bluuebunny/crossref_metadata_2025 huggingface dataset:
Body fat influences sexual maturation in captive male Belding's ground squirrels
Authors: Holmes Warren G.
Published: March 2009

The influence of white adipose tissue on sexual maturation was investigated in captive-born male Belding's ground squirrels (Spermophilus beldingi). Juveniles were given abundant food during the summer and by fall achieved prehibernation body masses approximating those of sexually mature males. Immediately before being placed in a cold room (5–8 °C, constant darkness) for a 7-month hibernation period, fat was surgically removed (lipectomy) or left intact (sham lipectomy). The following spring, paired testes mass, serum testosterone, and spermatogenesis were monitored, mating tests were conducted, and body fat levels were determined. All three physiological indicators of reproductive status were significantly higher in sham-lipectomized than in lipectomized males, only sham-lipectomized males inseminated females, and body fat levels were significantly higher in sham-lipectomized than in lipectomized males. Thus, sexual maturation was accelerated in male Belding's ground squirrels by providing juveniles abundant food so they achieved body masses typical of adults; body fat was essential for accelerated development. In nature, males may forego reproductive development until they can acquire adequate fat stores to survive hibernation and activate their reproductive system and until they gain social experience important in male–male competition for mates.
Hierarchical development, agonistic behaviours, and growth rates in captive arctic fox
Authors: Wakely L. G. , Mallory F. F.
Published: March 2009

Six arctic fox (Alopex lagopus) kits were captured during July 1985 near Eskimo Point, N.W.T., and housed in large outside pens at Laurentian University, Sudbury, Ontario, Canada. Growth rates indicated that the species is sexually dimorphic: adult males were 7.5% larger than females. Juvenile hierarchies were nonlinear and dominant individuals were associated with neither a particular sex nor weight class. However, after fall equinox when animals had reached adult size, hierarchies became linear, and the dominant individuals were the heaviest males. Analysis of agonistic interactions indicated that the species has a rich repertoire of visual signals, which it employs to denote status and intent. These signals, ranging along a continuum from aggression to appeasement, were employed to maintain hierarchial organization and access to limited resources such as food. The results are discussed in relation to current theories on the sociality and population dynamics of the species.
The reproductive performance of black-billed magpies: is it related to mate choice?
Authors: Komers Petr E. , Boag David A.
Published: March 2009

The influence of age and dominance on measures of reproductive effort were investigated in 26 breeding pairs of captive black-billed magpies, Pica pica. Pairs with adult males constructed nests faster, initiated clutches earlier, and produced larger clutches than pairs with juvenile males. Age of females did not influence these variables. The results suggest that the reproductive output of males varies with age more than that of females. Thus when choosing a mate, females have a wider range of parental quality to choose from than do males. This may explain why females are more discriminant than males in mate choice. Paternal quality of breeding males was tested experimentally. During incubation, adult males searched longer for food, approached a potential predator more closely, and attacked a territory intruder more often than did juvenile males. This suggests that adult males invest more in parental care than juvenile males. It may also be a reason for female preference of adult males. There were no differences in the above variables between dominance classes of males in either age group. However, since competition among individuals was excluded by the captive situation, the significance of dominance status was probably minimized.
Timoniella absita n.sp. (Digenea: Cryptogonimidae) from the saltwater crocodile (Crocodylus porosus Schneider) from Australia
Authors: Blair D. , Brooks D. R. , Purdie J. , Melville L.
Published: March 2009

Timoniella absita n.sp. is described from the intestine of the saltwater crocodile (Crocodylus porosus Schneider) from the Northern Territory of Australia. Timoniella absita is closest to Timoniella unami and Timoniella loossi, but can be distinguished from them by the number of oral spines and the posterior extent and arrangement of vitelline follicles, and possibly by the ratio of oral sucker width to pharynx width and the form of the seminal receptacle. The new species is the first representative of Timoniella to be described from the Indo-Malaysian – Australian region.
Sex ratios of young-of-the-year walleye (Stizostedion vitreum) collected from lakes and rearing ponds of western Canada and northern United States
Authors: Glenn C. L. , Mathias J. A.
Published: March 2009

A total of 2682 young-of-the-year walleye (Stizostedion vitreum) were examined from 26 culture ponds and 5 large lakes to determine whether the sex ratio of cultured populations deviated from 1:1. Fingerlings from the lake populations were examined as a standard for comparison. Application of a χ2 test to pond data indicated that ponds, as a group, had significant deviations. Three of the ponds produced significantly more females and two of the ponds produced significantly more males. Neither the grouped nor the individual data from lakes produced sex ratios that deviated significantly from 1:1. Environmental factors such as pond size, depth, stocking rates, or time did not seem to influence sex determination.
Intraguild predation and competition: an analysis of net growth shifts in larval amphibian prey
Authors: Cortwright Spencer A.
Published: March 2009

This study examines the net shift in prey growth among species of aquatic salamander larvae (Ambystoma) that engage in intraguild prédation and competition with their predators. Larval salamander and frog species were studied in a pen experiment in a natural pond. A 2 × 3 factorial experimental design was used. The factors were (i) the presence (11 per pen) or absence of Ambystoma opacum predators, and (ii) three levels of Ambystoma jeffersonianum (42, 84, and 168 per pen), a prey species that also shares resources with A. opacum. All other species were stocked at constant levels. Mass at metamorphosis of A. jeffersonianum was not affected by predator presence. The larval period of A. jeffersonianum (prey) decreased by 20 d in the presence of A. opacum (predators), suggesting enhanced differentiation rate when predators reduced prey populations. Ambystoma maculatum (another prey species) showed no growth responses across experimental treatments, probably because it faced predation from both A. opacum and A. jeffersonianum. A previous study showed that in the absence of both A. opacum and A. jeffersonianum predators, A. maculatum prey manifested reduced mass at metamorphosis. Thus, among these predators and prey, which share resources, the enhanced differentiation rate or larger metamorphic size that prey experienced in reduced prey populations was more important than any negative impact of depressed shared resource levels among predators and prey.
Sympatry in four species of Rhinichthys (Pisces), including the first documented occurrences of R. umatilla in the Canadian drainages of the Columbia River
Authors: Peden Alex E. , Hughes Grant W.
Published: March 2009

Four species of Rhinichthys (R. cataractae, R. falcatus, R. osculus, and R. umatilla) are recognized in Canadian sections of the Columbia River, with sympatry occuring between all species except R. falcatus and R. osculus. Species status of the latter is supported by morphological dissimilarity between it and the morphologically similar R. falcatus and R. umatilla. Populations of R. umatilla from the Similkameen, Kettle, and Columbia (including Kootenay and Slocan) rivers have morphological and pigmentary differences, but are identifiable with R. umatilla of the lower Columbia River. Canadian R. osculus are similar to historically known populations near the Colville and Little Spokane rivers of northeastern Washington. Populations from more distant tributaries of the Columbia system are variable in morphology and habitat and require separate study to determine their relationships to Canadian populations. Rhinichthys osculus was apparently replaced by R. umatilla in the Colville River, an event that may have been correlated with historical changes of water quality or flooding by the Roosevelt Reservoir. Because R. umatilla prefers swift clear portions of large rivers, it is potentially in conflict with hydroelectric projects. Though not immediately threatened, the status of this species in Canada should be monitored in connection with future development of river systems.
Thylacicleidus serendipitus n.gen., n.sp. (Monogenea: Ancyrocephalidae) from the Indonesian freshwater puffer Tetraodon fluviatilis (Tetraodontiformes: Tetraodontidae)
Authors: Wheeler Terry A. , Klassen G. J.
Published: March 2009

Thylacicleidus serendipitus n.gen., n.sp. is proposed for material from the green puffer, Tetraodon fluviatilis Hamilton-Buchanan, 1822, from Indonesia. Thylacicleidus is distinguished from other ancyrocephalid genera by the following combination of characters: a distinctive tegumentary structure, with the body surface covered with numerous small transverse ridges; a sinistral vaginal opening; hamuli with a shortened shaft and heavy blade; ventral hamuli with reduced deep root; ventral transverse bar with lateral extremities sharply deflected posteriorly; and an association with hosts of the family Tetraodontidae. The only ancyrocephalid genus previously recorded from tetraodontids is Haliotrema Johnston and Tiegs, 1922. The status of Haliotrema is discussed and it is suggested that, because of morphological variability within Haliotrema and an extremely wide host spectrum, the genus is almost certainly polyphyletic and in need of taxonomic revision.
Some sources of variation in the elemental composition of Bald Eagle feathers
Authors: Bortolotti Gary R. , Barlow Jon C.
Published: March 2009

Concentrations of Br, Mn, Na, Al, and Cl were measured in back and tail feathers and concentrations of Mg and Ca were measured in tail feathers of wild and captive Bald Eagles (Haliaeetus leucocephalus) using instrumental neutron activation analysis. Feather chemistry of four eagles sampled over 3 years showed considerable annual variation. The profiles of tail feathers, however, appeared distinct for each individual. The mineral profiles of feathers of wild nestlings were usually significantly variable among years. A sex difference was evident for Cl, and perhaps Br and Na, in back feathers of nestlings. Mn and Al concentrations were significantly influenced by the species of prey on which the eaglets had fed. Variation attributable to sex likely has a physiological basis, while much of annual variation can likely be explained by diet.
The karyotype of Sorex arcticus maritimensis (Insectivora, Soricidae) and its systematic implications
Authors: Volobouev V. T. , Zyll de Jong C. G. van
Published: March 2009

The chromosomes of Sorex arcticus maritimensis are described for the first time and their banding pattern (R- and C-bands) compared with those of Sorex araneus. The results provide further evidence for the monophyletic origin of the araneus–arcticus group and clearly indicate that the primary mechanisms of chromosomal reorganization in this group have been Robertsonian and tandem translocations. The basic karyotype of S. a. maritimensis was found to differ from that of S. a. arcticus in having a different fundamental number (34 vs. 38) but the same diploid number. A full understanding of the karyotypic differences between these taxa requires further work. Whatever the exact nature of the differences, they increase the likelihood of an independent specific status for S. a. maritimensis as suggested by the results of an earlier morphometric analysis.
Motor and predatory behavior of Litonotus lamella (Protozoa, Ciliata)
Authors: Ricci N. , Verni F.
Published: March 2009

The ethogram of Litonotus lamella is described and discussed. Individuals of the species creep on the substrate at a velocity of 189 ± 40 μm/s, moving toward the right along geometrically perfect arcs with different radii, lengths, and amplitudes. The arcs are connected by four types of reaction: the continuous trajectory change, the smooth trajectory change, the rough trajectory change, and the side-stepping reaction. Litonotus lamella swims along a helicoid, keeping its ciliated surface outwards. Under appropriate conditions, L. lamella kills, engulfs, and eats the ciliate Euplotes crassus. This predatory behavior consists of two different sets of behavioral patterns; the first is part of the normal motor behavior, while the second comprises behavioral patterns performed characteristically and exclusively during the predatory activity.
The potential for vocal signatures in the calls of young hoary bats (Lasiurus cinereus)
Authors: Koehler Catherine E. , Barclay Robert M. R.
Published: March 2009

We examined calls produced by the solitary bat Lasiurus cinereus during mother–young interactions and considered the potential for vocal signatures in the calls of the young. Families of bats were observed in the field at Delta Marsh, Manitoba, and vocalizations were recorded using high-speed ultrasonic recording equipment. Adult female bats and young vocalize primarily during reunions. Variation in duration and maximum and minimum frequency of the calls of young was calculated. The degree of call variation within L. cinereus family units was relatively high and calls produced by different young could not be differentiated. These observations suggest that a vocal signature, which is present in some colonial species of bats such as Myotis lucifugus and which allows auditory discrimination between calling young, is less likely to occur in L. cinereus.
Changes in the visceral morphology of wintering female mallards (Anas platyrhynchos)
Authors: Heitmeyer Mickey E.
Published: March 2009

Gizzard, heart, intestine, kidney, liver, and spleen mass and cecal length were measured from 143 adult female mallards (Anas platyrhynchos) collected during the winters of 1981 – 1983 in the Mingo Basin of southeastern Missouri. All visceral organs of female mallards changed over winter and seemed responsive, and adaptive, to changes in nutritional and physiological demands attendant with changing annual cycle events. Intestine and gizzard mass and cecal length were greatest during the prealternate moult in early fall and before spring migration, both periods of high total food and fibre intake. Kidney mass was also highest during periods when females foraged intensively and may have reflected the need to excrete large quantities of metabolic by-products. Liver mass increased at the initiation of the prebasic moult and immediately before spring migration, probably in response to increased intermediary metabolism of both proteins and lipids. Spleen mass increased during moult periods and probably facilitated increased blood production and circulation associated with feather development. Heart mass was low in fall and high during the prebasic moult and before spring migration.
Inefficient predators and prey injuries in a population of giant stickleback
Authors: Reimchen T. E.
Published: March 2009

I describe predator-induced injuries in a lake population of large-bodied Gasterosteus aculeatus from the Queen Charlotte Islands, British Columbia. Injuries, which included structural damage (fractured dorsal and pelvic spines) and skin lacerations (scars, abrasions, and punctures), were observed on 13.4% of the population. Bill imprints ("aviscars") from avian piscivores, including Podiceps grisegena and Gavia immer, occurred on one-third of the injured fish. Mean aviscar width (4.2 mm) was low in winter and higher in midsummer correlating with seasonal differences in the presence of avian taxa. One-half of the injured fish had fractured spines without any associated skin damage; sources of these injuries could not be verified although they probably resulted from avian piscivores and resident salmonids. Rate of spine regeneration, determined on artifically marked fish, was 1.09 mm over 26 months. Age of injuries, assessed by condition and regrowth of spines, included recent attacks (ca. 1 month or less, 6.3%) and old attacks (1–3 years, 40%). Thirty percent of skin injuries are undetectable after 1 year. Injuries were absent on juvenile fish (< 50 mm) but were common on adults, reaching an incidence of 32% on sub-samples of the largest fish (> 82 mm). These data are consistent with theoretical predictions of increased manipulation inefficiencies among gape-limited predators and can account in part for the evolution of large body size in this population. Mark–recapture studies on 12 272 adult stickleback (> 70 mm) showed that the probability of incurring a predator injury as an adult fish (0.09/year) is largely a consequence of total length of time in the population; this finding amplifies size-dependent trends in injury frequencies.
The round stingray, Urolophus halleri (Rajiformes: Dasyatidae), as a host for Eimeria chollaensis sp.nov. (Apicomplexa: Eimeriidae)
Authors: Upton Steve J. , Gardner Scott Lyell , Duszynski Donald W.
Published: March 2009

Eimeria chollaensis sp.nov. (Apicomplexa: Eimeriidae) is described from the contents of the spiral valve of the round stingray, Urolophus halleri Cooper (Rajiformes: Dasyatidae), from the Gulf of California, Sonora, Mexico. Oocysts are ovoid, 13.3 × 9.7 (11.2–16.0 × 8.0–10.8) μm, with a smooth, thin, single-layered wall. Micropyle, polar granule, and oocyst residuum are absent. Sporocysts are ovoid, 8.9 × 4.9 (8.0–10.0 × 4.2–5.6) μm, and possess a Stieda body but no substieda body. Sporozoites are elongate, with numerous transverse striations anteriorly and a single, ovoid refractile body. The sporocyst residuum consists of a compact spherical mass 2.5 (2.0–3.4) μm in diameter.
Forage quality and use of reforested habitats by snowshoe hares
Authors: Rogowitz Gordon L.
Published: March 2009

The forage quality of habitats associated with mature conifer plantations and the use of these habitats by resident snowshoe hares (Lepus americanus) were evaluated. The winter forage of hares was composed of deciduous stems that were predominantly low in protein content and not preferred. The crude protein content of the principal browse species, Viburnum dentatum, was only 4.6–6.4% during winter months. However, snowshoe hares feeding on the low-protein browse maintained their body weight. The intake of protein was maximized by the consumption of stem ends, which compensated for the low-protein forage. Use of habitat by snowshoe hares was closely related to the vegetative cover but did not correlate well with forage availability. Sites preferred by hares had a well-developed overstory (mature spruce) but only sparsely available forage during the winter. Thickets of early-successional deciduous vegetation had high use and contained most of the low-protein browse.
Identifying the time scale of temporal association
Authors: Burt Austin , Hunte Wayne , Dufresne France
Published: March 2009

Previously used methods of investigating the temporal association of behavioural events have tested sequences of events for temporal clumping; such an approach does not quantitatively indicate the time scale over which the association is significant. We present a novel method of analysis that specifically identifies this time scale, thereby allowing more ready elimination of competing causal hypotheses for the association observed. Our null hypothesis is that, following any event, the number of events in a given time interval is independent of the time elapsed since the initial event. The method is simple and robust against long-term changes in event frequency, and provides a more detailed quantitative description of the temporal association. We illustrate it using data on spawning in the blueheaded wrasse (Thalassoma bifasciatum). The analysis demonstrates that, after a spawning event, there is a 70% increase in mean spawning frequency which lasts for 30 s and then abruptly disappears. The effect of spawns appears to summate multiplicatively.
Cyclops canadensis n.sp. and Cyclops scutifer Sars, 1863 (Crustacea: Copepoda) from northern Canada
Authors: Einsle Ulrich K.
Published: March 2009

The occurrence and distribution of Cyclops s.str. species (strenuus subgroup) in Canada and the United States has not yet been reliably studied. In this first attempt, Cyclops scutifer Sars, 1863 is characterized, and a new species, Cyclops canadensis, is established. As no cytological investigations were possible, the species are described on the basis of morphological and morphometrical data. Most probably, the new species, Cyclops canadensis, formerly was identified as Cyclops strenuus.
The benefits of communication between comparative ethology and phylogenetic systematics: a case study using gasterosteid fishes
Authors: McLennan D. A. , Brooks Daniel R. , McPhail J. D.
Published: March 2009

Early comparative ethologists stressed both phylogenetic (historical) and environmental (selection) factors when searching for explanations of behavioural evolution. The last two decades have witnessed a narrowing of ethologists' evolutionary perspective to questions concerning environmentally based maintenance of behaviours. This approach, with its reliance on subjective, a priori assumptions concerning the temporal sequence of ethological modifications, dissociates character evolution from underlying phylogenetic relationships. This, in turn, is responsible for the tendency of many researchers to confuse character maintenance (stasis) with character origin and divergence (evolution). The decline of phylogenetically based explanations of behavioural evolution is mirrored by the decline in the utilization of behavioural data in systematic analyses. Yet, since behaviour is closely intertwined with development, physiology, and morphology and thus subject to the same evolutionary processes and constraints, it should change in ways that reflect underlying phylogenetic relationships. Communication between comparative ethologists and systematists is restricted. As an example of the potential benefits of interdisciplinary communication, a phylogenetic systematic analysis of the teleostean family Gasterosteidae (sticklebacks) based solely upon behavioural characters is presented. The phylogenetic tree derived from this analysis has a consistency index of 90.3%. In this particular case, the behavioural data provide a less ambiguous picture than the morphological data. The phylogenetic tree, in turn, is a hypothesis of the temporal sequence of behavioural evolution. From this hypothesis, it is possible to trace the origin, divergence, and interrelationships of agonistic, sexual, and parental behaviours in gasterosteids, and to compare this macroevolutionary patterning with predictions of character evolution based on microevolutionary studies. Examination of behavioural evolution within a phylogenetic framework provides a more robust characterization of evolutionary history. By analyzing and comparing structural (biochemical, morphological) and functional (ecological, behavioural) aspects of the phenotype, future phylogenetic studies will enable us to develop a more comprehensive picture of the patterns of biological evolution.
Mate choice in American Redstarts: by territory quality?
Authors: Morris Michael M. J. , Lemon Robert E.
Published: March 2009

We consider the hypothesis that mate choice in American Redstarts (Setophaga ruticilla) depends primarily on features of territories held by males. We test the hypothesis that the territories of yearling males are demonstrably different from and inferior for reproduction to those of adult males. Territories held by the two age-classes in New Brunswick, Canada, were floristically different, but there were also major differences in territorial features in three microgeographic areas, both within each age-group and without regard to age. There were greater differences in nest success between areas than between the age-classes. We detected no differences in immediate nest site features between nests built by the mates of yearling and adult males. There were differences across the three areas in the species of trees used as nest sites, probably reflecting differences in availability. Support for the claim of different reproductive success in relation to quality of territories held by the two age-classes of males is not convincing.
Ecology and natural history of aquatic Talitroidea
Authors: Wildish D. J.
Published: March 2009

A review of the ecology of amphipods belonging to the superfamily Talitroidea (Crustacea, Amphipoda) is presented. Species of Talitroidea are characteristically able to hop by rapid flicks of the urosome. They include land hoppers, which are true land-inhabiting forms excluded from detailed consideration in this review, as well as aquatic Talitroidea. Aquatic Talitroidea are found throughout much of the world in freshwater, estuarine, and marine conditions in littoral and infralittoral habitats, and an ecological habitat classification is presented. Subjects discussed include taxonomy, life history, dispersal, and the ecological factors affecting the survival of shore hoppers. The synecological role of shore hoppers in the aquatic ecosystem, e.g., in mineralizing primary production, is relatively minor although it may be locally important. The evolutionary ecology of land hopper origins from ancestors resembling shore hoppers is discussed, in the absence of direct evidence, based on likely colonization routes suggested by the distribution of contemporary talitroids.
Host–parasite relationships between burbot (Lota lota) and adult Salmincola lotae (Copepoda)
Authors: Lasee Becky A. , Sutherland Daniel R. , Moubry Maryjo E.
Published: March 2009

The pathology elicited by the parasitic copepod Salmincola lotae and its distribution within the oral cavity of the burbot, Lota lota, is described. Of 50 burbot examined from the Apostle Islands region, Lake Superior, near Bayfield, WI, 18 (36%) were infested with S. lotae. A total of 63 copepods were recovered. Burbot were examined from three Lake Michigan collecting sites: 70 from Sturgeon Bay, 9 from Manitowoc, and 60 from Sheboygan were not infested with S. lotae. Salmincola lotae appears to prefer middle regions of the roof of the mouth. Mechanical damage to host tissues resulting from copepod presence included epidermal shredding from parasite feeding and lesions from bulla excavation and implantation. Epidermal encapsulation of the second maxillae of S. lotae was the primary host tissue reaction. Increased dermal vascularization and leucocyte infiltration occurred in regions of parasite attachment. This is the first report of S. lotae from the Nearctic.
Adaptations of Coleoptera to the marine environment. I. Observations on rove beetles (Staphylinidae) from sandy beaches
Authors: Topp Werner , Ring Richard A.
Published: March 2009

The sandy beaches of British Columbia are inhabited by a small number (11 species) of indigenous Staphylinidae which live near the drift line in the mid to upper littoral zone. They prefer fine-grained sandy beaches and most species feed on other intertidal invertebrates. All species investigated survived submersion in seawater by becoming quiescent, thereby reducing their metabolic rate. Oxygen consumption in seawater was greatly reduced. On re-exposure to air, a large overshoot in oxygen consumption occurred (in Thinopinus pictus), signifying a prior oxygen debt. In Cafius canescens, Cafius seminitens, and Hadrotes crassus the time required to reach full recovery was directly related to the duration of submersion, with 50% mortality in the population when recovery time exceeded 25 min. At a seawater temperature of 10 °C, LT50 was reached at 12–16 h submersion and at 20 °C, after 6.5 h. In Thinopinus pictus, however, recovery time was independent of duration of submersion, although the mortality curves were almost the same as for the three previously mentioned species, with LT50 occurring at 13 h at 10 °C and 7–8.5 h at 20 °C. Bledius monstratus showed symptoms of oxygen depletion only after a considerable time lag. Experimental submersion of this beetle resulted in an LT50 of 18 h at 20 °C.
The swim response of the actinian Stomphia didemon to certain asteroids: distributional and phylogenetic implications
Authors: Dalby Jr. J. E. , Elliott J. K. , Ross D. M.
Published: March 2009

Nine of 17 asteroid species in the Barkley Sound region of Vancouver Island cause the actinian Stomphia didemon to release its pedal disk and swim. Only the asteroid Dermasterias imbricata was identified as a predator of the anemone. In the laboratory two asteroid species interacted with S. didemon, including D. imbricata, which interacted with the anemone in the field. On rocky slopes, staged interactions with asteroids caused S. didemon to move to greater depths. This movement may contribute to the disproportionately low abundance of S. didemon in shallow water where asteroid abundance is high. That S. didemon shows the response to asteroid species that are not its predators may reflect phylogenetic affinities that exist between these asteroids and the predator D. imbricata.
Diel patterns of activity and substrate preference in young Arctic char from the Koroc River, northern Quebec
Authors: Adams N. J. , Barton D. R. , Cunjak R. A. , Power G. , Riley S. C.
Published: March 2009

Young Arctic char (Salvelinus alpinus) were observed in a stream tank located on the bank of the Koroc river, northern Quebec. Early in the summer, char were most active from dusk to dawn, and at midday, mainly over gravel or sand. Some nocturnal feeding activity was evident. As the summer progressed, this diel periodicity in activity became less pronounced; char exhibited increasing diurnal activity, most of it over rubble substrata. Char preferred rubble for resting throughout the summer. Invertebrate drift decreased from July through August so that, although fish were active more of the time, the rate of feeding during periods of activity declined.
A view of niche overlap amenable to statistical analysis
Authors: Linton L. R. , Edgington E. S. , Davies Ronald W.
Published: March 2009

Published values of niche overlap (similarity) are generally point estimates of the similarity between population centroids. A number of shortcomings are associated with this method of data presentation: (i) confidence intervals on the estimates are lacking, (ii) no statistical procedures are used to test for significant differences between estimates, and (iii) the estimates tend to be biased. These problems arise primarily as a result of the manner in which data are pooled for the calculations. We illustrate an alternative method of data handling, involving calculation of similarity between individuals, which is more biologically reasonable and which eliminates these problems. A permutation test procedure is also introduced for use on large sets of data.
Body composition of the George River caribou (Rangifer tarandus caribou) in fall and late winter
Authors: Huot J.
Published: March 2009

The fall and late winter body composition of George River caribou was determined based on a sample of 14 calves, 9 yearlings, and 41 adult females. In fall, the fattest individuals were the adult nonlactating females with 10.62 ± 2.65% ingesta-free body fat. Ingesta-free body fat was 5.25 ± 2.47% for lactating females, 7.76 ± 0.11% for yearlings, and 3.44 ± 0.57% for calves. There was no evidence of depletion of fat reserves between fall (October–December) and mid-April in any age-class, and no change in body weights of calves. However, the ingesta-free body weights of pregnant females in April were 19.8 and 9.5% less than those of nonlactating and lactating females in fall, respectively. These differences were due mainly to a loss of water (9.8 and 7.3 kg) and protein (4.6 and 2.6 kg). This protein loss of the ingesta-free body was not compensated for by growth of the gravid uterus, which accounted for 3.5% (0.53 kg) of the total protein mass of pregnant females in mid-April. These results suggest that, between fall and late winter, the George River caribou were affected more by a deficiency in protein than a negative energy budget and that increased attention should be given to monitor protein reserves. However, in summer and early fall, these caribou accumulated only limited fat reserves as compared with other northern ungulates and the possibility of an energy deficiency during summer should be investigated.
Morphology of the mesosoma of Kapala (Hymenoptera: Eucharitidae) with emphasis on its phylogenetic implications
Authors: Heraty John M.
Published: March 2009

The skeletomusculature of the highly derived mesosoma of Kapala (Eucharitidae: Eucharitinae) is described with particular reference to the pronotal – prepectal complex, mesoscutum, and scutellar – axillar complex. Orasema (Eucharitidae: Oraseminae) was used for outgroup comparisons based on polarization of certain character states as plesiomorphic through comparisons with Perilampidae and Pteromalidae. Dilocantha, Pseudochalcura, Schizaspidia, and Stilbula were used as ingroups for analysis of structures within Eucharitinae. Several character states are discussed with regard to their use in determining relationships within Eucharitinae and a cladogram is presented for six genera. Autapomorphies discussed for the subfamily Eucharitinae are fusion of the prepectus to the pronotum, mesothoracic spiracle completely enclosed dorsally, lack of anterior ventral inflection of the mesoscutum behind the pronotum, and transverse axillae associated with a well-developed transverse internal ridge along the scutoscutellar sulcus. Synapomorphies proposed for Kapala and related taxa in the New World include the reduced lateral axillar surface, internal ridge of the scutoscutellar sulcus developed as an internal phragma, posterior scutellar spines of common derivation, and structure of the internal pronotal–prepectal complex.
Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) in the northern Gulf of St. Lawrence
Authors: Dutil J.-D. , Michaud M. , Giroux A.
Published: March 2009

Seasonal and diel patterns of stream invasion by American eels (Anguilla rostrata) were monitored in a small stream located on the north shore of the Gulf of St. Lawrence from 1981 to 1985. Glass eels and elvers migrated from the sea in late June and July. Glass eels made up only a small percentage of the migrants. Pigmentation progressed quickly in the estuary, but elvers grew very slowly. Migration from the estuary and through the lower reaches of the stream was slow; no glass eels or elvers occurred at a station located only 4 km from saltwater. Juvenile eels reached that station in their second summer of stream residence. Juvenile eels migrated in July and August. They ranged from 70 to 250 mm in length and included more than one age-class. Those less than 100 mm in length were most numerous. Relative abundance of glass eels and elvers decreased in the estuary from 1981 to 1985. This coincided with a decrease in the proportion of smaller sized eels in the stream migration over the same period. Juvenile eels migrated progressively later in summer as the proportion of smaller sized eels decreased. Stream migration was nocturnal. Movements mainly occurred between 21:00 and 23:00. The relationship between glass eel and elver abundance in the estuary and juvenile eel abundance in the stream 1 and 2 years later was not clear.
The effects of various maintenance conditions on the survival of hymenolepidid cysticercoids
Authors: Evans William S. , McKenzie Ceayon , Novak Marie , Howlader Hatem
Published: March 2009

Cysticercoids of Hymenolepis microstoma, Hymenolepis nana, and Hymenolepis diminuta were examined for their ability to excyst in vitro after being stored in balanced salt solution, distilled water, or the bodies of dead hosts (Tribolium confusum). The number capable of excysting decreased as the duration of the storage period was increased but the rate of decrease varied with the storage medium and was invariably slower when the parasites were stored at 4 °C than when they were kept at 22 °C. The combination of storage medium and temperature that produced the slowest rate of decrease in the ability of the parasites to excyst varied according to species.
Seasonal differences in habitat use and fat reserves in an arctic muskrat population
Authors: Jelinski Dennis E.
Published: March 2009

Differences in summer and winter habitat use by muskrats (Ondatra zibethicus) were studied in the Mackenzie River Delta, Northwest Territories, Canada. Quantitative data consisting of 11 habitat variables were obtained from 73 winter and 119 summer burrow sites. The single discriminant function derived from a discriminant function analysis of summer and winter burrow sites was strongly correlated with variables interpreted as describing food, cover, and overwinter survival of muskrats. During summer, muskrat burrows were closer to shallow water, on gentler slopes with greater cover, and occurred closer to stands of horsetail (Equisetum fluviatile) than in winter. Food habit analyses revealed that high-protein E. fluviatile was the most frequently consumed species in summer. Muskrats of both sexes were found to enter the breeding season in extremely good condition when judged on the basis of body fat; the costs of breeding, lactation, and resource defense are hypothesized to account for the low-fat condition noted at the onset of winter. Prior to winter, muskrats relocated to deep-water sites, possibly to maintain access to food and (or) forage on the energy-rich roots and rhizomes of submerged macrophytes. The change in habitat use, coupled with physiological adaptations to cold, is suggested to account for the winter recovery in fat reserves. These same reserves can be mobilized in spring at the onset of the metabolically demanding breeding season.
A description of the ultrastructure of the gills of freshwater bivalves, including a new structure, the frontal cirrus
Authors: Way Carl M. , Hornbach Daniel J. , Deneka Tony , Whitehead Russell A.
Published: March 2009

The archetypical gill structure of lamellibranch bivalves has been the focus of research concerning the feeding mechanisms of these clams. In recent years there has been debate over whether the lamellibranch gill acts as a sieve or whether the gill ciliature produces hydromechanical shear forces for the capture of particles during feeding. In corbiculacean bivalves, the gill shows considerable interspecific variability in the integrity of the ciliary tracts. A novel ciliary structure, the frontal cirrus that varies in organization, distribution, and abundance in the three species studied, has been found. In Musculium transversum the cirri are found only on the outermost margins of the inner demibranch and are composed of a tight bundle of cilia originating on the posterior side of the gill filament. The cirri in Corbicula fluminea appear as either a tight bundle or a loose aggregate of cilia, originating on the posterior side of the gill filament between the frontal cilia and the laterofrontal cirri; the frontal cirri cover the entire demibranch except in the area near the food groove. The frontal cirri in Polymesoda caroliniana are similar in structure and distribution to those found in C. fluminea. The frontal cirri are hypothesized to play an important role in the feeding physiology of these bivalves.
The adaptive significance of crèching behaviour in the white-winged scoter (Melanitta fusca deglandi)
Authors: Kehoe F. Patrick
Published: March 2009

I tested several hypotheses regarding the adaptive significance of crèching behaviour using white-winged scoters (Melanitta fusca delgnadi) at Redberry Lake, Saskatchewan. Scoter crèches consist of a single female tending the young of one or more conspecifics. There was no relationship between a female's weight at the end of incubation and whether she stayed with ducklings. Therefore, there is no evidence that females in poor condition abandon their young more frequently than other females. No relationship was found between a female's age and her association with ducklings. Therefore, crèching does not appear to be related to female age or experience. Observations of color-marked ducklings in 1985 showed that 7 out of 10 females tended crèches that were composed entirely of fostered young. The survival of ducklings from large groups was greater than that from small groups, so crèching does not appear to be a strategy that enhances individual fitness of crèche-tending females. However, because of the high degree of philopatry displayed by female scoters, crèching could enhance inclusive fitness if crèches contain the young of related individuals. This hypothesis could not be tested.
Crawling behaviour of the amphipod Corophium volutator and foraging by Semipalmated Sandpipers, Calidris pusilla
Authors: Boates J. Sherman , Smith Peter C.
Published: March 2009

During late spring and summer, the crawling behaviour of the amphipod Corophium volutator was studied on an intertidal mudflat in the Minas Basin, Nova Scotia. On average, less than 1% of the population crawled on any tide and these individuals tended to be large adults that were predominantly males. Animals emerged as the tide receded but most had crawled into burrows after 25 min. The crawling behaviour did not seem to be related to the lunar cycle as was expected; however, there was a sharp reduction in crawling activity (from 36.3 to 1.2 amphipods/m2) in July that coincided with the arrival of Semipalmated Sandpipers, Calidris pusilla, an abundant seasonal predator. The proportion of males in the amphipod population declined during the period when sandpipers were present. It appears that both a change in amphipod behaviour and depletion of the animals most prone to crawling may contribute to the observed reduction in crawling activity. Qualitative and quantitative evidence show that sandpipers were attracted to the tide edge where crawling amphipods were relatively abundant and that they increased their food intake by doing so.
Response of the white-footed mouse (Peromyscus leucopus) to the transition between disturbed and undisturbed habitats
Authors: Linzey Alicia V.
Published: March 2009

The relationship between social behavior, demography, and habitat selection in the white-footed mouse (Peromyscus leucopus) was studied at the transition zone between disturbed (clear-cutting and strip-mine) and undisturbed (woodland) habitats. Demographic characteristics included a tendency toward overrepresentation of young mice (juvenile and subadults) in disturbed habitats and higher disappearance rates for young woodland males than for females. Home range data indicated that movements between habitats were minimal and mostly restricted to the ecotone. Behavioral interaction studies revealed that woodland mice were more likely to initiate contact and that mice from the clear-cutting responded by retreating or fleeing. During a reciprocal removal experiment, 43% of the resident population of the clear-cutting moved to woodland habitat after the original woodland population had been removed; no residents of woodland habitat moved to a disturbed site following removal. The suggestion that disturbed habitats serve as dispersal sinks for behaviorally subordinate individuals is supported by these data.
Body mass dynamics of wood ducks during incubation: individual variation
Authors: Harvey IV William F. , Hepp Gary R. , Kennamer Robert A.
Published: March 2009

Female wood ducks (n = 72) lost on average 1.3 ± 0.1 g/day during incubation. Change in body mass varied greatly among females (CV = 93%); it ranged from individuals that gained body mass to those that lost > 4 g/day. Loss of body mass was directly related to body mass of females in early incubation, but not to time of nesting, age, or clutch mass. Incubating hens lost mass at a greater rate in 1986 (1.9 ± 0.2 g/day) than in 1987 (1.2 ± 0.2 g/day), possibly because drought conditions in 1986 reduced foraging areas. For individuals sampled in both years of the study (n = 14), the group average of early incubation body mass and rate of mass change during incubation were similar between years. However, while similarity of body mass for individual females at the start of incubation was high between years (repeatability 82%), it was low for body mass changes that occurred during incubation (repeatability 31%). Thus, although change in body mass was related to the body mass at which hens began incubation, other factors must also have been involved.
Sarsia cliffordi n.sp. (Cnidaria, Hydrozoa, Anthomedusae) from British Columbia, with distribution records and evaluation of related species
Authors: Brinckmann-Voss A.
Published: March 2009

The life cycle of a new hydrozoan species, Sarsia cliffordi, is described from British Columbia. The systematic characters of related species, Sarsia eximia, S. radiata, S. producta, S. japonica, and two undescribed species, are reviewed. Sarsia producta is reported from the western Atlantic for the first time.
The Simulium metallicum species complex (Diptera: Simuliidae) in Latin America: a cytological study
Authors: Conn Jan , Rothfels K. H. , Procunier W. S. , Hirai H.
Published: March 2009

Eleven members of the Simulium metallicum complex from Central America and South America are described using the polytene chromosome banding pattern of S. metallicum A as standard. The members are B from Mexico and Guatemala, C from Colombia, D and E from Venezuela, F from Panama, G from Costa Rica, H from Mexico, Guatemala, and Panama, I from Mexico and Guatemala, and J and K from Panama. A cytophylogeny separates the members into three lineages. H, I, J, and K form one lineage, separated from the standard by eight rearrangement steps. D and E form a second lineage on the basis of six fixed inversions in common. Three floating inversions characterize the common progenitor of C and G, which together form a third lineage. B is independently derived from the standard and separated from it by seven rearrangement steps. F is very close to A. Six cytotypes (A, B, H, I, J, and K) appear cytologically to be reproductively isolated and are considered sibling species. One cytotype, E, is a sibling species by virtue of cytological criteria, and possible ecological and physiological factors. The remaining four members (C, D, F, and G) are cytotypes requiring additional evidence to confirm sibling species status. Sibling A is provisionally considered to represent S. metallicum s.s.; sibling H may be S. horacioi Okazawa &Onishi. The status of members within the complex as vectors of Onchocerca volvulus is discussed.
Influence of the type of territorial intruder on the aggressive response of Ring-billed Gulls
Authors: Dulude Anne-Marie , Baron Georg , McNeil Raymond
Published: March 2009

The influence of the type of territorial intruder on the aggressive response of adult Ring-billed Gulls (Larus delawarensis) was studied by observation of pairs breeding in the periphery of a colony in southern Quebec. The jab was the most frequently exhibited agonistic behavior. The majority of agonistic patterns, except attacks during the post-hatch period, were directed toward adults. Most agonistic behavior was directed against neighboring rather than non-neighboring adults; only charges were directed more often against non-neighboring than against neighboring adults. Agonistic interactions on the whole were more frequent during the post-hatch period and non-neighboring chicks suffered more aggressive acts than neighboring ones; this was apparently related to the fact that non-neighboring young were more mobile and more likely to steal food.