bluuebunny/crossref_metadata_2025 huggingface dataset:
Male quality and song repertoires in western meadowlarks (Sturnella neglecta)
Authors: Horn Andrew G. , Dickinson Thomas E. , Falls J. Bruce
Published: July 2008

The relationship between song repertoire size and measures of male quality and reproductive success was examined in a Manitoba population of western meadowlarks (Sturnella neglecta). Repertoire size correlated positively with the singer's wing length but not with mass or territory size. Males with larger repertoires tended to pair earlier and males with higher pairing success had larger repertoires. Repertoire size correlated positively with fledging success independently of pairing success. As suggested for other species, repertoire size might serve as a signal to females of male quality. We suggest mechanisms by which this signalling system is maintained.
Morphological variation in the harbour porpoise (Phocoena phocoena)
Authors: Curren Krishna , Bose Neil , Lien Jon
Published: July 2008

Average values of morphological parameters for mature harbour porpoise (Phocoena phocoena) are presented. Variation in these parameters with body length was examined for a sample of 35 porpoise. Several parameters including fineness ratio, fluke aspect ratio, and the ratios of fluke area:body surface area and (body surface area)1/2:(body volume)1/3 were found to vary with body length. Fluke aspect ratio was inversely proportional to fluke sweep angle. The finding that many morphological parameters vary with length for harbour porpoise indicates the dependence of these parameters on age; this may also be true for other cetacean species.
Daytime and nighttime activity at a breeding colony of Great Blue Herons in a nontidal environment
Authors: McNeil Raymond , Benoît Rejean , Desgranges Jean-Luc
Published: July 2008

It is generally admitted that in coastal areas, herons of the genus Ardea adjust their foraging time according to the tidal cycle. However, to what extent do tides control the herons' daily rhythm of activity? To answer this question, we present the day and night activity patterns of Great Blue Herons (Ardea herodias) arriving to feed their young at a heronry located in a nontidal environment in southern Quebec. Herons were about half as active at night as during the day. Therefore, although significantly less than diurnal activity, nocturnal activity was not negligible, and consequently the tide cycle is not the only factor controlling the daily rhythm of the herons' activity. Those breeding pairs that were most active during the day were no more or less active at night. Diurnal activity was more closely correlated with the number of young that fledged than was nocturnal activity. Thus, night activity was not necessarily important for the survival of young herons, but it could be explained by other factors such as the greater availability of certain prey at night.
How do population density and food supply influence social behaviour in the snowshoe hare (Lepus americanus)?
Authors: Ferron Jean
Published: July 2008

The influence of population density and food on the social behaviour of the snowshoe hare (Lepus americanus) was studied in an outdoor enclosure. The year was divided into two periods: the nonbreeding season (October to March) and the breeding season (April to August). During each period, data on social interactions were recorded for groups of 4, 6, 8, and 10 animals, with three different sets of animals for each group size. Agonistic behaviour characterized social encounters between hares year-round. During the nonbreeding season, there was a significant correlation between agonistic behaviour and group size for females only. During the breeding season, the rate of interaction was lower and agonistic behaviour was significantly and negatively correlated with group size for males only. Two-way ANOVA of total agonistic behaviour revealed that group size and sex interacted significantly only during the nonbreeding season. The different categories of agonistic behaviour (aggression, threat, and taking the place of another animal) were also analysed separately. The distribution of aggression within each of the experimental groups indicated that the two top-ranking animals were generally males and that they initiated most of the aggressive encounters. Another experiment with restricted food availability was conducted to study the impact of limited resources on agonistic behaviour. Hares were significantly more aggressive when food was restricted than when food was available ad libitum. It thus appears that food availability has a stronger influence on social behaviour than does hare density.
Reproductive investment by green turtles nesting on Ascension Island
Authors: Hays Graeme C. , Adams Colin R. , Speakman John R.
Published: July 2008

Clutch sizes and egg sizes were measured for green turtles (Chelonia mydas) nesting on Ascension Island in the South Atlantic (7°57′S, 14 °22′W) in 1992. The mean number of eggs per clutch was 127.5 (SD = 22.9; n = 46 clutches). The number of eggs per clutch increased in larger turtles and declined as the nesting season progressed. Mean egg size was 45.5 mm (SD = 1.45 mm; n = 47 clutches). Three turtles laid significantly smaller eggs than the rest of the sample. When these three clutches were removed from the analysis, mean egg size increased in larger turtles. When the effect of female body size was removed there was no relationship between the number and size of the eggs in a clutch. The depth from the top to the bottom of the egg chamber, the depth from the top of the egg chamber to the topmost egg, and the depth of the body pit were all independent of adult size. Egg size varied systematically within clutches, the largest eggs being laid first and the smallest eggs last. This intraclutch variation in egg size had important consequences for the calculated gradient of the relationship between egg size and adult size.
Temporal changes in the structure of the male nuptial signal in the brook stickleback, Culaea inconstans (Kirtland)
Authors: McLennan Deborah A.
Published: July 2008

Within the Gasterosteidae, only members of the clade Culaea + Pungitius + Gasterosteus contain nuptially coloured males. Of these males, the nuptial signal has been subjected to detailed experimental examination in one species, the three-spined stickleback, Gasterosteus aculeatus. Since most components of the signal did not originate in G. aculeatus, descriptions of signal structure and variability for other members of the Gasterosteidae are a critical prerequisite to discussions of the processes underlying the evolution of male nuptial colouration in these fish. In this paper I investigated the changes in the male nuptial signal for another member of the clade, the brook stickleback, Culaea inconstans. The results of this investigation revealed that as in G. aculeatus, the signal is a complex mosaic, in this case representing the interaction between changes in the intensity of black pigmentation in the ventral – lateral body surface, the dorsal – lateral body surface, the eye bar, the fins, and the spines. These variables interacted to produce four distinct male colour mosaics corresponding to the stage a male had reached in the breeding cycle and the sex of an intruding conspecific.
External morphology of Dall's porpoise (Phocoenoides dalli): growth and sexual dimorphism
Authors: Amano Masao , Miyazaki Nobuyuki
Published: July 2008

We studied development and sexual dimorphism in external measurements of Dall's porpoises (Phocoenoides dalli) from the northwestern North Pacific. Relative rates of increase in the measurements of the head and flipper decrease postnatally, while those of the flukes, dorsal fin, and girths in the posterior part of the body do not. Growth patterns of the flukes and increase in girth at the anus are different from those in other small odontocetes. This is considered to be related to the fast swimming and presumed deep diving behavior of Dall's porpoise. Growth rates of appendages decrease with time after birth, as in other cetaceans. Secondary sexual features of males appear in the dorsal fin, flukes, and girth at the anus; the flukes show more distinct sexual dimorphism than the dorsal fin.
Effects of 17β-estradiol on pituitary and testicular function in male goldfish
Authors: Trudeau V. L. , Wade M. G. , Kraak G. Van Der , Peter R. E
Published: July 2008

The potential involvement of 17β-estradiol in the regulation of pituitary and testicular function was investigated in male goldfish at various times during the seasonal reproductive cycle. Serum levels of testosterone, 11-ketotestosterone, and 17β-estradiol were 10, 16, and 4 times higher in mature males (tubercles on the pectoral fins and milt production; March) than in sexually regressed males (no tubercles or milt production; July). Intraperitoneal injection of [D-Arg6,Trp7,Leu8,Pro9-NEt]gonadotropin releasing hormone (sGnRH-A, 0.01 μg/g) elevated serum gonadotropin II levels within 6 h, and there was a concomitant increase in testosterone but not 17β-estradiol levels in sexually regressing male goldfish (October). Males in the early stage of testicular recrudescence (November) had increased serum levels of gonadotropin II and testosterone in response to [D-Ala6,Pro9-NEt]GnRH (LHRH-A, 0.1 μg/g) or the dopamine antagonist domperidone (5 μg/g). Males implanted intraperitoneally for 10 days with solid Silastic pellet implants containing 17β-estradiol (100 μg/g) had lower basal testosterone levels and a reduced testosterone response to both LHRH-A and domperidone. The serum gonadotropin II response to LHRH-A but not domperidone was enhanced by 17β-estradiol. Male goldfish in mid-recrudescence receiving 17β-estradiol implants for 4 days had lower basal testosterone and 11-ketotestosterone levels than controls. Combined treatment with sGnRH-A (0.1 μg/g) and domperidone (10 μg/g) elevated serum testosterone and 11-ketotestosterone levels at 24 h; the serum androgen response was reduced in 17β-estradiol-implanted fish. These studies support the concept that 17β-estradiol plays a role in the regulation of reproduction in male goldfish by enhancing pituitary gonadotropin II release and by reducing testicular androgen production.
Seasonal patterns in trap catches of the crayfish Cambarus bartoni and Orconectes virilis in six south-central Ontario lakes
Authors: Somers Keith M. , Green Roger H.
Published: July 2008

Crayfish were trapped in six south-central Ontario lakes to examine seasonal changes in estimates of relative abundance. Baited-trap catches of Cambarus bartoni and Orconectes virilis correlated with changes in water temperature. Cambarid catches increased in the spring until a midsummer maximum, but dropped suddenly as the water temperature began to fall in August. Ovigerous (i.e., egg-bearing) females and recently moulted males were captured by SCUBA divers in August. Trap catches increased, once breeding and moulting periods concluded, and subsequently decreased as water temperatures continued to drop in the autumn. In contrast, catches of male O. virilis increased in the spring and remained relatively constant throughout the summer until water temperatures fell in September. Catches of female O. virilis peaked somewhat later in the summer and then gradually declined in the early fall. Although the two species and the two sexes differed in the length of the midsummer sampling period when trap catches were relatively constant, similar seasonal trends among lakes suggest that midsummer trap catches can be used to estimate crayfish relative abundance. Other factors, such as the presence of smallmouth bass (Micropterus dolomieui), lake physical and chemical characteristics, and the number of co-occurring crayfish species also correlated with trap catches. Both the presence of bass and the number of co-occurring species of crayfish probably affect crayfish behaviour and activity, thereby reducing catches in baited traps, but not necessarily affecting actual population abundance. Comparisons of relative abundance based on catches from baited traps must control for these seasonal behavioural, and environmental factors.
Distribution, density, and growth of young-of-the-year fishes in Mitchell Bay, Lake St. Clair
Authors: Leslie J. K. , Timmins C. A.
Published: July 2008

Thirty-eight taxa of young-of-the-year fishes were collected with a beach seine and plankton nets in Mitchell Bay, a shallow, densely vegetated embayment on Lake St. Clair, from April to October, 1983, 1984, and 1990. The ecosystem of the bay and adjacent land has been altered by agricultural, industrial, and recreational development for more than a century. Although taxa were numerous, most species were rare or uncommon in collections. The assemblage of larval fish consisted primarily of brook silverside (Labidesthes sicculus), pumpkinseed (Lepomis gibbosus), spottail shiner (Notropis hudsonius), emerald shiner (Notropis atherinoides), alewife (Alosa pseudoharengus), and gizzard shad (Dorosoma cepedianum). Many species were distributed in or near submerged macrophytes at the shore. The species most abundant were pumpkinseed, which reached peak density (11 931 young of the year/100 m3) in late June 1990, and brook silverside (1363 young of the year/100 m3) in late June 1984.
Effets d'un élevage en isolement sur le développement gonadotrope, la production d'hydrocarbures cuticulaires et le comportement sexuel de Calliphora vomitoria (Diptères, Calliphoridae)
Authors: Benziane Taoufiq , Campan Mireille
Published: July 2008

Isolated rearing (during the first gonadotropic cycle) was found to modify physiological variables (gonadotropic development, cuticular hydrocarbon production) as well as behavioral modalities of the courtship of male and female Calliphora vomitoria. In males, slower development and a decrease in the volume of the testes and the annex glands were noticed; in females, there was only a reduction in the volume of the terminal follicle without modification of the rate of growth. In contrast, cuticular hydrocarbon production was more disturbed in the female than in the male. Isolated rearing of males did not change either the number or the relative proportions and concentrations of cuticular hydrocarbons. In females, isolation was accompanied by a slight increase in both the relative proportions of cuticular hydrocarbons, namely monomethyalkanes, dimethylalkanes, and alkenes, and the concentrations of all hydrocarbons. Finally, isolated rearing was found to modify the sexual behavior of both partners. Isolated males showed later and scarcer sexual behavior than grouped males. They courted females later and more briefly, with lower frequencies and shorter durations of each stage of courtship; therefore, courtship was reduced with many interruptions. Isolated females appeared more permissive, with lower frequencies and durations of the stages of courtship, and shorter courtship. These differences were emphasized when both partners were reared in isolation. The lack of exchanges during imaginal development led, owing to lack of exercise and (or) nervous maturation, to sex-specific alterations: decreased gonadotropic development in males, modified cuticular hydrocarbon production in females, and reduced sexual behavior in both sexes.
Dietary fats and torpor patterns in hibernating ground squirrels
Authors: Geiser Fritz , Kenagy G. J.
Published: July 2008

The effect of a sunflower oil diet (rodent chow with 10% addition by weight of sunflower seed oil, rich in linoleic acid), a sheep fat diet (rodent chow with 10% addition by weight of sheep fat, rich in saturated fatty acids and oleic acid), and a control diet (rodent chow without added fat or oil) on the pattern of torpor was investigated in the ground squirrel Spermophilus saturatus, a relatively large (250 g) hibernator. Torpid S. saturatus on the sunflower oil diet showed a lower minimum body temperature (2.1 vs. 3.5 °C), a lower metabolic rate (0.029 vs. 0.043 mL O2/g∙h)), and longer bouts of torpor (252 vs. 193 h at an air temperature of − 1.0 °C) than animals on the sheep fat diet. These physiological variables showed intermediate values in controls. It appears, therefore, that the composition of dietary fatty acids, rather than the fat content of the diet, affected torpor patterns. It is likely that the observed physiological differences may be explained by diet-induced compositional differences in body lipid composition.
Effects of food resource distribution on the social system of Gunnison's prairie dog (Cynomys gunnisoni)
Authors: Travis Steven E. , Slobodchikoff C. N.
Published: July 2008

We tested the predictions of Slobodchikoff s habitat variability – mating system model using the social system of Gunnison's prairie dog (Cynomys gunnisoni). The model predicts that when resources are abundant and patchily distributed, social groups will include several females, while scarce, uniformly distributed resources will lead to smaller groups with single females. Gunnison's prairie dogs form family groups consisting of a single adult male and female(s), and their young of the year, which occupy fixed spatial territories within a colonial framework. Resource abundances and distributions were characterized and compared at two colonies in northern Arizona. Resource abundance did not vary between colonies, while two separate measures showed resource distribution to be significantly more patchy at one colony than at the other. As predicted, there were significantly more territories with multiple females at the patchy colony, while single-female territories predominated at the uniform colony. While the differences in resource abundance between colonies were not significant from a statistical standpoint, sizable differences were observed, with the direction of the difference opposite to that predicted by the model.
Intraspecific variation in sibling species of Simulium venustum and Simulium verecundum complexes (Diptera: Simuliidae) revealed by the sequence of the mitochondrial 16S rRNAgene
Authors: Xiong Bai , Kocher Thomas D.
Published: July 2008

A portion of the mitochondrial large ribosomal RNA gene was amplified and sequenced (460 base pairs) for 10 individuals of each of nine samples of black flies representing three sibling species of the Simulium venustum complex (CC, CC3, and AC(gB)) and two sibling species of the Simulium verecundum complex (ACD = Simulium rostratum and AA). Mitochondrial DNA haplotype heterogeneity was observed in all but the sample of S. verecundum AA from New Hampshire. The sample of S. venustum CC3 had a significantly larger number of haplotypes than other samples. A predominant haplotype was found in most samples except S. venustum CC3 and S. venustum CC from New Hampshire (nine haplotypes in the sample of S. venustum CC3 and two haplotypes with equal frequency in the sample of S. venustum CC from New Hampshire). The predominant haplotype was the same among the three samples of S. verecundum AA. Samples of S. venustum CC also shared haplotypes, but the predominant haplotype was different in each sample. Despite intraspecific variation, haplotypes are usually clustered on a conspecific basis.
Transmission of Myxobolus arcticus Pugachev and Khokhlov, 1979, a myxosporean parasite of Pacific salmon, via a triactinomyxon from the aquatic oligochaete Stylodrilus heringianus (Lumbriculidae)
Authors: Kent M. L. , Whitaker D. J. , Margolis L.
Published: July 2008

Laboratory transmission studies were conducted on Myxobolus arcticus, a myxosporean that infects the brain of Pacific salmon (Oncorhynchus spp.). Attempts at transmission from fish to fish with spores of M. arcticus from sockeye salmon (Oncorhynchus nerka), including experiments with spores aged for up to 9 months in sterilized mud, were unsuccessful. Transmission was achieved when hatchery-reared (in well water) sockeye salmon fry were exposed to the oligochaete Stylodrilus heringianus collected from a lake where M. arcticus infections are common in this fish. All experimental fish exhibited the infection when examined 3 –4 months after exposure. Of 23 sockeye salmon fry exposed to triactinomyxon spores collected from naturally infected S. heringianus, 21 were found to be infected with M. arcticus spores when examined after 3 months. Thus, the life cycle of M. arcticus involves transformation into a triactinomyxon stage in S. heringianus. Alternate development of myxosporeans in aquatic oligochaetes has been established or implicated for nine other species of myxosporeans belonging to three families, but this is the first report of alternate development in a lumbriculid worm.
The immature stages and biology of the unusual North American arctic caddisfly Sphagnophylax meiops, with consideration of the phyletic relationships of the genus (Trichoptera: Limnephilidae)
Authors: Winchester N. N. , Wiggins G. B. , Ring R. A.
Published: July 2008

Larvae and pupae of Sphagnophylax meiops Wiggins and Winchester, previously unknown, are identified from a transient arctic tundra pool near Tuktoyaktuk, Northwest Territories, Canada (69 °29′N, 132 °35′W). Surface water persisted in the basin of the pool, where larvae were evident for about 2 weeks in June, then receded into water-saturated organic materials above the permafrost, where larvae completed feeding, growth, and metamorphosis. The species has a univoltine life cycle, and adults emerge over a 5-week period from late June to the end of July. Adults are brachypterous and evidently flightless. Assignment of the genus Sphagnophylax to a tribe within the subfamily Limnephilinae is unusually complex. Long bristles on the forewings are synapomorphic with the Chaetopterygini, but female genitalic structure suggests affinity with the Limnephilini. The genitalic structure of males indicates no clear relationship with the Limnephilini, but similar tendencies in some characters suggest distant affinity with the genus Philarctus, which is itself somewhat aberrant within the Limnephilini. The significance of these tendencies cannot be fully assessed until phylogenetic analysis of the subfamily Limnephilinae has been carried out. The larval gill structure consisting of multiple filaments in Sphagnophylax is shared with all of the Limnephilini, and is probably an apomorphic character. The genus Sphagnophylax is assigned to the tribe Limnephilini, and is interpreted as a relict group.
Growth and survival of newly emerged and juvenile coho salmon (Oncorhynchus kisutch) reared at different salinities
Authors: Murray C. B. , Beacham T. D. , Barner L. W.
Published: July 2008

Newly emerged coho salmon (Oncorhynchus kisutch) from 40 families of a coastal-spawning population were reared in fresh water and seawater for 144 d after ponding. Growth and survival were, on average, higher in fresh water than in seawater, but juveniles from some families had higher or equivalent survival in seawater compared with fresh water. Heritability (sire variance component) of survival and length ranged between 0.30 and 0.35. The transfer of juveniles from fresh water to 15‰ seawater after 70 d of rearing in fresh water had little effect on their subsequent growth and survival. In a second experiment, newly emerged fry from a coastal- and an interior-spawning population had the same survival in fresh water, but survival was higher for the coastal population than for the interior population in 15 or 25‰ seawater. Rearing environment had no effect on survival for the coastal population, but as rearing salinities increased, survival for the interior population decreased. Within a population, length, weight, and instantaneous growth rates for length and weight decreased with increased rearing salinity. The growth and survival of some juveniles in a saline environment were comparable to those observed for juveniles reared in fresh water, indicating that the marine environment provides a suitable rearing environment for some coho salmon.
Preliminary observations on blood flow in the coronary arteries of two school sharks (Galeorhinus australis)
Authors: Davie Peter S. , Franklin Craig E.
Published: July 2008

Coronary arterial blood flow and pressure, intraventricular blood pressure, and ventral aortic blood velocity were measured in two anaesthetized school sharks (Galeorhinus australis) in order to examine the phasic relationships between these flows and pressures. Maximum instantaneous flow recorded in the ventral coronary artery was 0.37 mL∙min−1∙kg−1 body mass (estimated 0.63 mL∙min−1∙g−1 ventricular mass). The average mean coronary blood flow was estimated as 0.28 mL∙min−1∙g−1 ventricular mass during periods of high coronary blood flow. On average, 86% of coronary flow occurred during diastole. Coronary arterial flow began during the last quarter of ventricular systole. Coronary blood flow peaked when intraventricular pressure fell to just below zero immediately after ventricular systole. Coronary blood flow fell slightly as diastole continued and reflected the small fall in coronary arterial pressure. Coronary flow reversed briefly during isovolumic ventricular contraction. Increases in the proportion of the cardiac cycle occupied by ventricular diastole, which occur during hypoxic bradycardia, have the potential to more than double coronary blood flow provided coronary arterial pressure is maintained.
Internal anatomy of female Paramphiascella fulvofasciata (Copepoda, Harpacticoida)
Authors: Dahms H.-U.
Published: July 2008

The gross internal anatomy of females of a harpacticoid copepod, Paramphiascella fulvofasciata Rosenfield and Coull, 1974, was studied using light and transmission electron microscopy. The central nervous system consists of a protocerebrum, connectives, a subesophageal ganglion, and a ventral nerve chain bifurcating twice in the abdomen. The longitudinal musculature of the trunk consists of ventral and dorsal bilaterally symmetrical bundles of muscle fibres. The protractors and dilatators of a swimming leg are attached to tendons of the exoskeleton and the protopodite. The female genital system comprises an unpaired ovary in the frontal portion of the cephalothorax and a pair of oviducts extending towards a chitinized antrum, which lead to the genital apertures or vulvae. The formation of paired egg sacs is discussed. The alimentary tract consists of an esophagus, midgut, and hind gut. A midgut diverticulum is absent. The anus opens between and dorsal to the caudal rami and is overlapped by an anal operculum. Food uptake and fecal pellet formation are discussed.
Habitat selection by common eiders in winter and its interaction with flock size
Authors: Guillemette Magella , Himmelman John H. , Barette Cyrille , Reed Austin
Published: July 2008

We studied habitat selection in relation to prey density and water depth in the common eider, Somateria mollissima L., wintering in the Gulf of St. Lawrence, eastern Canada. In this region, eiders are confronted with low temperatures, ice cover, and reduced day length. We predicted that they should select feeding habitats characterized by high prey density and shallow water to minimize the time and energy spent while diving. About 1000 flocks were localized by triangulation on our study site (20.5 km2). We inferred the diving depth and the habitat being used from the position of eiders on bathymetric and community maps. The highest density of prey occurred in shallow water reefs where there were patches of blue mussels, Mytilus edulis L., and green sea urchins, Strongylocentrotus droebachienensis (Müller). Despite the fact that eiders can dive to depths as great as 42 m to feed, they strongly aggregate in shallow water, and their distribution closely coincides with the highest density of prey. The degree of selection for the reef habitat varies with seasonal variations in the size of flocks and in the total number of eiders present. Although flocking as an antipredator behaviour cannot be rejected, we interpret the high degree of flocking by eiders in our study area as a strategy to facilitate feeding in winter.
Nest-site preference in male fathead minnows, Pimephales promelas
Authors: DeWitt Thomas J.
Published: July 2008

Nest-site preference in fish is not often studied, and yet it should yield insight into their successful reproduction. I placed three sizes of artificial nest structures at three depths and on two sides of a Michigan pond to investigate nest usage patterns by male fathead minnows. Of 93 artificial nest structures available, 18 were used as nests. Northern nest sites were used more than southern sites, and structures of 100 and 200 cm2 were used more than those of 50 cm2. There was no differential use of structures between depths of 0.25 and 1 m. Other site preferences and alternative male mating strategies were also suggested.
The influence of nest sharing on the expression of daily torpor in the white-footed mouse
Authors: Vogt F. Daniel , Kakooza Peter
Published: July 2008

During winter the white-footed mouse, Peromyscus leucopus noveboracensis, often becomes torpid when huddled with other mice. While some mice become torpid on a regular basis, others only infrequently, or never, become torpid. Mice acclimated to cold and to short daylength were monitored by direct observation and with radiotelemetry equipment to determine the influence of sharing a nest on the occurrence and body temperature characteristics of daily torpor. Similar numbers of individually caged mice and mice caged in groups of three became torpid at least once. The frequency of torpor (how often mice become torpid) was also similar for solitary and huddled animals. When mice known to enter torpor were caged in groups of three, usually huddlemates all became torpid (54%) or all remained euthermic (32%) on any particular day. Observations of "mixed" huddles (14%) of torpid and euthermic mice were less common, suggesting that physical disturbance by euthermic mice inhibits the expression of torpor in huddlemates. The individual body temperature profiles of torpid huddlemates were similar and resemble the characteristic profile reported for solitary mice. Moreover, perturbation in body temperature during torpor in one mouse often coincided with a similar adjustment in a torpid huddlemate.
A new species of Theromyzon (Rhynchobdellida: Glossiphoniidae), with a review of the genus in North America
Authors: Oosthuize J. H. , Davies Ronald W.
Published: July 2008

A new species of duck leech, Theromyzon bifarium, is described which, like T. rude and T. maculosum, has the gonopores separated by two annuli. Theromyzon bifarium is distinguished by the presence of a cylindrical male atrium, paired dorsolateral male ducts which enter the atrium separately, and a posteriorly directed loop formed by the long common oviduct. The nominal species of Theromyzon in North America are reviewed and the diagnostic differences amongst the five species (T. bifarium, T. maculosum, T. rude, T. tessulatum, T. trizonare) are presented.
Antlerless females among reindeer and caribou
Authors: Reimers E.
Published: July 2008

The frequency of occurrence of female reindeer and caribou (Rangifer tarandus) without antlers was recorded in the field in southern Norway, Svalbard, Iceland, eastern and western Greenland, and Newfoundland. Additional data were retrieved from the literature. The study showed that antlerless Rangifer females occur throughout their habitat, though they are generally more common among woodland populations than among tundra or alpine populations. Antlerless males are extremely rare. Within subspecies, the frequency of occurrence of antlerless females varies with geographical location: 5 – 47% in Svalbard reindeer, 21 – 79% in western Greenland caribou, and 12 – 92% in Newfoundland woodland caribou. Within the same population the frequency has changed over time, as at Snøhetta and Hardangervidda in southern Norway and possibly also in Newfoundland (the Interior herd). Among tundra reindeer in southern Norway there appears to be a relationship between habitat quality, body size or physical condition, and antler status. Antlerless females are few or absent in populations in prime physical condition and common in populations with animals in poor condition.
Environmental cues of estrus in the North American red squirrel (Tamiasciurus hudsonicus Bangs)
Authors: Becker C. Dustin
Published: July 2008

During three breeding seasons, variation in the timing of estrus was monitored in wild red squirrels (Tamiasciurus hudsonicus) in a jack pine forest in central Alberta. The proximate environmental factors that affect the timing of the onset of the breeding season in female squirrels, and variation in dates of estrus, were studied in parallel laboratory and field manipulations. Wild squirrels given ad libitum sunflower seed experienced a positive energy balance (weight gains) earlier in the season than did females on a normal diet. Seed addition advanced dates of estrus by an average of 3 weeks. Three potential cuing mechanisms for the seasonal onset of estrus were proposed and tested: onset of estrus is cued by (i) a simple response to net energy gain, (ii) an interaction between an endogenous circannual rhythm and net energy gain, or (iii) an interaction between annual changes in photoperiod and net energy gain in the absence of a circannual rhythm. Our results refute the first and third mechanisms, and support the idea that red squirrels have a circannual reproductive cycle entrained by photoperiod. Net energy gain interacts with this annual cycle to fine tune the time of ovulation. In laboratory experiments, female squirrels exposed to increasing day length experienced estrus within the normal season. Squirrels kept in constant short-day conditions (< 12 h), had delayed estrus cycles. Short-day conditions did not prevent the annual cycle of reproduction, indicating that an endogenous rhythm exists and is entrained by increasing day length. Comparisons with hibernating squirrels are discussed.
Paedomorphosis in the family Phytoseiidae (Acari: Gamasina)
Authors: Chant D. A.
Published: July 2008

The Phytoseiidae are characterized by idiosomal hypotrichy. The process of setal suppression that caused this hypotrichy has led to paedomorphosis due to the differential suppression of setae appearing in the later developmental stages of ancestral forms; hence there is a tendency for larval setation to persist into the adult stage of modern phytoseiids, with few setae being added in the later stages of ontogeny. Because setal suppression seems to have been accompanied by reductions in development time and body size, it is suggested that paedomorphosis in this group is of the type defined as sequential progenesis.
31P magnetic resonance spectroscopy of the liver region and liver of mice infected with Mesocestoides vogae
Authors: Novak Marie , Hudspeth Claudia , Buist Richard , Blackburn Barry
Published: July 2008

In vivo 31P NMR spectra of the liver region of mice infected with Mesocestoides vogae for 24 or 133 days showed modifications in phosphorus-containing metabolite ratios when compared with those of normal mice. In acute infection (i.e., 24 days) the metabolite ratios phosphomonoesters/adenosine triphosphate (ATP), inorganic phosphate (Pi)/ATP, and phosphodiesters/ATP in the liver region significantly increased, whereas phosphocreatine (PCr)/ATP significantly decreased; PCr is a contribution from body wall overlying the liver. Most of these metabolic alterations diminished in chronically infected mice (i.e., 133 days), but the increase in the Pi/ATP ratio persisted, and the PCr/ATP ratio decreased further. Analysis of liver extracts revealed significantly higher concentrations of phosphorylethanolamine (PE), glycerolphosphorylethanolamine (GPE), and glycerolphosphorylcholine (GPC) and significantly lower concentrations of glycerol-3-phosphate, 5′-adenosine monophosphate, Pi, ATP, adenosine diphosphate (ADP), and diphosphodiesters compounds in the livers with acute infection, whereas in those with chronic infection only PE stayed elevated and Pi, ATP, and ADP concentrations decreased further. In addition, in all infected livers, two more compounds, phosphoenolpyruvate and PCr, were present in measurable amounts. The significance of these findings in terms of liver function and pathology is discussed.
Intermediate hosts as source communities
Authors: Bush Albert O. , Heard Jr. Richard W. , Overstreet Robin M.
Published: July 2008

We describe helminth communities in two sympatric species of intertidal crabs (Pachygrapsus transversus and Panopeus lacustris) that serve as intermediate hosts for helminth parasites. We suggest that a single definitive host feeding briefly on Pachygrapsus transversus may be colonized simultaneously by up to six species of microphallid trematodes and that infrapopulations can increase rapidly by a definitive host feeding on Panopeus lacustris. Therefore, we argue that consideration of colonization processes in definitive hosts may be a crucial underpinning to many community-level studies. We show that, in Florida, colonization of Cerithidea scalariformis by miracidia is markedly different from observations made on Cerithidea californica in California. Also, different populations of C. scalariformis are highly variable in the helminths they support. We conclude that community-level studies on invertebrate intermediate hosts may be easier and more informative than similar studies on definitive hosts.
Terrestrial life in isopods: evolutionary loss of gas-exchange and survival capability in water
Authors: Taylor Barbara E. , Carefoot Thomas H.
Published: July 2008

Survival and oxygen uptake in air and water were investigated in four species of terrestrial isopods, Armadillidium vulgare Latreille, 1804, Porcellio scaber Latreille, 1804, Oniscus asellus Linné, 1758, and Ligia pallasii Brandt, 1833, to compare the degree of vestigial adaptation to aquatic existence versus adaptation to terrestrial existence. Most submerged A. vulgare, P. scaber, and O. asellus died by 18 h, whether in fresh water or isosmotic seawater. Ligia pallasii lived for almost 2 d in fresh water and for at least 25 d in seawater (none died during this time). Oxygen uptake in water was 44 – 66% that in air for the three fully terrestrial species, and 160% that in air for the semiterrestrial L. pallasii. Oxygen consumption of submerged A. vulgare (representative of fully terrestrial forms) declined to 50% after 14 h and to 17% by 24 h, by which time the animals were clinically dead. In comparison, L. pallasii's aquatic oxygen consumption was maintained at normal or higher levels for at least 3 d. All species could survive several hours of immersion in fresh water, sufficient to withstand temporary rain deluge. Ligia pallasii's superior capabilities to survive and respire in seawater reflect its greater similarity to aquatic ancestors, and an evolutionary series showing progressive decline in survival and gas-exchange capability in water would be as follows: L. pallasii > O. asellus > P. scaber ≥ A. vulgare.
Dynamics of a snow shoe hare population in fragmented habitat
Authors: Keith Lloyd B. , Bloomer Sara E. M. , Willebrand Tomas
Published: July 2008

During November 1988 – December 1991 we livetrapped, radio-collared, and monitored the survival, reproduction, and movements of snowshoe hares (Lepus americanus) in highly fragmented habitat near the species' geographic limit in central Wisconsin. Our 7 study areas centered on 5- to 28-ha patches of prime habitat: dense stands of willow (Salix), alder (Alnus), and regenerating aspen (Populus) on poorly drained soils. Maximum hare densities averaged 1.6 – 0.8/ha, and were unrelated to patch size. Rapid declines to extinction occurred on 3 of the 5 smallest study areas; on another, where extinction seemed imminent, juvenile ingress restored the population. On the 2 largest areas (23 – 28 ha of prime habitat) hare populations were stationary during the first 2 years, but declined by 50 – 70% in the third as mean annual (September – August) survival of radio-collared hares fell from 0.27 (1988 – 1990) to 0.07 (1990 – 1991). Annual survival on the 3 extinction sites averaged just 0.015 compared with 0.179 elsewhere. Reproduction did not differ between small (5 – 7 ha) vs. larger (23 – 28 ha) patches nor between years. Estimated dispersal of adult and juvenile hares from the 5 small study areas was twice as high as from the 2 larger, viz. 16 vs. 35% annually. Dispersers appeared to have markedly lower survival. Predation, chiefly by coyotes (Canis latrans), was the proximate cause of 96% (117 of 122) of natural deaths among radio-collared hares, and was therefore the overwhelming determinant of survival and thus population trend. Results of this study suggest that probabilities of extinction in such fragmented habitat depend importantly on patch size and attendant hare numbers; i.e., fall populations of < 10 hares frequenting patches of prime habitat ≤ 5 ha are not likely to persist long without ingress.
An experimental study of the effect of colony resource level manipulation on foraging for pollen by worker bumble bees (Hymenoptera: Apidae)
Authors: Plowright R. C. , Thomson James D. , Lefkovitch L. P. , Plowright C. M. S.
Published: July 2008

Two free-foraging colonies of Bombus terricola Kirby were stressed, on alternate days, by removing either their honey or their pollen stores. The amount of pollen taken into the colonies by foragers was significantly greater under pollen stress than under honey stress. This effect was not due to an increase in the number of foraging trips but rather to an elevated rate of pollen acquisition per foraging trip.
Seasonal patterns in body mass, body composition, and water transfer rates of free-ranging and captive black-tailed deer (Odocoileus hemionus sitkensis) in Alaska
Authors: Parker Katherine L. , Gillingham Michael P. , Hanley Thomas A. , Robbins Charles T.
Published: July 2008

Body mass, body composition, and water transfer rates were determined over a continuous 2-year period in nine free-ranging Sitka black-tailed deer (Odocoileus hemionus sitkensis). Body masses showed a cyclical pattern, declined 14 – 31% between October and March, and were best described by a five-parameter, biologically based regression model. The amount of mass lost by black-tailed deer over winter depended on the peak body mass attained during fall. During winter, animals used 70 – 82% of their body fat and 10 – 15% of their protein reserves. Body fat was preferentially mobilized at rates 2.3 – 11.6 times higher than protein. Because of the higher energy content of fat, fat accounted for 83 – 92% of the catabolized energy. Water transfer rates varied seasonally with average summer values approximately four times those of winter; lactating deer had significantly higher rates of water transfer than nonlactating animals. Seasonal changes in all of the above parameters for wild deer were greater than those for eight deer of the same age in captivity.
Duration of lactation and postweaning changes in mass and body composition of harbour seal, Phoca vitulina, pups
Authors: Muelbert M. M. C. , Bowen W. D.
Published: July 2008

We studied changes in body mass and body composition of harbour seal pups from weaning to 5 – 6 weeks postweaning in June – August 1988 and 1989 on Sable Island, Canada. Known-age pups (n = 52) were captured at 3-day intervals from late lactation through about 40 days postweaning. Pups were weaned, on average, at 24.1 ± 0.44 days (mean ± SE) postpartum at a body mass of 24.9 ± 0.45 kg. There were no significant differences between years or sexes in the age and mass at weaning or in the rate of mass loss during the postweaning period. The duration of the postweaning fast averaged from 15 – 17 days as assessed by stomach lavage. The rate of mass loss was independent of weaning mass. At weaning, pups contained an average of 47.7% water and 32.8% fat, based on deuterium oxide dilution. During the first 14 days postweaning, the estimated body composition of pups did not change, despite the loss of body mass. Over the next 26 days, the estimated percent body water increased to about 63% and body fat declined to about 12%. The average energy density of harbour seal pups at weaning was low (16.3 kJ/g) compared with that of other phocids (17.7 – 22.2 kJ/g). This low energy density at weaning may reflect the highly aquatic and precocial development of harbour seal pups.
Winter feeding strategies of migrating and nonmigrating moose
Authors: Histøl Trond , Hjeljord Olav
Published: July 2008

We recorded forage and habitat use by radio-collared moose, Alces alces (L.), in southeastern Norway. Migrating and resident moose preferred different habitats during winter. Migrating animals used habitats of lower site quality than did resident animals. Migrating animals also used Scots pine (Pinus silvestris L.) forests more often and had a higher proportion of pine and common birch (Betula pubescens L.) in their diet than did resident animals. Increased browsing pressure from both migrating and resident animals was evident at the end of the winter from an increase in twig diameter at the point of browsing, breakage of stems, heavy browsing of common birch, and more extensive searching for forage. Rebrowsing of previously browsed trees by resident moose and, to a lesser extent, by migrants was recorded during March. Snow depths were similar on the winter ranges of resident and migrating moose.
Effect of climatic variation on reproduction by pallid bats (Antrozous pallidus)
Authors: Lewis Susan E.
Published: July 2008

Bats are unusual among mammals in having the ability to respond to fluctuating climatic conditions by employing either a homeothermic or a heterothermic strategy. Low temperatures affect insectivorous bats by increasing the energy required for homeothermy while roosting and by decreasing the energy available due to lower activity of insect prey. Low temperatures may be particularly costly to pregnant and lactating bats because these experience greater energetic demands due to gestation and milk production. The use of heterothermy may increase gestation length and decrease milk production. In a 2-year study of female pallid bats (Antrozous pallidus) in central Oregon, I found that lower spring temperatures in 1991 than in 1990 were correlated with a higher percentage of nonreproductive females, delayed parturition dates, reduced synchrony of parturition, and lower body mass of lactating females. Overall reproductive success was probably lower in 1991 as a result of females not reproducing or of juvenile mortality. In 1991, both females and juveniles were probably in poorer condition prior to migrating and entering hibernation. The effects of temperature on reproduction in this ground-foraging bat are similar to those documented for aerial insectivorous bats. These results have implications for conservation and management of this species in the northern part of its range.
Megacyclops magnus (Marsh, 1920) (Crustacea, Copepoda) in northern Canada, a comparison with European Megacyclops species
Authors: Einsle Ulrich K.
Published: July 2008

Megacyclops magnus (Marsh, 1920) is redescribed using morphological criteria. A morphometric comparison with European Megacyclops species confirms the validity of this well-characterized species, which has often been synonymized with M. gigas. The relative proportions of the apical spines on the last segment of the P4 endopodite (the inner one being shorter than the outer one) are unique within the genus.