bluuebunny/crossref_metadata_2025 huggingface dataset:
Review of Nearctic genera of Euderinae (Hymenoptera: Eulophidae), with descriptions of two new species of Allocerastichus Masi, and redescription of Carlyleia marilandica Girault
Authors: Coote Lonny D.
Published: July 2008

Nearctic genera of Euderinae (Hymenoptera: Eulophidae) are reviewed, and diagnostic characters of the subfamily are discussed. Six genera, Acrias, Allocerastichus, Astichus, Carlyleia, Euderus, and Hubbardiella, are recognized from the Nearctic region. Notes are provided on nomenclature, taxonomy, geographic distribution, and natural history for each genus. Six generic names are placed in synonymy: Moureisca De Santis, Urban, &Graf, Balinia Hedqvist, Durinia Hedqvist, and Oinia Hedqvist as junior synonyms of Acrias, and Cortesiella De Santis and Gimlia Hedqvist as junior synonyms of Allocerastichus. Two specific names are placed in synonymy: Astichus (Astichus) notus Yoshimoto as a junior synonym of A. (A.) polyporicola Hedqvist and Euderus (Euderus) viridilineatus Yoshimoto as a junior synonym of E. (E.) verticillatus (Ashmead). The genus Allocerastichus is recorded from the Nearctic region for the first time, based on A. bicarinatus sp.nov. (type locality: Louisa County, Virginia, U.S.A.) and A. tricarinatus sp.nov. (type locality: Jackson County, North Carolina, U.S.A.). The female of Carlyleia marilandica Girault is redescribed, and the male is described for the first time. Two subgenera of Euderus are recognized: Euderus s.str. and Euderus (Secodelloidea). The genus Parasecodella, represented in the New World by an undescribed Nearctic species, is probably synonymous with Euderus; it may constitute a third subgenus. Further examination of species of Parasecodella and Euderus s.l. should be done before such a classification is made. The difficulty of recognizing Hubbardiella as a euderine, based on the number of distinct metasomal tergites, is discussed.
Interspecific differences in whistles produced by inshore dolphins in Moreton Bay, Queensland, Australia
Authors: Schultz Kenneth W. , Corkeron Peter J.
Published: July 2008

The sounds produced by bottlenose dolphins, Tursiops truncatus, and Indo-Pacific humpback dolphins, Sousa chinensis, were recorded on 11 days from 3 April to 13 August 1990 in Moreton Bay, eastern Australia. Twelve hours and 34 minutes of sound were recorded. The physical structure of whistles was described using a variable for duration and seven variables for frequency. Data were subjected to principal components analysis (PCA) and canonical discriminant analysis (CDA). PCA demonstrated the range of whistle contours recorded. CDA demonstrated differences in the whistles between species. Humpback dolphin whistles differed in shape (frequency modulation) and were generally of shorter duration and higher overall frequency than those of bottlenose dolphin whistles.
A review of the distribution and taxonomy of Myotis keenii and Myotis evotis in British Columbia and the adjacent United States
Authors: Jong Constantinus G. van Zyll de , Nagorsen David W.
Published: July 2008

Myotis keenii and M. evotis are sympatric in coastal areas of British Columbia and Washington. Some individuals are morphologically intermediate and cannot be identified confidently. This has raised questions about the correct identification of specimens collected in the area of overlap and the systematic relationship of the two taxa. Multiple discriminant function analysis of 12 cranial and 5 body measurements demonstrated the presence of two morphological groups in the area. The results suggest morphological convergence of the two taxa in Washington and that a number of individuals from western Washington were morphometrically intermediate. The intermediates were provisionally interpreted as representing overlapping intraspecific variation rather than intergradation between the taxa. Analysis of molecular data is required to resolve the systematics of these taxa.
Enzyme activity profiles in an overwintering population of freeze-avoiding gall moth larvae, Epiblema scudderiana
Authors: Joanisse Denis R. , Storey Kenneth B.
Published: July 2008

The maximal activities of enzymes of intermediary metabolism, notably glycolysis, the hexose monophosphate shunt, and polyol cryoprotectant synthesis were measured over a winter season in freeze-avoiding larvae of the gall moth Epiblema scudderiana. Dynamic changes in enzyme activities were found to reflect metabolic events associated with different and changing requirements of the larvae for survival as winter progressed and ended. Activities of enzymes associated with the cryoprotectant glycerol indicated two possible pathways for its synthesis: (1) glyceraldehyde-phosphate → glyceraldehyde → glycerol via glyceraldehyde phosphatase and NADPH-linked polyol dehydrogenase, or (2) dihydroxyacetonephosphate → glycerol-3-phosphate → glycerol via glycerol-3-phosphate dehydrogenase and glycerol-3-phosphatase. Glycogen phosphorylase activation in the fall supplied carbon equivalents required for glycerol synthesis from glycogen. Hexose monophosphate shunt enzyme activity was high, reflecting the role of this pathway in supplying NAD(P)H for glycerol synthesis. Spring clearance of glycerol appeared to occur via polyol dehydrogenase and glyceraldehyde kinase. Increasing fructose-bisphosphatase activity into late winter and spring was found to increase the gluconeogenic potential needed for cryoprotectant removal. Increased activity of glycerol-3-phosphate dehydrogenase in the spring, possibly reflecting increased α-glycero-phosphate shuttle activity, may be key to the removal of reducing equivalents generated from glycerol removal.
Methods of scent marking in the domestic cat
Authors: Feldman Hilary N.
Published: July 2008

Carnivores use various scent-marking methods. Semi-feral domestic cats (Felis silvestris catus) were observed to use the same means as their wild counterparts. Adult males performed most urine spray marking. Cats scratched tree bark, producing a visual mark, and probably used trees both as markers and for claw sharpening. Most scratching trees were located along frequently used paths rather than along territorial boundaries or scattered randomly throughout a home range. Bark consistency affected the tree species that were scratched, with soft bark preferred. Although deposition of faeces and urine was recorded, there was no clear evidence for their use as territorial markers; cats primarily eliminated away from the core area of the home range. Most faeces were buried, although exposed deposits were also observed. Cats also rubbed against objects, probably using glandular secretions from the face and tail areas to scent mark. Males rubbed objects more than females, and males scent marked more. Individual males may use different means of scent marking. Scent marking in this study supports the idea that cats do not defend territories, instead patrolling and reinforcing marks throughout a looser home range. The suggestion has been made that different forms of marking may serve separate signalling functions.
Low chloride and high short-chain carboxylic acid concentrations in extracellular fluid: a common physiological feature of the Hirudinea
Authors: Nieczaj Rolf , Zerbst-Boroffka Irene
Published: July 2008

The ionic blood composition of extracellular fluid was studied in 11 species of Hirudinea from various habitats (marine, limnic, semiterrestrial) and families. The major cation found was sodium. Chloride concentrations, however, were low in relation to cations. Extracellular concentrations of short-chain carboxylic acids (with malate as the most abundant acid) were responsible for a significant proportion of total anionic equivalents. An apparent anion deficit in limnic and semiterrestrial species and a pronounced gap in the osmolytes in a marine piscicolid suggest the presence of unidentified extracellular constituents. Irrespective of their systematic position and habitats, the investigated Hirudinea all share the physiological feature of low extracellular chloride and high short-chain carboxylic acid concentrations, which distinguishes them from the Polychaeta.
Sex-specific and latitudinal variance in postnatal growth of the Subantarctic fur seal (Arctocephalus tropicalis)
Authors: Bester Marthán N. , Jaarsveld Albert S. Van
Published: July 2008

Parameter estimates reflecting age-specific growth of Subantarctic fur seals (Arctocephalus tropicalis) on Gough Island were fitted to three sigmoidal (Gompertz, logistic, and von Bertalanffy) growth curves. With a few exceptions, the logistic fit provided the best mathematical approximation of postnatal growth in fur seals from Gough Island, although all fits were significant. Standard length is a better reflection of age-specific changes in size than mass, which displayed considerable variance. Growth was characterized by marked sexual dimorphism. Interisland comparisons of body size from throughout the geographic range of the species suggested a latitudinal graded difference in adult body size, with the largest animals occurring at low-latitude Amsterdam Island and the smallest at Marion Island, which lies just north of the Antarctic Polar Front. These growth and body-size estimates can be used for monitoring the effects of population or ecosystem changes on fur seal productivity, but significant standardization of data collection procedures need to be introduced.
Fall condition factor and temperature influence the incidence of metamorphosis in sea lampreys, Petromyzon marinus
Authors: Holmes John A. , Youson John H.
Published: July 2008

Larval sea lampreys of immediate premetamorphic size (at least 120 mm and 3.0 g) were subjected to ambient or constant 21 °C temperature regimes for 9 months to investigate the influence of temperature and a fall condition factor (CF) of 1.50 or greater on the incidence of metamorphosis the following summer. The incidence of metamorphosis was 53% in the ambient temperature regime (29/55) and only 2% (1/55) in the constant temperature regime. About 64% (7/11) of the presumptively metamorphic larvae in the ambient temperature regime entered metamorphosis compared with 10% (1/10) in the constant temperature regime. Our predictions of metamorphosis based on CF were consistent with the observation that seven presumptively metamorphic larvae (CF ≥ 1.50) metamorphosed in the ambient temperature regime and that there was no metamorphosis among presumptively nonmetamorphic larvae in the constant temperature regime. Significantly more presumptively nonmetamorphic larvae in the ambient regime entered metamorphosis and fewer presumptively metamorphic larvae (CF < 1.50) metamorphosed in the constant temperature regime than expected. We attribute this response to the effects of temperature on metabolic processes. Larval sea lampreys of the appropriate size (≥ 120 mm and ≥ 3.0 g) with a CF of 1.50 or greater in the fall will usually enter metamorphosis the following July, but the accuracy of these predictions may be improved in some populations by using an empirically determined CF criterion that reflects seasonal or population differences in mass–length relationships.
End-tidal gas composition is not correlated with episodic breathing in hibernating ground squirrels
Authors: Garland Rhonda J. , Milsom William K.
Published: July 2008

During hibernation, the breathing pattern of the golden-mantled ground squirrel (Spermophilus lateralis) consists of short episodes of breathing separated by pauses ranging in length from less than 1 min to greater than 30 min. Computerized tomography scans of two hibernating animals during apnea indicated that the glottis was closed and that apneic oxygenation could not occur. Analysis of end-tidal gas composition, indicative of arterial blood gas composition, revealed no clear thresholds in gas composition for initiating or terminating episodes of breathing. Over the course of a breathing episode, however, O2 extraction fell exponentially, while CO2 excretion fell in a linear fashion. The breathing episode terminated at the point where O2 extraction asymptoted, suggesting that the length of the episode was just sufficient to repay the O2 debt that accumulated during the preceding period of apnea. The oxidative cost of the events associated with breathing episodes in these animals was calculated to be approximately 90% of the total metabolic rate during hibernation. This suggests that metabolic rate is not constant during hibernation but varies in a cyclic fashion associated with the breathing pattern. It further suggests that although the levels of blood gases play a key role in establishing the total level of ventilation, the cyclic variations in their composition, associated with periods of apnea and eupnea, do not by themselves initiate or terminate breathing episodes.
Gill function in the amphipod Megalorchestia (Orchestoidea) californiana (Brandt, 1851) (Crustacea)
Authors: Spicer John I. , McMahon Brian R.
Published: July 2008

In the amphipod Megalorchestia (Orchestoidea) californiana immersed in full-strength seawater at 15 °C, gill excision resulted in a decrease in CO2 and NH4+ excretion but not in O2 uptake. When the temperature was increased to 25 °C, however, there was a significant decrease in all gas exchange as a result of gill excision. Gill excision also resulted in a decrease in haemolymph pH and [Formula: see text] at both experimental temperatures. Furthermore, pretreatment of large individuals with the carbonic anhydrase inhibitor acetazolamide resulted in a significant increase in haemolymph pH, [Formula: see text], and total CO2 regardless of whether or not gills were present. There was, however, a significant increase in haemolymph [Formula: see text] in treated individuals as a result of gill excision. This study has shown that the coxal gills of this talitrid amphipod were involved in gas and ion exchange (particularly CO2 and NH4+). It is unlikely, however, that the gills were the only sites of exchange.
Occurrence of chironomid larvae (Paratanytarsus sp.) as commensals of dreissenid mussels (Dreissena polymorpha and D. bugensis)
Authors: Ricciardi Anthony
Published: July 2008

Up to 38% of zebra mussels (Dreissena polymorpha) and 10% of quagga mussels (Dreissena bugensis) collected from the upper St. Lawrence River in July 1993 were invaded by larvae of the tanytarsine chironomid Paratanytarsus sp. Third- and fourth-instar larvae were found living in the mantle cavity around the gills, gonads, and siphonal tissues. The larvae were never observed feeding on these tissues, and no tissue damage was detected. Most frequently, a single Paratanytarsus sp. larva occurred in a mussel; otherwise, two to six larvae were found. Invaded mussels were significantly larger than co-occurring non-invaded mussels. No chironomid larvae were found in young-of-the-year dreissenids. This is the first case of a large-scale endosymbiotic association, apparently a form of inquiline commensalism, between chironomid larvae and dreissenid mussels. Paratanytarsus sp. larvae also occurred in unionid bivalves (Elliptio complanata, Lampsilis radiata, Anodonta cataracta), but at relatively lower frequencies.
Costs of escalated territorial defence in red squirrels
Authors: Stuart-Smith A. Kari , Boutin Stan
Published: July 2008

The costs of escalated territorial defence have not been well-documented, although in theoretical studies they are often assumed to be high. We manipulated territorial defence in red squirrels (Tamiasciurus hudsonicus) to assess the costs of territorial disputes in terms of energy, reproductive status, and predation. Feeders containing sunflower seeds were used to manipulate foraging behaviour and induce territorial disputes. Experimental squirrels displayed dramatically higher rates of territorial behaviours in response to feeders, and while there was no difference in survival between experimental and control squirrels, in 4 of the 17 disputes territory owners lost their territories. All 3 females that did so suffered reproductive costs. Territorial disputes were won by the heavier squirrels in all 12 cases where contestants were of different masses, but where the contestants were of similar masses (4 of 5 cases), territory owners were more likely to win.
Body size and sex ratio in emergent stonefly nymphs (Isogenoides olivaceus: Perlodidae): variation between cohorts and populations
Authors: Haro Roger J. , Edley Kay , Wiley Michael J.
Published: July 2008

The ecological significance of pattern in animal-size distribution has been receiving increased scrutiny in studies of population regulation and individual energetics. However, few studies have assessed differences in size variation between sequential generations or adjacent populations. Annual variation in body size and sex ratio of emergent perlodid stonefly nymphs, Isogenoides olivaceus (Frison) (Plecoptera: Perlodidae), were examined in populations from two Michigan mesic groundwater rivers. Final nymphal body size was estimated from sex-specific length to mass regression relationships using exuviae collected from each site. Sexual size dimorphism accounted for much of the intraspecific size variation within both populations and cohorts: females were larger ([Formula: see text]) than males ([Formula: see text]). Males showed less size variation than females; unlike those for females, size distributions for males were significantly skewed. Secondary sex ratios were female biased in both populations and all cohorts and ranged between 59.1 and 72.8%. Female sex bias increased with relative male size in both populations.
Niche relationships within a guild of ungulate species in Yellowstone National Park, Wyoming, following release from artificial controls
Authors: Singer Francis J. , Norland Jack E.
Published: July 2008

Niche relationships and diet overlaps were compared among elk (Cervus elaphus), bison (Bison bison), bighorn sheep (Ovis canadensis), mule deer (Odocoileus hemionus), and pronghorn antelope (Antilocapra americana) between 1967–1970 and 1986–1988, a period when total ungulate numbers nearly tripled on Yellowstone's northern range. Ungulate species ratios on Yellowstone's northern winter range during the latter period were 100 elk : 10 mule deer : 3 bison : 2 pronghorns : 1 bighorns. Elk numbers were positively correlated to bison, mule deer, and pronghorn numbers (r2 = 0.76, 0.97, and 0.48, respectively, P < 0.01). Few other changes in habitat use or habitat overlap occurred, and diets for only 2 of the 10 species pairs, elk-bighorn (Spearman's rank order coefficient (RHO) = 0.55, P < 0.05) and mule deer – pronghorn (RHO = 0.64, P < 0.05), were significantly associated with each other. Bison consumed more grass and fewer sedges, mule deer more fringed sage (Artemisia frigida) and more rabbit-brush (Chrysothamnus spp.), and bighorn sheep more grasses and fewer sedges, while pronghorns ate less saltsage (Atriplex nuttalli) but more big sagebrush (Artemisia tridentata) during 1986–1988 than during 1967–1970. Bison expanded their range and bison and bighorn sheep used a wider variety of habitats. We found little evidence of change in competitive interactions between ungulate species. A few diet and habitat overlaps increased, the opposite of the prediction from the competitive exclusion principle amongst species, suggesting that intraspecific competition was more important. Several explanations are proposed for the lack of changes in niche relationships during a period of near tripling in density of the ungulate guild.
Influence of season, sex, and site availability on fisher (Martes pennanti) rest-site selection in the central hardwood forest
Authors: Kilpatrick Howard J. , Rego Paul W.
Published: July 2008

We monitored 20 adult fishers (8 males, 12 females) to investigate the effects of season, sex, and site availability on rest-site selection by fishers at the southern extent of their range. Data on rest-site locations (n = 219) and random sites (n = 194) were collected from December 1989 through February 1991. Fishers rested in hardwood, softwood, and mixedwood forest types in proportion to their availability in summer; however, hardwoods were used less than expected in winter. Fishers used nests, cavities, and burrows in proportion to their availability in winter. In summer, however, nests were selected twice as often as expected, cavities were used less than expected, and burrows were not used. Male fishers tended to use larger cavity trees and mixed forest stands more often than females did. In winter, fishers were not restricted to coniferous forest types, as occurs at the northern extent of their range, because moderate snow depths did not restrict movement and prey may have been more available in other forest types. Fishers appeared to select rest-site types most suitable for thermoregulation and obtaining prey. Trees with diameter at breast height ≥ 32 cm may provide cavities for rest sites in hardwood-dominated forests.
How do sexual differences in growth and maturation interact to determine size in northern and southern painted turtles?
Authors: St. Clair Robert , Gregory Patrick T. , Macartney J. Malcolm
Published: July 2008

Widely distributed animals often show considerable differences in growth and maturation both between sexes and among populations. We compared growth and maturation between the sexes in the painted turtle (Chrysemys picta) at the northern limit of its range and related these differences to patterns observed in southern populations. In British Columbia, females grow faster and mature later than males, and as a consequence, are both larger and older than males at maturity. Northern individuals of both sexes show greater annual growth than populations farther south, despite a shorter growing season. Northern males may mature at a similar age to those in the south but northern females mature later than those in the south and this, coupled with faster growth, results in larger size at maturity. Because of constraints on the number of clutches that may be successfully incubated per year at a higher latitude, northern females reproduce at most once per year, whereas southern females can produce several clutches over a summer. Therefore, delayed maturity and faster growth may be favoured in northern females so that they may produce larger clutches at a necessarily lower annual frequency.
Winter habitat selection by lynx and coyotes in relation to snowshoe hare abundance
Authors: Murray Dennis L. , Boutin Stan , O'Donoghue Mark
Published: July 2008

We examined the relationship between winter habitat selection among lynx (Lynx canadensis) and coyotes (Canis latrans) and relative snowshoe hare (Lepus americanus) abundance by tracking in snow during three winters. Hare numbers were higher in dense spruce (Picea glauca) than in other habitats in 1987–1988, and both predator species selected that habitat in that year. In 1988–1989, hare distribution was similar among habitats, and both predators used spruce habitats relative to their availability. In 1989–1990, hare numbers were also similar among habitats, and lynx used spruce habitats according to availability, whereas coyotes selected dense spruce. Hares were the main prey of both species, and the distribution of hares chased and killed by lynx was similar to that predicted by habitat use. Lynx hunting success was also similar among habitats. In comparison, coyotes chased and killed more hares than expected and had higher hunting success in dense spruce. Snow was shallower and harder in all spruce habitats used by coyotes than in those travelled by lynx. This suggests that coyotes were more selective of snow conditions than lynx, probably as a result of their high foot-load (ratio of body mass to foot area) relative to that of hares. Coyotes scavenged more often than lynx, but neither species seemed to select habitats on the basis of carcass availability. We concluded that high hare densities influenced selection of dense spruce by both species in 1987–1988, and that coyotes may also have chosen habitats on the basis of hunting success and snow conditions.
The ultrastructure of the sperm and motile spermatozeugmata released from the freshwater mussel Anodonta grandis (Mollusca, Bivalvia, Unionidae)
Authors: Lynn John W.
Published: July 2008

Mature sperm are released from Anodonta grandis as multiple spherical spermatozeugmata, which are complexes measuring 40–50 μm and containing up to 2800 sperm when fully populated. The 1.5 × 4.0 μm cylindrical sperm head is anchored in the spherical spermatozeugma periphery, with the 35 μm long flagella projecting perpendicular to the surface. Rotational and progressive motility is achieved by an apparently asynchronous but sequential flagellar beat. An acellular 80-nm lamina around the spherical spermatozeugma encircles a central fluid-filled sphere called the globe. Each sperm head is embedded in a chamber formed by extensions of the 80-nm lamina and in contact with the sperm plasmalemma in a flagellar collar posterior to the 5 mitochondria at the base of the sperm nucleus. A proximal centriole located in a fossa in the nucleus base is connected to a distal centriole by a dense amorphous matrix. The distal centriole is locked to the flagellar collar via 9 striated, bifurcated pericentriolar processes. The anterior part of the sperm contains an acrosome-like region containing 0.1 μm diameter membrane-bound vesicles. The spermatozeugma complexes may survive up to 24 h and may serve to transport sperm to the gill chamber of the female mussel.
Larval diapause, size, and autogeny in the mosquito Aedes togoi (Diptera, Culicidae) from tropical to subarctic zones
Authors: Sota Teiji
Published: July 2008

Larval development of nine populations of Aedes togoi (Theobald) collected from tropical to subarctic zones was studied under photoperiods of 16 h light (L) : 8 h dark (D) and 10 h L : 14 h D at 15 °C. Larvae that did not pupate within 60 days were regarded as diapausing. Larval diapause did not occur in all populations at 16 h L : 8 h D. At 10 h L : 14 h D, four populations from tropical and subtropical zones included no diapausing larvae, whereas 60–99% of individuals from five northern populations of Japan and Canada were diapausing. Adult size increased with latitude of original locality. The proportion of autogenous females among those developed at 16 h L : 8 h D and 15 °C decreased with original latitude, whereas that among females from nondiapausing larvae reared at 10 h L : 14 h D and 15 °C was consistently high throughout the latitudes. At 10 h L : 14 h D and 15 °C, larval developmental characters of F1 and F2 hybrids between Malaysian (no diapause) and Japanese (diapausing) populations were intermediate between the parental populations. Expression of autogeny of the hybrids was similar to that of the Malaysian strain. A Canadian population, which might have been introduced from Japan, showed developmental traits similar to those of two populations from temperate Japan.
Genetic colony and population structure of the ant Leptothorax cf. canadensis
Authors: Heinze Jürgen
Published: July 2008

The small myrmicine ant Leptothorax cf. canadensis is one of the most common ants in boreal coniferous forests in eastern North America. Throughout its range, colonies may contain several fertile queens, i.e., the species is facultatively polygynous. According to estimates of relatedness from allozyme data, the number of queens does not reliably reflect the number of matrilines actually present within the nests, probably as a result of frequent changes in the number of queens per colony. Electromorph frequencies of two variable enzyme loci did not differ significantly between samples of populations from various localities, including an isolated population in southern New Hampshire. It appears that large population size in ants of the genus Leptothorax counteracts random genetic drift. The life history of L. cf. canadensis is discussed in respect of the genetic data.
Depletion of lipid, lean, and ash masses in food-restricted American black ducks
Authors: Morton John M. , Kirkpatrick Roy L. , Howerter David W. , Eason Thomas H. , Long Christine M.
Published: July 2008

We investigated the rate and order of depletion of lipid depots and other body components in American black ducks (Anas rubripes) responding to food restriction. Forty-one hatching-year ducks were placed on one of four diets to induce high variability in body composition. Regression analyses suggest that for every 1-g decrease in body mass, lipids decreased 0.53 g, water decreased 0.36 g, ash-free nonlipid dry mass (NLDM) decreased 0.05 g, and ash decreased 0.02 g. However, depletion rates were not uniform among lipid sources. Both lipid mass and lipid depletion rate were ranked in descending order: subcutaneous, carcass, omental, and visceral. Despite disproportionately low depletion rates, intraperitoneal depots were depleted before subcutaneous or carcass lipids. We also found evidence of a sexual difference in endogenous nutrient utilization by American black ducks in response to food restriction. Males reduced NLDM (mostly breast muscle), visceral lipids, and subcutaneous lipids concomitantly. In contrast, females did not utilize NLDM but depleted visceral and subcutaneous lipids at rates 146–175% higher than males. These data suggest that relationships between depot and total body lipid masses are not necessarily uniform. Furthermore, it may not be possible to apply some measures of physiological condition equitably to both sexes of Anatinae.
Nest distribution, site selection, and brooding in the five-lined skink (Eumeces fasciatus)
Authors: Hecnar Stephen J.
Published: July 2008

I studied nest site selection and brooding behaviour in a population of Eumeces fasciatus at Point Pelee National Park, Ontario, Canada, in 1990, 1991, and 1992. Females preferred large, moderately decayed logs as nest sites. Multiple and communal nests were common in all years even though suitable nest sites were not limited. Soil moisture appeared to be an important physical factor. Soil moisture was higher at nests than at other sites or in the ambient environment. Females varied brooding position according to the moisture level. Brooding positions with high body to egg contact were observed with lower moisture levels, and low-contact positions were observed with higher moisture levels. Females did not space eggs or vary cavity size to control moisture, but they may have moved nests vertically. The woody debris that female skinks select as nest sites provide a relatively constant microclimate for egg development. The aggregated pattern of nest distribution suggests a possible response to predation pressures.
Black duck – mallard behavioural interactions in relation to hybridization
Authors: D'Eon Robert G. , Seymour Norman R. , Boer Arnold H.
Published: July 2008

Black duck (Anas rubripes) numbers have declined over the past several decades in conjunction with a gradual eastward range expansion of the mallard (Anas platyrhynchos). Introgressive hybridization has been proposed as a principal cause of this decline. We studied a sympatric population of black ducks and mallards to determine the relative contribution of forced copulation and mixed pairs to hybrid production and test the common belief that mallards are more aggressive than black ducks. Mixed pairs (14% of all pairs), not interspecific forced copulation, likely accounted for the 2% hybridization rate on the study area. Sexual and hostile aggression was greater among mallards than black ducks prior to the establishment of territories, but thereafter was similar between the two species.
Attack on gray whales (Eschrichtius robustus) in Monterey Bay, California, by killer whales (Orcinus orca) previously identified in Glacier Bay, Alaska
Authors: Goley P. Dawn , Straley Janice M.
Published: July 2008

A group of at least 17 killer whales (Orcinus orca) were observed attacking a gray whale (Eschrichtius robustus) mother and calf on 2 May 1992 in Monterey Bay, California, U.S.A. (36°47.90′N, 122°00.17′W). Small groups of killer whales took turns harassing the gray whales and prevented them from leaving the area. Three of the killer whales participating in this attack previously had been photographed on 6 August 1989 in Glacier Bay, Alaska, U.S.A. (58°41′N, 136°04′W). This linear distance nearly doubles the maximum range of movement previously reported for killer whales.
The distribution of four Chaoborus species (Diptera: Chaoboridae) along an elevation gradient in Canadian Rocky Mountain lakes
Authors: Lamontagne S. , Donald D. B. , Schindler D.W.
Published: July 2008

We tested the hypothesis that the distribution of four species of Chaoborus is limited by water temperature in Rocky Mountain lakes. Midsummer surface water temperature (MSSWT) of Rocky Mountain lakes varied between 25 and 5 °C along an elevation gradient spanning 600–2400 m above sea level. Chaoborus (subgenus Chaoborus) americanus and C. (C.) flavicans were collected in lakes with MSSWT ≥ 16 °C, generally corresponding to lakes at elevations lower than 1600 m above sea level. Chaoborus (Sayomyia) punctipennis was only collected in warm lakes (MSSWT ≥ 21 °C). Species of the subgenus Schadonophasma (C. trivittatus and possibly C. cooki) were not commonly collected, but preliminary data suggest that they may be more tolerant of low water temperatures than the other species. On a qualitative basis, the distribution of these chaoborids in the Rockies is similar to their latitudinal distribution. However, MSSWT as a valid predictor of Chaoborus species distribution with latitude remains to be tested. The gradient in lake temperature found in mountainous environments appears to be a useful gauge for obtaining information about the distribution of invertebrates relative to temperature.
Habitat use by sympatric female mallards and American black ducks breeding in a forested environment
Authors: Dwyer Chris P. , Baldassarre Guy A.
Published: July 2008

There has been much speculation regarding whether breeding mallards (Anas platyrhynchos) and American black ducks (A. rubripes) use similar habitat types in forested areas, which could lead to increased interspecific contact. To study this issue, we used radiotelemetry during 1990–1991 on sympatric female mallards and black ducks breeding in the western Adirondack Mountains of New York. Mallard and black duck pairs occupied the general area at a density of 0.7 and 0.6/km2, respectively. Black duck home ranges tended to be larger than those of mallards, although the difference was not significant. Habitat composition within the home ranges of mallards and black ducks was similar, upland forest being the dominant habitat type, followed by wetlands, disturbed areas, and active residential sites. Within home ranges, mallards and black ducks were similar in their use of four major wetland habitat types. Our data suggest that undisturbed forest and habitat use within such areas may not serve as an isolating mechanism between breeding mallards and black ducks.
Ovary development and colony founding in subarctic and temperate-zone bumblebee queens
Authors: Vogt F. Daniel , Heinrich Bernd , Dabolt Thomas O. , McBath Heather L.
Published: July 2008

Bumblebees (Bombus spp.) are social bees that must complete their colony cycle within a single season. Those in the arctic face a much shorter flowering season than more southerly species. Here we compare behavioral and physiological features between bumblebee queens founding colonies in Denali National Park, Alaska, and queens of species from New York and Vermont. Several features that allow the more northerly bees to gain a quick start in colony founding were identified. First, the Alaskan bees emerged almost immediately (within 1 or 2 days) after the first willow blossoms began to open (while the ground was still snow covered except for a few bare patches). Within 2 days after emerging from hibernation, the first queens were already nest hunting and (or) carrying pollen, and ovary masses were increasing markedly. In contrast, the temperate-zone queens showed no synchronous emergence in early spring, and although they achieved a ratio of ovary to body mass similar to that of the Alaskan queens, it took them longer to do so, and to initiate colony founding.
Wolf and bear predation on white-tailed deer fawns in northeastern Minnesota
Authors: Kunkel Kyran E. , Mech L. David
Published: July 2008

White-tailed deer (Odocoileus virginianus) fawn mortality was studied during the summers of 1989 and 1990 in northeastern Minnesota. Estimated pooled mortality rates for 21 radio-tagged fawns were 0.44 for the May–June, 0.13 for the July–October, and 0.51 for the May–October intervals. Predation accounted for all mortalities, with wolves (Canis lupus) responsible for 51% of them and black bears (Ursus americanus) for 49%. Fawns from mothers > 4 years old weighed more and survived better than fawns from young mothers, which weighed less. Of various related factors (doe age, doe mass, fawn mass, fawn birth date, and fawn blood serum urea nitrogen (SUN)), only SUN was significant between surviving and perishing fawns; fawns with low SUN survived significantly less. Fawn SUN may have been only an indirect indicator of a doe physical or behavioral factor that was more important to fawn survival.
Study of a stunted population of yellow perch (Perca flavescens) in a monospecific lake in Gatineau Park, Quebec
Authors: Ridgway Lara L. , Chapleau François
Published: July 2008

A reported case of stunting was examined in a population of yellow perch, Perca flavescens, from a monospecific lake (Lac du Printemps) in Gatineau Park, Quebec. In total, 516 specimens were sampled in early October 1992. Females grew significantly faster than males, and also attained a greater length and age (241 mm, 10 years) than males (172 mm, 7 years). Compared with other populations in Quebec, the growth rate of this population was well below average; age-classes converged towards a similar size at earlier ages; the maximum age attained by males was less than average for the species, and males and females reached sexual maturity at an earlier age (0+ and 1+, respectively). These results are consistent with those found in stunted populations. Males aged 0+ had an average gonadosomatic index of 9.3%, which is one of the highest ever reported for this species. The index decreased gradually with age. Fish were absent from the stomach contents of 300 specimens examined. Owing to their large size, young-of-the-year yellow perch were not preyed upon by older perch at that time of year. The lack of availability of fish prey may contribute to the stunted state of this population. Other contributing factors are intraspecific competition and the absence of top predators in the population. A comparison of the population in 1981 and 1992 indicated that it has been stunted for at least a decade.
Differences in foraging behaviour between virgin and mated aphid parasitoids (Hymenoptera: Aphidiidae)
Authors: Michaud J. P.
Published: July 2008

The influence of mating status on foraging behaviour was examined in the parasitoid wasps Aphidius smithi Sharma &Subba Rao, Ephedrus californicus Baker, Monoctonus paulensis (Ashmead), Praon pequodorum Viereck, and Lysiphlebus testaceipes Cresson (Hymenoptera: Aphidiidae). Virgin females of A. smithi, M. paulensis, and P. pequodorum abandoned bean shoots infested with pea aphid, Acyrthosiphum pisum (Harris), earlier than did their mated counterparts. Virgin females of all species except L. testaceipes (host Aphis fabae Scop.) attacked fewer aphids within a patch than did mated females, and parasitized fewer hosts in a 2-h period. Females therefore tend to produce a smaller brood within a patch when unable to fertilize their eggs and produce daughters. Mated females of A. smithi and M. paulensis superparasitized more aphids than did unmated females of these species. Females of all species mated successfully and produced daughters after ovipositing as virgins. The possible fitness consequences of distinct virgin oviposition tactics are discussed.
Differentiation in juvenile growth and bimodality patterns between northern and southern populations of Atlantic salmon (Salmo salar L.)
Authors: Nicieza Alfredo G. , Reyes-Gavilán Felipe G. , Braña Florentino
Published: July 2008

Juvenile Atlantic salmon, Salmo salar, from two contrasting populations that had been reared under identical conditions differed in freshwater growth rates and the development of bimodality in length–frequency distributions. Segregation by size started at least a month earlier in the northern (River Shin, northern Scotland) than in the southern population (River Narcea, northern Spain). Northern fish initially grew faster and entered the upper modal group at a larger size (about 100 mm) than did southern fish (about 90 mm). However, the percentage of fish in the upper modal group was greater for the southern population and they grew fastest over winter and during the spring leading up to smolting, and were larger at the smolt stage. By late winter, the individual growth rates of upper modal fish were inversely correlated with their body length in December. These results suggest the existence of genetic differences between populations in the expression of growth bimodality in juvenile Atlantic salmon. This may indicate that size and growth rate thresholds determining the developmental pathway associated with age at smolt metamorphosis may vary between populations as a function of both smolt size and expected growth opportunity during winter and spring.
Impact de la maladie des points noirs sur la biologie du complexe Phoxinus (Cyprinidae) du lac Fortune, Québec
Authors: Paradis Anne Reine , Chapleau François
Published: July 2008

The purpose of this study was to quantify the effects of the black spot disease on growth, health, and fecundity of the fish and to define predictive parameters related to the infestation. Cyprinids belonging to the Phoxinus complex (P. eos, P. eos × P. neogaeus) of Lake Fortune (Gatineau Park, Québec, Canada) were sampled periodically between June and September 1992. The highest intensity of infestation was encountered in September (0–216 black spots; [Formula: see text], SD = 26.0). Our results indicate that: (i) the condition index of the Phoxinus complex and the gonadosomatic index in females are not affected by the level of infestation; (ii) age is a better predictive parameter of the number of black spots than total length; (iii) fins are significantly more infested than the body; and (iv) infestation occurs mainly between June and September. Our results suggest that the black spot disease does not influence the biology of fish belonging to the Phoxinus complex, even in instances of severe infestation.
Which characteristics might selection favour as cues of female choice of mate in Red-winged Blackbirds?
Authors: Milks Maynard L. , Picman Jaroslav
Published: July 2008

In this study, we investigated potential cues determining choice of mate by female Red-winged Blackbirds (Agelaius phoeniceus) by examining male and nest-site characteristics that (i) affect the reproductive success of females, (ii) can be assessed by females prior to mating, and (iii) vary among potential mates, in 1983–1985. The 17 characteristics considered reflected the accessibility of redwing nests to mammalian predators and to Marsh Wrens (Cistothorus palustris), the importance of cooperation between female redwings in nest defense, and the paternal quality (feeding and defense of nestlings), genetic quality, physical condition, and size of redwing males. Only 4 characteristics, distance to nearest wren nest, distance to nearest simultaneously active conspecific nest, height of vegetation supporting the nest, and nest defense effort of males, met all of the above criteria in at least 1 year. Of these, proximity to wren nests appeared to satisfy the requirements most consistently in time and space, and thus might be the most likely to affect female redwing choice of mate. However, experimental manipulations are needed to ascertain whether any of these characteristics are cues of female mate choice in Red-winged Blackbirds.
The effects of temperature and feeding regime on hermaphroditism and gametogenesis of Nephelopsis obscura, a freshwater predatory leech
Authors: Biernacka B. , Davies Ronald W.
Published: July 2008

The effects of temperature (15 and 20 °C) and food ration (feeding 33, 23, or 13 per week (ad libitum)) on hermaphroditism and gametogenesis of Nephelopsis obscura were investigated in the laboratory. Animals fed 33 and 23 a week reached an asymptotic biomass and reproductive maturity at approximately the same time (41–43 weeks) at both 15 and 20 °C. However, none of the leeches fed 13 a week attained the final stages of reproductive maturity, even though they reached an asymptotic biomass. Regardless of temperature or food ration, testisacs were initiated when N. obscura reached 62–87 mg and ovisac initiation always occurred 3 weeks after the first occurrence of the testisacs. In contrast to the field, where N. obscura is protandrous, in the laboratory N. obscura is protogynous because of the increase from 2–5 to 15–22 weeks between stages 4 and 5 of spermatogenesis.
Plasma levels of lactate, potassium, glucose, cortisol, growth hormone and triiodo-L-thyronine in rainbow trout (Oncorhynchus mykiss) during exercise at various levels for 24 h
Authors: Nielsen Michael E. , Boesgaard Lars , Sweeting Ruston M. , McKeown Brian A. , Rosenkilde Per
Published: July 2008

To examine the initial hormonal and metabolic changes in exercising fish, rainbow trout (Oncorhynchus mykiss) were subjected to moderate (1.5 body lengths/s) or low (0.5 body lengths/s) water velocities for 24 h and compared with unexercised controls. Blood sampling occurred immediately before (0 h) and at 1, 2, 4, 8, and 24 h after the onset of exercise for determination of plasma concentrations of lactate, potassium, glucose, cortisol, growth hormone, and triiodo-L-thyronine (T3). There was no effect of either exercise or time on plasma lactate levels in any of the three groups, indicating that neither exercise regime induced anaerobic conditions. Within the first 2 h of exercise, plasma, K+, glucose, cortisol, and growth hormone levels were all significantly (P < 0.05) elevated over controls in the moderate-exercise group. By 4 h, none of these parameters were significantly different from controls except plasma K+ levels, which remained significantly higher throughout the experiment. There were no differences between 0 and 24 h of exercise in any parameters of any of the groups, again with the exception of plasma K+ levels in the moderate-exercise fish, which were significantly higher at 24 h. It is concluded that the effects of the onset of exercise resemble those described for acute stress in fish. Furthermore, short-term (24 h) exercise at moderate levels (1.5 body lengths/s) resulted in continuously elevated plasma K+ levels, but did not seem to cause similar increases in the other parameters.
Effects of lampricides on the gill ultrastructure of larval sea lampreys and rainbow trout fry
Authors: Mallatt Jon , McCall R. Dale , Bailey J. Franklin , Seelye James
Published: July 2008

Larval lampreys (Petromyzon marinus) and rainbow trout fry (Oncorhynchus mykiss) were exposed to toxic solutions of the lampricidal chemicals TFM (3-trifluormethyl-4-nitrophenol) and Bayer 73 (5,2′-dichloro-4′-nitrosalicylanilide). Both species were exposed to their 9-h LC100 for 9 h or until they were near death. The respiratory lamellae of the gills were then studied with transmission electron microscopy. In lampreys, damage was confined to presumed ion-uptake cells. Both lampricides produced similar changes in these cells: cell rounding, enlargement of mitochondrial profiles, vacuolization of the cytoplasm, and widening of the intercellular spaces. Bayer 73 caused a greater incidence of necrosis of ion-uptake cells than did TFM. Exposure to lethal TFM/Bayer-73 mixtures (containing 0.4–1.6% Bayer 73) affected lamprey gill lamellae in the same way as did Bayer 73. Unlike lamprey gills, trout gills were entirely unaltered by levels of the lampricides lethal to trout. These findings suggest that (i) disruption of ion-regulating cells contributes to the mortality of lampreys exposed to lampricides and to the high susceptibility of lampreys to TFM; (ii) the mechanisms of cytotoxicity of TFM and Bayer 73 are similar.