bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of anoxia exposure and aerobic recovery on metabolic enzyme activities in the freshwater turtleTrachemys scripta elegans
Authors: Willmore William G , Cowan Kyra J , Storey Kenneth B
Published: April 2011

The effects of anoxic submergence (20 h at 7°C in nitrogen-bubbled water) and subsequent aerobic recovery (24 h at 7°C) on the maximal activities of 21 metabolic enzymes were assessed in liver, kidney, heart, brain, and red and white skeletal muscle of an anoxia-tolerant freshwater turtle, the red-eared slider, Trachemys scripta elegans. Anoxia exposure affected the activities of only a few enzymes; for example, it reduced the activity of phosphofructokinase in liver and brain, hexokinase in kidney, glycerol-3-phosphate dehydrogenase and glutamate-oxaloacetate transaminase in heart, glutamate dehydrogenase and serine dehydratase in brain, and 3-hydroxyacyl-CoA dehydrogenase in red muscle. During aerobic recovery, activities of most of these enzymes rebounded and activities of 10 others that were not affected by anoxia rose during recovery. Anoxia-induced changes in selected enzymes appear to meet very specific needs such as glycolytic-rate depression, regulation of glycolytic versus gluconeogenic flux in liver, or alterations in amino acid neurotransmitter levels in brain. Overall, the data demonstrate that the enzymatic make-up of turtle organs undergoes very few changes during anoxia exposure and recovery, which shows that the constitutive activities of enzymes are well designed to meet the metabolic demands of anoxic excursions.
Mitochondrial DNA sequence variation and the specific identification of deer mice (Peromyscus) from Triangle Island, British Columbia, Canada
Authors: Chirhart Scott E , Arianpour Roozbeh , Honeycutt Rodney L , Greenbaum Ira F
Published: April 2011

Nucleotide sequences from the ND3, ND4L, and ND4 genes of the mitochondrial DNA of deer mice (Peromyscus) from Triangle Island, British Columbia, were analyzed and compared with those from reference samples of the geographically proximal species Peromyscus maniculatus and Peromyscus keeni. Variation among the deer mice from Triangle Island comprised four sequences with a total sequence divergence of 0.093%. One of these sequences characterized 52% of the 27 individuals analyzed; each of the other sequence variants occurred in smaller, but similar, proportions of the population sample. Phylogenetic and distance-clustering analyses uniformly grouped the sequences from the Triangle Island population and placed them within a cluster otherwise comprised of the P. keeni reference samples. The reference samples of P. maniculatus clustered distinctly and significantly outside of the P. keeni/Triangle Island deer mouse assemblage. These data indicate that, in contradiction to their current formal recognition as P. maniculatus, the deer mice from Triangle Island are representative of, and should be taxonomically relegated to, P. keeni.
STUDIES ON STRONGYLOIDES OF PRIMATES: I. MORPHOLOGY AND LIFE HISTORY OF STRONGYLOIDES FÜLLEBORNI VON LINSTOW, 1905
Authors: Premvati
Published: April 2011

A detailed description is given of the parasitic females and free-living stages of Slrongyloides fiilleborni von Linstow, 1905, from Indian rhesus monkeys.
IDENTIFYING RECENT AND FOSSIL BARNACLES
Authors: Cornwall Ira E.
Published: April 2011

The study of the microstructure of the shells of sessile barnacles shows that in many of them there is a figure, or pattern, that is constant in both recent and fossil shells of the same species and this can be used in identification.It is quite easy to find the pattern in the shell and the method of doing it is fully described in this paper.
PARTHENOGENESIS IN A CYST-FORMING NEMATODE, HETERODERA TRIFOLII (NEMATODA: HETERODERIDAE)
Authors: Mulvey Roland H.
Published: April 2011

The clover cyst nematode, Heterodera trifolii (Goffart, 1932) Raski and Hart, 1953, reproduced in the absence of males. Under greenhouse conditions nematodes reared from single larvae and from mass cyst culture were diploid-parthenogenetic. During maturation only one polar body was produced. The diploid number (24 ?) of chromosomes was not reduced and no male was found.
NOTES ON SOME DICRANOPHORINAE (ROTIFERA)
Authors: Neal G. M.
Published: April 2011

The reliability of certain structures of rotifers used for specific identification is discussed. Dicranophorus uncinalus (Milne) of Harring and Myers has been redesignated as D. aquilus (Gosse) and both species are redescribed. D. uncinalus of Weber (nee Milne) is a member of the D. rostratus-grypus group and D. cernuus Harring and Myers is a synonym of D. rostratus (D.-N. &F.), while D. coryslis H. &M. and D. haueri H. &M. are both valid species distinct from D. rostratus.
EFFECTS OF SYNTHETIC THYROXINE AND GONADAL STEROIDS ON THE METABOLISM OF GOLDFISH
Authors: Hoar William S.
Published: April 2011

Studies of both standard and active metabolism agree with most previous findings that thyroid hormone lacks a calorigenic effect while the gonadal steroids stimulate oxygen consumption. Thyroxine, testosterone, or stilboestrol will produce a marked increase in the excretion of nitrogen as measured by changes in the ammonia of the ambient water.
STUDIES OF THE FEEDING ORIENTATION OF THE JACK PINE SAWFLY, NEODIPRION PRATTI BANKSIANAE ROH.
Authors: Ghent A. W.
Published: April 2011

The heads of feeding larvae of the jack pine sawfly are consistently oriented towards the needle tips. This orientation is not obtained from the apically-directed needle teeth, and is found to be independent of gravity and of the flexibility of the foliage. Though light can act to disrupt the orientation, larvae adopt the orientation in darkness so that light cannot be postulated as an essential directive stimulus. The behavior is identified as a "free-end" response, and possible underlying mechanisms are discussed.
ON THE POPULATION REDUCTION OF CHORIOPTIC MANGE MITES ON CATTLE IN SUMMER
Authors: Sweatman Gordon K.
Published: April 2011

Extrinsic factors appear to be significant in reducing the number of chorioptic mange mites on pastured cattle in summer, and an environmental "change" per se and intraspecific factors may be limiting factors also. Molting, normal desquamation, rubbing, licking, and any physiological skin change are not deleterious factors to a population of C. bovis.
THE EFFECT OF A MICROSPORIDIAN PARASITE ON THE DEVELOPMENT, REPRODUCTION, AND MORTALITY OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.)
Authors: Thomson H. M.
Published: April 2011

Infection of the spruce budworm, Choristoneura fumiferana (Clem.), by the microsporidian parasite Perezia fumiferanae Thorn, retards both larval and pupal development and reduces pupal weight, fecundity, and adult longevity. These effects are more pronounced among the female insects. There is no evidence that the parasite affects male fertility, mate choice, or the fertility of eggs produced. The parasite causes some mortality, most of which occurs before the fifth instar. Among larvae infected orally, mortality seems to be related to the size of the initial dose. Mortality occurs equally in both sexes. The development and survival of the first instar and overwintering second instar are not affected by the parasite. It is suggested that the parasite causes most of the observed results by reducing the insect's ability to assimilate its food. Mortality, however, is believed to be due to the destruction of the mid-gut or Malpighian tubules.
ON SOME HELMINTH PARASITES COLLECTED FROM THE MUSK OX (OVIBOS MOSCHATUS) IN THE THELON GAME SANCTUARY, NORTHWEST TERRITORIES
Authors: Gibbs Harold C. , Tener John S.
Published: April 2011

Three species of nematodes and three species of cestodes are reported from Ovibos moschatus taken in the Thelon Game Sanctuary, N.W.T.
The Nymphomyiidae (Diptera), with special reference to Palaeodipteron walkeri Ide and its larva in Quebec, and a description of a new genus and species from India
Authors: Cutten Felicity E. A. , Kevan D. Keith McE.
Published: April 2011

The literature on the two described species of Nymphomyiidae, Nymphomyia alba Tokunaga and Palaeodipteron walkeri Ide, is reviewed. Previous opinions on the systematic position of the family and what is known or surmised about their biology are outlined. The occurrence of P. walkeri in Canada is discussed and new records are given from a small upland stream in western Quebec. The larvae of Nymphomyiidae were previously unknown, but those of P. walkeri have been discovered. It is confirmed that they are aquatic. Details of habitat of P. walkeri are given, and the larva is described and figured in detail. An outline of the probable bivoltine life history of this species and some further considerations regarding the relationships of the Nymphomyiidae are also made. An appendix makes additional comments on P. walkeri adults and the opportunity is taken by the second author to describe a new genus and species, Felicitomyia brundini, from the eastern Himalaya.
A new species of diaptomid copepod from Saskatchewan with notes on the crustacean community of the pond
Authors: Anderson R. Stewart , Fabris Gary L.
Published: April 2011

Diagnosis of a new species of freshwater copepod of the subgenus Leptodiaptomus is presented. The new species was found in a western Saskatchewan pond with three other Diaptomus species, one cyclopoid copepod, eight cladocerans, one conchostracan, and one ostracode. All of the diaptomid copepods were found to be ovigerous at the same time and few nauplii were found at this time. It seems likely that different food niches, different reproductive rates, and reduced selective pressures in the pond are the most important mechanisms permitting the co-occurreace of four Diaptomus species.
Temperature-dependent characteristics of peripheral nerves exposed to different thermal conditions in the same animal
Authors: Miller L. Keith
Published: April 2011

Beaver (Castor canadensis) caudal nerves, accustomed to tissue temperatures approaching 0 °C, were compared with nerves that encounter less severe cooling (tibial), and nerves that are accustomed only to deep body temperature (phrenic). Caudal nerves invariably conducted action potentials until freezing at about −5 °C. Tibial nerves ceased conducting at 0 °C and phrenic nerves failed at 4.5 °C. Conduction velocity – temperature slopes of the three nerves were different and absolute refractory periods in the cold-adapted nerves were significantly shorter at low temperature. Results furnish additional proof of cold adaptation in peripheral nerve.
Study of fish movements under constant conditions of light and darkness
Authors: Kapoor N. N. , Kleerekoper H.
Published: April 2011

This paper deals with the locomotor movements of four fish species, Salmo gairdnerii irideus Gibbons, Ambloplites rupestris rupestris (Rafinesque), Ictalurus nebulosus nebulosus (Le Sueur), and Lepomis gibbosus (Linnaeus), and the locomotor patterns displayed by non-conditioned animals in constant conditions of light and darkness.The entries into the 16 sectors of the tank were uniformly distributed; there was no preference shown by the fish for any one sector of the experimental tank, regardless of the light condition.Most animals with the exception of the rock bass displayed a definite pattern of locomotor movements, consisting of a range of turning angles. Variations in this pattern were not significant from day to day under similar experimental conditions of light.Frequencies of right- and left-handed turns showed individual differences in a large number of bullhead and pumpkinseed, whereas there were no differences in rock bass. Thigmotaxis and vision might play a role in this turning behavior.Animals displayed a different angular pattern of locomotion under light and dark conditions. Rock bass and pumpkinseed showed a preference for short angle turns whereas rainbow trout made turns of longer angles. Bullhead showed no change in the magnitude of the angles of turn.
Development of the Columbian black-tailed deer (Odocoileus hemionus columbianus) during the fetal period
Authors: Ommundsen Peter , Cowan I. McT.
Published: April 2011

This study of 88 fetuses of the Columbian black-tailed deer (Odocoileus hemionus columbianus) from a single wild-ranging population has yielded values of k in the heterogonic growth formula for 18 measurable attributes. Length measurements of the ear pinna and the elements of the legs have the highest coefficients during prenatal development. This is in marked contrast with circumstances subsequent to birth.There is no evidence of an anterior-posterior trend in growth in diameter of parts of the trunk. In the legs, each component of the hind limb grows faster than the corresponding part of the foreleg. This departs from the patterns of postnatal growth where there is slight anterior precedence.During fetal development, unlike postnatal development, cranial and rostral segments of the skull grow at the same rate.Regional variation in growth rate of different body parts is extensive and even in twin pairs may involve several characteristics, sometimes departing in different directions.In mixed-sex twins either sex can be more developed than its littermate but there is strong evidence for male dominance in size. This is apparent also in comparison of single fetuses of equal developmental stage.Comparison with fetal growth patterns of the mule deer (Odocoileus hemionus hemionus) and the white-tailed deer (Odocoileus virginianus) reveals that the subspecies of hemionus possess generally similar patterns. However, both races of this species differ from virginianus in a number of features of relative growth.Many structural changes occur at a smaller fetal size in columbianus than in hemionus or virginianus in keeping with the smaller adult size of the former. The heterogonic growth constants of columbianus and hemionus for five segments upon which comparison can be made are similar, but differ from those of the species virginianus. It appears, therefore, that patterns of relative growth are closely similar within the species even where there are considerable differences in mature size of the subspecies. Interspecies differences occur even where ultimate size and general proportions may be similar.
Ergasilus auritus Markewitsch, 1940 (Copepoda: Ergasilidae) from Gasterosteus aculeatus Linnaeus, 1758 in Newfoundland
Authors: Hanek George , Threlfall William
Published: April 2011

Ergasilus auritus Markewitsch, 1940 is recorded and figured from Gasterosteus aculeatus Linnaeus, 1758 in Newfoundland. This is the first record of the species from this province, and greatly extends the known range of the parasite.
The occurrence of brown adipose tissue in the adult red squirrel (Tamiasciurus hudsonicus)
Authors: Aleksiuk Michael
Published: April 2011

Brown adipose tissue is demonstrated to be present in adult red squirrels in the vicinity of Winnipeg, Canada. Electron microscopy revealed ultrastructure typical of this tissue in other species.
The effect of apparent predation risk on the respiratory behavior of the Florida gar (Lepisosteus platyrhincus)
Authors: Smith Roger S. , Kramer Donald L.
Published: April 2011

The interbreath interval for aerial and aquatic ventilation was determined for seven Florida gars (Lepisosteus platyrhincus, Pisces, Lepisosteidae) before, during, and after exposure to the simulated threat of predation by a mounted great blue heron (Ardea herodius, Aves, Ardeidae). During exposure to the heron, air-breath interval increased by 118% while water-breath interval decreased by 13% as compared with the pre-heron period. This provides evidence that ecological factors not directly involved in the physiology of gas exchange can influence respiratory partitioning in fishes. It also supports the hypothesis that retention of water-breathing capacity in air-breathing fish can reduce the risk of aerial predation in these species.
An ultrastructural study of spermatogenesis and the morphology of the testis in the nemertean worm Tetrastemma phyllospadicola (Nemertea, Hoplonemertea)
Authors: Stricker Stephen A. , Cavey Michael J.
Published: April 2011

Ripe male specimens of the nemertean worm Tetrastemma phyllospadicola (Nemertea, Hoplonemertea) measure about 7 mm long and characteristically possess 100–200 saccular testes. Each testis connects to a short gonoduct which is lined by myofilament-containing cells. The testicular sac is also lined by cells packed with myofilaments and typically contains scattered clusters of spermatogenic cells and bundles of sperm. During spermatogenesis, a spermatogonium divides mitotically several times and ultimately forms a cluster of primary spermatocytes that remain interconnected by narrow cellular bridges. Spermatocytes undergo meiotic divisions to produce syncytial clones of spermatids. As spermiogenesis proceeds, each spermatid differentiates into a modified spermatozoon with a wavy head measuring about 40 μm long. The head contains a well-developed acrosomal complex situated lateral to the anterior end of the nucleus and a long mitochondrion that lies within a groove in the posterior part of the nucleus. A discrete midpiece is lacking. The centriolar anchoring apparatus comprises nine unbranched spokes, and the tail exhibits a 9 × 2 + 2 arrangement of microtubules. Somatic cells that possess ramifying processes are intimately associated with the spermatogenic clones in each testis. Peculiar attributes of the testes and spermatozoa of this species are discussed with reference to previous accounts of spermatogenesis in nemerteans.
Multiple-foundress associations in a temperate population of Halictus ligatus (Hymenoptera; Halictidae)
Authors: Packer Laurence
Published: April 2011

Thirteen pleometrotic (multiple-foundress) nests of the primitively social sweat bee Halictus ligatus were excavated in the summer of 1984 at Victoria, near Toronto, southern Ontario. Subordinate foundresses were significantly smaller than both dominant females in pleometrotic nests and females that nested solitarily. Most subordinates were smaller than the workers that they helped to raise. These small females could have been surviving workers from the previous summer or the offspring of workers. It seems unlikely that they were malnourished reproductive brood individuals produced as a result of parental manipulation. In successful nests, the number of workers produced was positively correlated with the number of founding females such that productivity per foundress remained fairly constant. Pleometrotic nests also produced more reproductives than haplometrotic (single-foundress) ones. Subordinates may occasionally lay reproductive brood eggs. The increased productivity of multiple-foundress nests was not quite sufficient, by itself, to select for subordinate behaviour. The small subordinates had lower potential productivities in comparison to the larger females. This decreased reproductive potential, when combined with the increased productivity of pleometrotic nests, was sufficient to make subordinate behaviour selectively advantageous. When both factors are taken together, subordinate behaviour is selected for as long as the coefficient of relatedness between dominant and subordinate individuals is greater than 1/4. This indicates that high coefficients of relatedness are not necessary for pleometrosis to be selectively advantageous under the conditions found in this study. Dominant females may suffer increased reproductive competition from their numerous workers. This, plus the difficulty of ensuring association with siblings in spring, may be the reason why multiple-foundress associations were uncommon at this locality. The data presented here are compared with those from other studies of this species. The factors promoting pleometrosis in halictines are compared with those that result in multiple-foundress associations in temperate polistine wasps.
Asynchronous and synchronous hatching: effect on early growth and survivorship of Herring Gull, Larus argentatus, chicks
Authors: Hébert Percy N. , Barclay Robert M. R.
Published: April 2011

The adaptive significance of asynchronous hatching in the Herring Gull, Larus argentatus, was examined during the summer of 1984 at Kent Island, New Brunswick. Chick growth and behaviour in 28 experimental three-egg clutches in which the eggs hatched synchronously (i.e., hatch interval ≤ 24 h between the first (A chick) and last (C chick) hatched) were compared with that of 15 control three-egg nests with normal hatching asynchrony (A–C hatch interval > 24 h). All chicks had similar hatch weights, except for control C chicks, which on average were significantly lighter than their nest mates and experimental chicks. Growth rates were also similar for all chicks within and between groups, except for control C chicks, which grew at a significantly slower rate compared with nest mates and experimental chicks. In control broods, C chicks disappeared first significantly more often than A or B chicks. In experimental broods, a similar proportion of A, B, and C chicks disappeared first. Survivorship, through to day 5 posthatch, was significantly lower for control C chicks than for control A and B chicks as well as experimental chicks. These results suggest that the benefit Herring Gulls achieve hatching their eggs asynchronously results from the competitive advantage accrued to the A chick (and the B chick to some degree), which allows them to obtain more food, especially during periods of food stress. Subsequently the probability of survival of the older, more fit chick(s) is enhanced.
New species of Eylais (Acari: Hydrachnellae; Eylaidae) parasitic on water boatmen (Insecta: Hemiptera; Corixidae), and a key to North American larvae of the subgenus Syneylais
Authors: Smith Bruce P.
Published: April 2011

Larvae of six species of Eylais, including five new species, were found parasitizing water boatmen in central and western Canada. Eylais euryhalina n. sp., Eylais lancianii n. sp., Eylais wainsteini n. sp., and Eylais peutrilli n. sp. are all close relatives of the European Eylais infundibulifera Koenike, but their larvae can be separated from one another by size and by morphology of the dorsal, anal, and dorsolateral plates. Eylais deviata n.sp. appears to be most closely related to species of Eylais that parasitize aquatic beetles and probably is the result of a switch in host utilization. Eylais discreta Koenike shows considerable size variation within Canada and can be slightly larger than European specimens (based on published measurements), but there are no distinct groups based on size. While all the species of Eylais encountered are generalist parasites of Corixidae, there are apparent differences in host utilization.
Collembola of the Canadian high arctic. Review and additional records
Authors: Fjellberg Arne
Published: April 2011

A revised list of species from the Queen Elizabeth Islands is given, including new records from Ellesmere, Devon, Cornwallis, Bathurst, King Christian, and Ellef Ringnes islands. Fifty species are reported (43 named and 7 unnamed), with the highest number from Ellesmere Island (41). About 75% of the species in the area have a circumpolar or holarctic distribution.
Individual and group behaviour of pastured cattle in response to attack by biting flies
Authors: Ralley Wendy E. , Galloway Terry D. , Crow Gary H.
Published: April 2011

In 1983 and 1984 the impact of biting flies on the behaviour of pastured heifers was determined for two herds of cattle in eastern Manitoba. One herd received a whole-body spray of cypermethrin (0.1% active ingredient) per animal every 14 days and the other was an untreated control herd. Horse flies (predominantly Hybomitra spp.) were the most bothersome to the heifers, with peak numbers of flies mostly occurring between 11:00 and 15:00. Horse flies and mosquitoes (Aedes spp.) caused an increase in individual avoidance responses of the animals, including head tosses, foot stomps, ear flicks, and tail switches. In 1983, the numbers of tail switches and foot stomps were significantly higher in the control herd, and in 1984, the numbers of head tosses were significantly higher in the treated herd. The formation of grazing lines and bunching were the most prevalent herd responses to biting fly attack. Stampeding was observed only under the most extreme mosquito pressure. Using canonical discriminant analysis on behaviour data, significant differences were identified in behaviour before and after July 10, 1984. Similarly, animals treated with cypermethrin displayed significantly fewer behavioural responses to biting fly attack than nontreated animals.
Coda communication by sperm whales (Physeter macrocephalus) off the Galápagos Islands
Authors: Weilgart Linda , Whitehead Hal
Published: April 2011

To gain insight into the function of sperm whale vocalizations known as codas (short, patterned series of clicks), sperm whales (Physeter macrocephalus) were tracked continuously for periods of days totalling months off the Galápagos Islands, Ecuador, and vocalizations were tape recorded systematically. In total, 1333 codas were classified according to their temporal pattern and the number of clicks they contained. Codas were found to be temporally very clustered, and could be categorized into 23 fairly discrete types. Sequential analysis of codas revealed that they overlapped one another according to type in a nonrandom way, and that type 5 tended to initiate coda exchanges. "Regular" coda types (with evenly spaced clicks) tended to occur with other regular coda types and "irregular" coda types (with one or two delayed final clicks) were heard with other irregular coda types. Codas may function principally as a means of communication, to maintain social cohesion within stable groups of females following periods of dispersion during foraging.
Asymmetrical gait of the Saharian rodent Meriones shawi shawi (Duvernoy, 1842) (Rodentia, Mammalia): a high-speed cineradiographic analysis
Authors: Gasc Jean-Pierre
Published: April 2011

The fast gait of jirds (Meriones shawi shawi) was analyzed by means of high-speed X-ray cinematographic film (500 frames/s). The gait is asymmetrical, related to the transverse gallop with a cycle duration of 0.15 s, for a speed of 1 m∙s−1. The flight phase, which can last for up to 10% of the cycle duration, follows the takeoff of one anterior limb. The kinematics of the hind limb reveal that the angular excursion of the femur is small, but is increased 100% by dorsiflexion (stance phase) and ventroflexion (swing phase) of the vertebral column. During the propulsive moment, the knee joint is stable while the ankle joint opens quickly to a wide angle (70° in 40 ms). The shank joint and the head oscillate vertically, and the relative movements of the anterior and posterior parts of the body create dynamic effects facilitating the cantilevered position of the forequarters during 35% of the cycle. This kinematic analysis reveals that these small mammals differ from large ones in the way they use the geometry of their limbs even when the limbs are moved in a parasagittal plane during fast running.
Morphology of the compound eyes as an indicator of life-style in carabid beetles
Authors: Bauer Thomas , Kredler Mechthild
Published: April 2011

Twelve diurnal, 9 nocturnal, and 6 intermediate species of carabid beetles common in central Europe were investigated with respect to hunting behaviour and the morphology of the head and eyes. Diurnal visual hunters are characterized by typical visually guided predatory behaviour, which consists of a turn toward the prey, followed by a jerky approach and a lunge. Nocturnal species do not react to visual stimuli but use exclusively chemical or tactile cues for orientation. Visual hunters have broader heads than the other two groups (≈ 26% of the body length as opposed to ≈ 20%), shorter antennae (≈ 45% of the body length compared with ≈ 52% in the other two groups), ≈ 50% larger eye surfaces, and, correspondingly, 50% more ommatidia per eye. The binocular overlap of the frontal visual fields of both eyes is more than 50° in visual hunters; in nocturnal and intermediate species it is usually less than 40°. Nearly all species have acute zones with small interommatidial angles in the frontolateral parts of the eye, but in visual hunters these are much more distinct. As a readily measurable indicator of the hunting behaviour and life-style of a species we describe an eye–antenna angle that is more than 60° in typical visual hunters and, in most cases, much less than 55° in nocturnal species.
Masculinized females in a population of Leptodiaptomus minutus (Copepoda, Calanoida)
Authors: Sillett Kristine B , Stemberger Richard S
Published: April 2011

In a population of the common freshwater copepod Leptodiaptomus minutus Lilljeborg, 7.3% of adult females exhibited male secondary sexual characteristics. Although these masculinized or intersex females had the internal morphology of normal females, they possessed one or rarely two normal geniculate male antennules, and in a few instances male fifth legs. The sex ratio of normal adult males to females in the population was 1:1. No differences in body size among normal males, normal females, and masculinized females were found. Antennule lengths of males and masculinized females were not significantly different from one another; however, normal females had longer antennules than either males or masculinized females. Mating experiments indicated that masculinized females were functionally female and they were able to mate with normal males to produce offspring that were normal or masculinized. The occurrence of intersex copepods in lakes of North America may be more widespread than we now recognize because they can be easily overlooked or mistaken for normal adults.
The effects of habitat fragmentation by forestry and agriculture on the abundance of small mammals in the southern boreal mixedwood forest
Authors: Bayne Erin M , Hobson Keith A
Published: April 2011

To determine the effects of forest fragmentation on the abundance of small mammals, we livetrapped at edges and in the interior of forest patches in contiguous, logged, and agricultural landscapes in the southern boreal mixedwood forest of Saskatchewan. From 1994 to 1996, we captured 1548 small mammals (11 species) during 8172 trap-nights. The abundance of all small mammals combined was lower in forest patches isolated by logging than in contiguous forest or farm woodlots surrounded by agricultural land. This pattern was consistent in all years, despite significant annual fluctuations in numbers of the boreal red-backed vole (Clethrionomys gapperi), one of the most abundant species in our study area. Red squirrels (Tamiasciurus hudsonicus) and northern flying squirrels (Glaucomys sabrinus) were more abundant in farm woodlots. The abundance of deer mice (Peromyscus maniculatus) was significantly lower in forest patches surrounded by clearcuts, and we speculate that they may have used clearcuts more than forest patches. In contrast, the numbers of boreal red-backed voles were similar among landscapes. The only species showing a response to edge was the deer mouse, which was significantly more abundant at edges of farm woodlots than in interiors. We also found no significant difference in abundance of any species between small (10 ha) and large (>>20 ha) farm woodlots. For most species, within-landscape attributes such as edge and patch size seemed to have little effect on their abundance. However, for a variety of reasons, small-mammal numbers seem to vary considerably among forest patches in different landscapes.
Compensatory behavior of Ensatina eschscholtzii in biological corridors: a field experiment
Authors: Rosenberg Daniel K , Noon Barry R , Megahan John W , Meslow E Charles
Published: April 2011

Despite the general lack of theoretical or empirical support, biological corridors are assumed to mitigate the detrimental effects of habitat fragmentation by increasing landscape connectivity. To test the hypothesis that mechanisms which affect immigration rates from a source to a target patch are affected by the presence of a corridor in an otherwise unsuitable matrix, we created two strongly contrasting pathways in replicated field experiments. One pathway type included only bare mineral soil, the other included a potential corridor. We conducted these experiments with Ensatina eschscholtzii, a salamander in the family Plethodontidae. Pathways with surface organic material removed provided a harsh environment for E. eschscholtzii, which was reflected by lower selection, shorter residency time, and higher movement rates than on pathways that contained vegetation (corridor pathways). However, the numbers of E. eschscholtzii reaching target patches connected by corridor pathways were greater than those reaching target patches connected by bare pathways only in plots in which the matrix environment seemed most severe. Our results suggest that identifying candidate corridor areas on conservation maps might be difficult because animals may show compensatory behavioral responses to different types of habitat separating source and target patches. We argue that knowledge of a species' habitat-specific dispersal behaviors is critical to reliably designating corridors as functional components of reserve design.
Grizzly bear feeding activity at alpine army cutworm moth aggregation sites in northwest Montana
Authors: White, Jr. Don , Kendall Katherine C , Picton Harold D
Published: April 2011

Grizzly bears (Ursus arctos horribilis) consume army cutworm moths (Euxoa auxiliaris) from late June through mid-September at alpine moth aggregation sites in Glacier National Park, Montana. To better understand the importance of army cutworm moths to grizzly bears, we determined the sex and age classes and minimum numbers of grizzly bears foraging at known alpine moth aggregation sites, and documented the timing and use patterns of grizzly bears foraging in these areas. A minimum of 36 grizzly bears were observed 106 times feeding at 6 of 9 known moth aggregation sites from late June through mid-September in 1992-1995; no bears were observed on moth sites in 1993. Bears fed on moth aggregations disproportionately more at elevations >2561 m, on slopes between 31° and 45°, and on southwest-facing aspects. Lone adult grizzly bears appeared to be underrepresented and subadults overrepresented at moth sites. Moths are highly digestible; all parts are digested except for the exoskeleton. We propose that army cutworm moths are an important, high-quality, preferred summer and early-fall food for grizzly bears in Glacier National Park. We do not present any data that demonstrate an increase in the importance of moths when other foods fail.
Fibre types in breast and leg muscles of hand-reared and wild grey partridge (Perdix perdix)
Authors: Pyörnilä Ahti EI , Putaala Ahti P , Hissa Raimo K
Published: April 2011

Fibre types and sizes and their relative numbers and cross-sectional areas in M. pectoralis, M. supracoracoideus, and M. iliotibialis of hand-reared and wild grey partridge (Perdix perdix) were determined in order to see if there are differences that could account for the poor survival of hand-reared birds released into the wild. Histochemical staining for myosin ATPase and succinate dehydrogenase (SDH) showed that most breast-muscle fibres (80-90%) are of the fast-twitch glycolytic (FG) type and a smaller portion of the fast-twitch oxidative glycolytic (FOG) type. In M. iliotibialis, about 60% of the fibres were FG fibres and the rest were of the FOG type. Judging from the low intensity of SDH staining, FOG fibres in the grey partridge appear weakly oxidative only. The relative number of FG fibres and their relative cross-sectional area in M. pectoralis were larger in the hand-reared than in the wild birds. The cross-sectional areas of both fibre types in M. iliotibialis were significantly larger in the hand-reared birds. Taken as a whole, these findings alone do not account for the poor survival of hand-reared partridge in the wild.
Phenology and life-cycle regulation of the fishing spider Dolomedes triton Walckenaer (Araneae, Pisauridae) in central Alberta
Authors: Zimmermann Manfred , Spence John R
Published: April 2011

Dolomedes triton Walckenaer, a widespread and common fishing spider in North America, has a semivoltine life cycle in central Alberta, Canada. Juvenile spiders hibernate twice. According to evidence from laboratory rearings and patterns in field collections, the main overwintering stages are instars 3-5 and 9-11. After the second overwintering period, large juveniles moult once or twice to reach the reproductive adult stage. Juveniles grow rapidly between May and August but during overwintering between September and April, virtually no growth (measured as maximum carapace width of individuals) was observed in field populations. Dolomedes triton has a variable number of juvenile stages, ranging from 10 to 15 in males and from 9 to 15 in females. Both overwintering phases are facultative even though most individuals overwinter twice in central Alberta: at high temperatures (24-25°C) and under long-day conditions (either 18 h light : 6 h dark or 19 h light : 5 h dark) juveniles can develop directly to adults. Short-day photoperiods did not prolong stage durations, but warm periods, when experienced late in development only, were associated with extra moults, and may thus delay maturation until the following spring. Although the second overwintering period is a quiescence regulated strictly by temperature, regulation of the first overwintering period is more complex, including probable preconditioning through interaction of temperature and photoperiod.
The role of chemoreception in salmon-egg predation by coastrange (Cottus aleuticus) and slimy (C. cognatus) sculpins in Iliamna Lake, Alaska
Authors: Dittman Andrew H , Brown Gayle S , Foote Chris J
Published: April 2011

Egg predation by coastrange sculpins (Cottus aleuticus) and slimy sculpins (C. cognatus) may be a major factor affecting sockeye salmon (Oncorhynchus nerka) production in Iliamna Lake, Alaska. In this study, we examined the potential roles of visual and chemosensory cues in egg predation by sculpins. A field study tested whether sculpins were differentially attracted to minnow traps baited with eggs that were (i) visible with no odours present, (ii) visible with odours present, or (iii) not visible with odours present. Our results indicated that sculpins do not require visual cues for detecting salmon eggs. However, attraction to sockeye eggs did require chemical cues emanating from the eggs. To characterize the chemical attractants that emanate from salmon eggs, we tested whether sculpins were attracted to test odours in a two-choice maze. Test odours were prepared by soaking eggs in lake water. Sculpins preferred egg wash to lake water but demonstrated no attraction to ovarian fluid versus lake water, suggesting that the attractive substances are derived directly from egg material. These results are discussed in relation to the known sensory mechanisms involved in feeding by sculpins as well as to the ecological relationship between spawning sockeye salmon and sculpins.
Morphology and ultrastructure of sensilla on the proboscis of the adult spruce budworm, Choristoneura fumiferana (Clem.) (Lepidoptera: Tortricidae)
Authors: Walters B D , Albert P J , Zacharuk R Y
Published: April 2011

Styloconic and basiconic sensilla are the only types of chemosensilla located on the proboscis of the adult spruce budworm, Choristoneura fumiferana. The styloconic sensilla (Ss's) are arranged on each galea in two rows, an inner and an outer one, each with about 35 sensilla. Basiconic sensilla (Sb's) are interspersed in an irregular row between the Ss's of the inner row. They are also found in the proximal part of the food channel. Each Ss consists of a single sensory peg inserted at the top of a style bearing 6-9 ridges that extend from the base of the style to the sensory peg socket, at which point the ridges protrude to form sharp points. The peg has a terminal pore about 0.08 µm in diameter, which is permeable to cobalt ions and contains a sievelike structure. The sensillum houses four dendrites; the ultrastructure of three is consistent with a chemosensory function and that of one is consistent with a mechanosensory function. Each Sb has a peg inserted in a socket directly on the surface of the proboscis. Its terminal pore has a diameter, sieve-like contents, and permeability to cobalt ions similar to those of the Ss peg. There are 4 or 5 innervating neurons; the dendrite of one is structurally typical of a mechanosensory neuron and the remainder are typical of a chemosensory neuron. Both types of sensilla show an ultrastructure consistent with a bimodal chemo-mechanosensory function.
Diving behaviour of Antarctic fur seal (Arctocephalus gazella) pups
Authors: McCafferty D J , Boyd I L , Taylor R I
Published: April 2011

The diving behaviour of Antarctic fur seal (Arctocephalus gazella) pups on Bird Island, South Georgia (54°S, 38°W), was examined during February-April 1996 using capillary-tube depth gauges (CDGs) and time-depth recorders (TDRs). CDGs were deployed on 6 female and 10 male pups aged 65-101 days. Depths measured by CDGs were within 10% of maximum depths recorded by TDRs. Maximum dive depths averaged 13.8 m and ranged from 4.2 to 28.1 m. Body length alone accounted for 66% of the total variation in maximum dive depth. TDRs were deployed on one female and two male pups aged 89-101 days. In total, 4858 dives were recorded during 173 h at sea. The average dive depth and duration was 4.2 m and 20 s, respectively. Pups made a total of 34 trips and each spent 50% of its time at sea. Not all trips included dives; however, when diving took place trips lasted, on average, 6.8 h and contained 214 dives, most of which took place during daylight. Dives were made at a frequency of 30/h and the vertical distance dived was 124 m · h-1. The number of dives, percentage of time spent submerged, percentage of time spent diving, dive frequency, and dive rate were positively correlated with trip duration. These results show that Antarctic fur seal pups develop diving skills at an early age, and by the time they are close to being weaned they have the diving ability to exploit prey similar to those taken by adults.
The effect of ice conditions in northern Hudson Bay on breeding by Thick-billed Murres (Uria lomvia)
Authors: Gaston Anthony J , Hipfner Mark
Published: April 2011

We compared annual indices of breeding by Thick-billed Murres, Uria lomvia, at a colony in northern Hudson Bay with annual variation in the extent of sea-ice cover during May and June, the period when birds arrive and initiate breeding. Greater ice cover was associated with delayed breeding and lower attendance rates at the colony during the early incubation period (late June). We detected no effect on egg size, reproductive success, or adult body mass. The extent of ice cover in May was positively correlated with the proportion of Arctic cod fed to nestlings, and in June with the proportion of capelin in the rest of the diet. There was a positive correlation between the proportion of capelin in the chick diet and chick body mass at 14 days of age. We attribute the delay in laying during years of heavy ice cover to the reduced area available for foraging close to the colony. Prolonged persistence of ice, though delaying the onset of laying, may benefit the birds later in the season, as they forage preferentially in the vicinity of ice. We suggest that the strong relationships we observed between the extent of ice cover and aspects of the breeding biology of Thick-billed Murres may apply to other Arctic-nesting seabirds and may reflect conditions affecting the entire marine food web.
The foraging ecology of the gray rat snake (Elaphe obsoleta spiloides). III. Searching for different prey types in structurally varied habitats
Authors: Mullin Stephen J , Cooper Robert J , Gutzke William HN
Published: April 2011

Dietary generalists foraging for prey inhabiting different microhabitats may encounter different levels of structural complexity. We examined the effect of variation in prey type on the predation success and behaviors of the semi-arboreal gray rat snake (Elaphe obsoleta spiloides) foraging in structurally varied habitats. Individual snakes searched for contents of arboreal birds' nests or for small rodents in enclosures that simulated a bottomland hardwood forest habitat with one of five levels of vegetation density. Latency to prey capture was lower when the snakes were searching for small rodents than when they were searching for birds' nests, and lower for male snakes than for females. Generally, snakes were most successful when searching for prey in enclosures with low levels of structural complexity, and experienced decreased predation success in barren or highly complex habitats. Habitats with low levels of structural complexity may offer the snakes concealment from predation while not obscuring their perception or pursuit of prey. Of behavior durations measured in the trials, over 95% concerned 6 of the 20 behaviors described, and 3 of these occurred more often than the others, regardless of variation in the structural complexity of the habitat. Foraging gray rat snakes exhibited behaviors characteristic of active and ambush foraging strategies that increased their predation success on different prey types in the varied environments.
Soil temperature, rock selection, and the thermal ecology of the amphisbaenian reptile Blanus cinereus
Authors: López Pilar , Salvador Alfredo , Martín José
Published: April 2011

We studied the thermal ecology of the amphisbaenian reptile Blanus cinereus in central Spain, focusing on the relationship between the available underground thermal environment and the thermal biology of B. cinereus. We specifically examined which soil microhabitats might be used by amphisbaenians, given thermal preferences measured in the laboratory, in relation to daily substrate-temperature cycles. We also examined whether actual rock use is related to thermoregulatory behaviour. Soil-temperature cycles suggest that behavioural selection of low temperatures enables B. cinereus to maximize its activity period and activity area within its preferred body-temperature range. An amphisbaenian moving between the surface and 10 cm depth in sun-exposed soil could maintain its body temperature within the preferred range for 8 consecutive hours. Amphisbaenians selected rocks of intermediate thickness (10-20 cm) as temporary heating stations, but used rocks of different thicknesses at different times of day. In spring, during daylight hours B. cinereus can attain preferred body temperatures in superficial soil layers and maintain them for long periods, presumably at low cost, allowing them to forage where food is most abundant.
Burst swimming and its enzymatic correlates in the threespine stickleback (Gasterosteus aculeatus): full-sib heritabilities
Authors: Garenc Christophe , Silversides Frederick G , Guderley Helga
Published: April 2011

Full-sib heritabilities of burst-swimming capacity and its enzymatic correlates were calculated in juvenile threespine sticklebacks, Gasterosteus aculeatus, from 25 families raised under constant laboratory conditions. Variation among families in burst-swimming performance, enzyme activities, body size, and condition of the juveniles was considerable. Estimates of full-sib heritabilities of absolute and relative burst-swimming performance decreased during ontogenesis, as they were higher for 2-month-old than for 3.6-month-old sticklebacks. This decline may reflect a decrease in the importance of paternal effects with age, as well as an increase in intrafamilial variability due to the existence of feeding or social hierarachies. Enzymatic correlates of burst-swimming performance measured in 3.6-month-old sticklebacks had higher full-sib heritabilities than burst-swimming performance itself, with the highest values found for cytochrome c oxidase, followed by lactate dehydrogenase and then phosphofructokinase and creatine phosphokinase. These results suggest that genetic factors may have a considerable influence upon burst-swimming performance and muscle metabolic capacities of juvenile threespine sticklebacks, but that this influence may be tempered by biotic interactions.