic pruning, on working memory-related brain activity and performance. We implemented five structural developmental changes occurring as a result of the cellular maturational processes in the biophysically based computational network model. The developmental changes in memory activity predicted from the simulations of the model were then compared to brain activity measured with functional magnetic resonance imaging in children and adults. We found that networks with stronger fronto-parietal synaptic connectivity between cells coding for similar stimuli, but not those with faster conduction, stronger connectivity within a region, or increased coding specificity, predict measured developmental increases in both working memory-related brain activity and in correlations of activity between regions. Stronger fronto-parietal synaptic connectivity between cells coding for similar stimuli was thus the only developmental process that accounted for the observed changes in brain activity associated with development of working memory during childhood.