bluuebunny/crossref_metadata_2025 huggingface dataset:
Spine deficiency and polymorphism in a population of Gasterosteus aculeatus: an adaptation to predators?
Authors: Reimchen T. E.
Published: December 2009

A population of Gasterosteus aculeatus from a muskeg lake on the Queen Charlotte Islands shows a spine polymorphism, with 80% lacking the second dorsal spine and 68% lacking the pelvic spines. Females were more prevalent among phenotypes with greater spine number, and males were more common among those with fewer spines. Adult females, as well as juveniles of both sexes with pelvic spines, were more frequent in the limnetic habitat, whereas adult males and juveniles without pelvic spines were common in the littoral region.Five species of piscivorous birds, each in low numbers, foraged in the lake. Extensive predation in the limnetic region by Gavia immer and, secondarily, Podiceps spp. is implicated as a selective pressure favouring the greater spined phenotype.Odonate Nymphs (Aeshna spp.) consumed juvenile fish in predation experiments and in the lake proper. Nymphs were common in the littoral zone, where submerged debris provided substrate for foraging. It is proposed that spine loss in this population of G. aculeatus is an adaptation to the hunting technique of Aeshna, whereby reduced external structures such as spines minimize frictional contact for a grappling predator. Experimental data and other gasterosteid populations are discussed with reference to these proposals.
Predation upon pelvic phenotypes of brook stickleback, Culaea inconstans, by selected invertebrates
Authors: Reist James D.
Published: December 2009

Laboratory experiments investigated selective predation by aquatic insects upon phenotypes of brook stickleback (Culaea inconstans), with and without pelvises, from Wakomao Lake, Alberta, Canada. Predation by Lethocerus americanus (water bug) and nymphs of Aeschna spp. (dragonflies) was random upon each phenotype. Predation by the larvae of Dytiscus spp. (water beetle) resulted in significant selection for with individuals possessing five dorsal spines. The observed selection was at least partially due to closer approaches to the predator made by the withs. No selection occurred for either phenotype with six dorsal spines. This evidence supports an hypothesis that the pelvic variation is maintained by differential predation.
The pathology of "saddleback" disease of underyearling Atlantic salmon (Salmo salar)
Authors: Cone D. K. , Miller J. D. , Austin W. K.
Published: December 2009

This study describes the pathology of "saddleback" disease of underyearling Atlantic salmon (Salmo salar) cultured at the Mactaquac Fish Hatchery near Fredericton, New Brunswick. A gram-negative, flexible, bacterium had a constant association with the characteristic lesion. It is thought that the bacteria enter the dorsal fin and then spread into the surrounding dermis by moving through the connective tissue and collagen layers. This causes sloughing of the overlying epidermis and some scales, and results in a symmetrical band of discoloration on the flanks of the body on either side of the dorsal fin. Invasion of the underlying epimysium and perimysium leads the bacteria deep into the dorsal fin levators and the epaxial muscles on either side of the dorsal fin. Evidence suggests the bacteria can enter muscle cells and destroy the cell from within. The bacterium was not found in any other tissue.
On Heterocypris makua (Tressler) 1937, a freshwater ostracod (Crustacea: Ostracoda) from the Hawaiian Islands, with notes on the other species of the genus
Authors: Victor Reginald , Fernando C. H.
Published: December 2009

Heterocypris makua (Tressler) 1937, originally represented by a single holotype female, has been rediscovered at two different localities in Hawaii, Hawaiian Islands. Both the type and additional material are used to redescribe this species and a detailed comparison is given.
Food and indicators of food availability for common terns on the lower Great Lakes
Authors: Courtney Peter A. , Blokpoel Hans
Published: December 2009

The food of common terns (Sterna hirundo) nesting on the lower Great Lakes was studied in 1979. In western Lake Ontario 90% of the diet comprised alewife and smelt. In the Niagara River the principal food items were smelt, emerald shiner, common shiner, and bluntnose minnow and in eastern Lake Erie the principal items were smelt, emerald shiner, and trout-perch. Nonfish material was rarely observed. Methods for studying the diets of common terns on the Great Lakes are examined.Three indicators of food availability were examined in 1979 at the Eastern Headland in western Lake Ontario: (1) percentage fish accepted by chicks, (2) foraging time, and (3) chick growth. More food was presented to the chicks than they could eat. Food acceptance levels increased with chick age and brood size and ranged from 43.5 to 91.5%. Foraging trip times were 17.2 min on average and, depending on brood size, tern pairs spent an estimated 45–64% of daylight hours foraging for food for their chicks. Weights of 15-day-old chicks in three-chick broods were higher than those reported for other parts of the breeding range.
Variation of the first head annule in Canadian populations of Pratylenchus penetrans (Nematoda: Pratylenchidae) from three host plants
Authors: Anderson R. V. , Townshend J. L.
Published: December 2009

Configuration of the surface of the first head annule in 80 females of Pratylenchus penetrans from cherry, strawberry, and tobacco in Canada were compared to assess its diagnostic value in species identification. Most significant were structural features of the oral plate, defined collectively as the oral disk, and its dorsal and ventral extensions. The oral plate varied, often markedly, in surface configurations that were representative of different species groups. Of these, the most distinctive were hexaradiate and dumbbell in shape, comprising, respectively, 25 and 35% of the total heads scanned by scanning electron microscope. In one female the oral plate was panduriform, representing another species group, whereas the rest were of iniergrading forms of a hexaradiate symmetry. The relative proportions of these forms in a given population varied with the host, suggesting an external or selective influence. Of those in 25 females from strawberry 25% were hexaradiate, and of 27 from cherry 52% were dumbbell shaped. Also variable, but to a lesser extent, were the size, shape, and position of the amphid apertures. It is concluded that similar studies under more variable conditions may further extend the diversity of forms.
Fat levels in a subarctic population of Peromyscus maniculatus
Authors: Gyug Les W. , Millar John S.
Published: December 2009

Fat content (FAT), lean dry weight (LDW), and caloric content (KCAL) were examined in a natural subarctic population of Peromyscus maniculatus. FAT was not significantly correlated with size (LDW) of the animal. FAT of adult males was negatively correlated with minimum ambient temperatures and was not correlated with reproductive condition. LDW of adult males did not vary in relation to season. FAT of prebreeding adult females was high and decreased in response to breeding, but LDW increased in response to breeding so that KCAL remained constant. KCAL was low in adult females only after the breeding season. Mice dying in live traps had significantly lower FAT than did any other group of adults indicating that wild mice do not normally deplete their fat reserves. KCAL of postweaning young increased with age due to an increase in LDW but not in FAT. We suggest that fat levels are intrinsically controlled in wild Peromyscus according to the probability of having to make extraordinary energy expenditures and are not simply subject to extrinsic controls through the balance of food availability and energy demands.
Removal and replacement of male blue grouse on persistent and transient territorial sites
Authors: Lewis R. A. , Zwickel F. C.
Published: December 2009

In the springs of 1978 and 1979 we removed all male blue grouse (Dendragapus obscurus), both original occupants and subsequent replacements, from a series of persistent and transient territorial sites (those used regularly and intermittently, respectively). In both years more replacements settled on persistent than on transient sites. Most replacement males were adults, most of which likely would not have taken territories had we not made these sites available. The presence of nonterritorial adults, reported here for the first time, suggests that territorial behaviour limits breeding densities of male blue grouse. Testes of replacement adults, although smaller than those of resident males collected at comparable times, all contained mature sperm. Yearling males are seldom territorial; but of eight that took territories on removal sites all except one selected persistent sites.
Cephalic sense organs and body pores of Xiphinema americanum (Nematoda: Dorylaimoidea)
Authors: Wright K. A. , Carter R.
Published: December 2009

The fine structure of the cephalic sense organs and body pores of the plant parasitic nematode Xiphinema americanum is described by transmission electron microscopy. All of the six inner labial, six outer labial, and four cephalic sense organs as well as the amphids have characteristics indicating chemosensitivity, but there are no clearly identifiable mechanosensitive units. Two pairs of simple internal sense organs, not associated with cuticle, also occur. Sensory dendrites all bear cilium-derived dendritic processes that contain axonemal doublets of microtubules. These doublets show radial and circumferential linkages characteristic of the ciliary necklace region of a cilium, although only an amorphous microtubule organizing center occurs in the usual place of a basal body.Both socket cell and sheath cell processes are associated with the cuticular sense organs. The cell body of the amphidial sheath cell is located well anterior to the central nervous system, before the level of the buccal dilator muscles.Body pores are associated with sensory units characteristic of chemosensitive organs. Hypodermal cells serve as their socket cells, whereas a separate sheath cell occurs in the body wall close to each pore.
Adrenal growth during pregnancy in the bank vole, Clethrionomys glareolus: initiation by mating
Authors: Gustafsson Torgny O. , Andersson C. Bertil
Published: December 2009

The relative roles of mating and the ovary in the initiating of adrenal growth in pregnant bank voles, Clethrionomys glareolus, were studied. In one experiment females were ovariectomized shortly after mating; 4 days later they had significantly heavier adrenals than unmated, ovariectomized controls. In another experiment females were ovariectomized and brought into oestrus by oestradiol- 17β injections. Half of the females were mated and after 4 days their adrenals were significantly larger than those of unmated controls. We conclude that the increase in adrenal weight during pregnancy in bank voles is triggered directly by mating, without involvement of ovarian hormones. The mechanism is suggested to be a neuroendocrine reflex, acting via the hypothalamus and the pituitary. The mechanism may be the same as that involved in the induced ovulation in this species.
Strike tactics of Esox
Authors: Webb P. W. , Skadsen J. M.
Published: December 2009

Strike tactics of a lunging piscivore attacking solitary prey were observed in an arena 50 cm long, 50 cm wide, and 10 cm deep and recorded on television video tape. The predators were cultured tiger musky (Esox sp.). The prey were fathead minnow (Pimephales promelas). Predator strikes were S type fast starts allowing multidirectional attacks. Two strike patterns were observed. Pattern A strikes commenced from a stretched-straight body posture and progressed from fast start stage 1 through the normal three-stage sequence. Pattern B strikes deleted the less efficient first stage, starting acceleration from an S posture. Strikes were directed in the vicinity of the center of mass of the prey, the point that moves least during escape attempts. Prey were usually attacked from the side, minimizing the displacement of the prey from the strike path after an escape attempt. Pattern A strikes were launched over distances from 3.8 to 33.9 cm and took 50–300 ms. Catch success was 42%. Pattern B strikes were used for short distances from 1.7 to 7.7 cm, taking 17–100 ms and were 95% successful. The observed strike tactics were those expected to maximize the probability of catching elusive fish prey.
A new species of Leuckartiara (Pandeidae, Hydrozoa) from the east coast of Vancouver Island
Authors: Arai Mary Needler , Brinckmann-Voss Anita
Published: December 2009

A new species of Leuckartiara, Leuckartiara foersteri n.sp., is described and illustrated. It is differentiated from all other species of the genus by marginal tentacles without abaxial spurs, and gonads with parallel folds, situated on adradial sides of cross-shaped manubrium with no distinct interradial connection.
Morphometric variation between populations of the balsam woolly aphid, Adelges piceae (Ratzeburg) (Homoptera: Adelgidae), in North America
Authors: Foottit R. G. , Mackauer M.
Published: December 2009

Morphological variation in characters of the first-instar and the adult stage of the balsam woolly aphid, Adelges piceae (Ratzeburg) (Homoptera: Adelgidae), were studied. Multiple discriminant analysis and UPGMA cluster analysis of the Mahalanobis generalized distances were used to classify 18 population samples collected on five Abies species throughout the known area of distribution. The populations were separated into three distinct groups: a "Maritime" group, a "British Columbia" group, and an "intermediate" group which consisted of samples from North Carolina, Oregon, and Washington. Variables taken from the adult morph gave a more consistent and, hence, a more reliable classification than the first-instar variables. Allocation of individual specimens into the three groups, as determined by identification functions, showed that the morphological characters measured in the adult stage correctly identified 85% of the specimens.It is suggested that the observed morphological divergence between eastern and western populations of A. piceae reflects the aphid's colonization history in North America. The importance of these findings for control is noted.
Phosphate transport by locust rectum in vitro
Authors: Andrusiak E. W. , Phillips J. E. , Speight J.
Published: December 2009

The rectal cuticle is permeable to H2PO4−, but much less so to HPO42−. Everted rectal sacs of Schistocerca gregaria transport PO4 from lumen to hemocoel side against large concentration and electrical differences. This active process is not caused by solvent drag and it obeys Michaelis–Menten kinetics. Entry of 32PO4 into rectal tissue from the lumen is inhibited by arsenate. Much of the 32PO4 is converted to organic forms in the tissue but these do not enter the hemocoel compartment. Net rates of PO4 movement across the rectal wall in vitro are high enough to explain recovery of phosphate secreted in situ by Malpighian tubules of starved locusts. The location and possible mechanism of PO4 transport are discussed.
Urine production in the shore crab, Hemigrapsus nudus
Authors: Dehnel Paul A. , Malley D. F.
Published: December 2009

Urine production was determined for the crab, Hemigrapsus nudus from an estuarine habitat with a seasonal pattern of high salinity – low temperature in winter and low salinity – high temperature in summer. Urine production was measured in crabs collected during winter and summer and held in two salinities, 25 and 75% seawater. Methods used were (1) blockage of nephropores with the physiological adhesive, methyl 2-cyanoacrylate monomer, and measurement of subsequent weight increase, and (2) rate of inulin excretion over four time periods: 6, 12, 18, and 24 h. Blockage and inulin excretion gave urine production rates of 15 to 17% body weight day−1 in 25% seawater. In 75% seawater urine production was estimated by blockage to be 6% body weight day−1 and by inulin excretion to be 12% body weight day−1. Summer crabs in 25% seawater produced urine at a slightly lower rate than did winter crabs. In 75% seawater, no seasonal difference was apparent. Urine production was independent of wet weight of crab. It is suggested that the lower rate of urine production by summer crabs in 25% seawater compared with winter crabs in that salinity is related to their lower haemolymph – seawater osmotic gradient and is an adaptation to lowered summer salinity.
Description and relationships of a new root-knot nematode, Meloidogyne sewelli n.sp. (Nematoda: Meloidogynidae) from Canada and a new host record for the genus
Authors: Mulvey R. H. , Anderson R. V.
Published: December 2009

A new root-knot nematode from Quebec, Canada, Meloidogyne sewelli n.sp. is described and illustrated from spike-rush, Eleocharis acicularis (L.) R &S. The most distinctive characters of the infective larva are its body length of 505–553 μm, posterior position of the dorsal esophageal gland orifice at 7–8 μm, and the presence of an inflated rectum. The egg sac is larger than the female and always contained within the root gall. Perineal pattern of the female is weakly etched or indistinct and the terminus of the male tail is distinctively subdigitate. The above type host plant is a new host record for root-knot nematodes. Relationships of the new species to five of the most closely related species are discussed and a taxonomic key and table of diagnostic characters to their infective larvae are presented.
The reproductive rates of yearling and older Ipswich Sparrows, Passerculus sandwichensis princeps
Authors: Ross Howard A.
Published: December 2009

The mean reproductive rates (number of 7-day-old nestlings raised per year per individual) of yearling and older Ipswich Sparrows breeding on Sable Is., Nova Scotia in 1977 and 1978 were the following: yearling males 3.3, older males 4.2, yearling females 3.9, and older females 4.7. The mates of older males began nesting earlier, laid larger clutches, and renested more quickly after each brood than did the mates of yearling males, thereby laying slightly more clutches and significantly more eggs. Older females laid slightly more and slightly larger clutches than did yearling females, resulting in a significantly greater production of eggs. The number of nestlings aged 7 days (i.e., the age immediately before nest leaving) raised per egg laid varied only slightly with parental age. Consequently, the reproductive rate increased with age because parental abilities must have increased by the same proportion as did the production of eggs.
Field fecundity of the spruce budworm (Lepidoptera: Tortricidae) as determined from regression relationships between egg complement, fore wing length, and body weight
Authors: Thomas A. W. , Borland S. A. , Greenbank D. O.
Published: December 2009

The assumption that the number of eggs laid by a spruce budworm moth in the field is the same as the number laid under laboratory conditions is shown to be false. A method is described for estimating what proportion of the potential fecundity obtained in the laboratory is actually laid in the field. The proportion was shown to range from 0 to 1 for individual females, but averaged between 0.70 and 0.86 for a given population at one locality. Results of this investigation have implications in population dynamics studies of the spruce budworm.
Diurnal rhythms of sodium transport in the freshwater mussel
Authors: Graves Sidney Yeider , Dietz Thomas H.
Published: December 2009

Sodium and chloride concentrations in the blood of pondwater acclimated Carunculina texasensis on a 12 h light (L): 12 h dark (D) photoperiod, undergo daily oscillations of 1 to 2 mmol/L. Changes in the active transport rate of Na are responsible for the changes in the blood sodium levels over the 24-h period. During the photophase, the blood level of Na and Cl is at a nadir and the clams are losing Na (net flux (Jn) = −0.36 μ mol/g dry tissue∙h−1) due to a depressed Na influx (Ji = 0.30 μ mol/g dry tissue∙h−1). The opposite response is observed during the scotophase; the blood concentration is significantly increased and the mussels are gaining sodium (Jn = 0.36 μ mol/g dry tissue∙h−1) by increasing the influx of Na (Ji = 0.79 μ mol/g dry tissue∙h−1).
Differences in survival and behaviour of rock ptarmigan (Lagopus mutus) chicks among years in Alaska
Authors: Theberge John B. , Bendell James F.
Published: December 2009

Three successive cohorts of rock ptarmigan chicks were raised in the standard conditions of a controlled environment aviary at the University of Alaska to identify inherent differences in survival and behaviour. That such differences were occurring was suggested by analysis of 10 years of population data. Eggs and chicks less than 4 days old were collected adjacent to the Eagle Creek population study area, representing one cohort at the peak of the cyclic fluctuation in 1968, and one on each side of the peak. Survival to 8 weeks varied among years. Parallel differences occurred in survival of chicks in the wild. Differences also occurred among years in level of agonistic behaviour measured from day 1 to 8 weeks by means of mirror tests. The behavioural differences are also attributed to inherent differences between cohorts. The difference in agonistic behaviour between 1968 and 1969 was primarily due to the greater scores of chicks from adult (2 years or older) hens. In 1969, chicks from adult hens were significantly more agonistic than chicks from yearling hens.
Desiccation resistance in Sphaerium occidentale and Musculium securis (Bivalvia: Sphaeriidae) from a temporary pond
Authors: McKee P. M. , Mackie G. L.
Published: December 2009

The fingernail clams Sphaerium occidentale and Musculium securis often inhabit the same temporary pond. Sphaerium occidentale occurs only in temporary aquatic habitats and M. securis in both temporary and permanent aquatic habitats. Both burrow into the sediment and aestivate when the habitat dries in summer. While aestivating, S. occidentale is more resistant to drying than M. securis, although both species require relative humidities near 100% to survive prolonged atmospheric exposure. A soil moisture level of at least 15% by weight is required by both species to resist desiccation during aestivation in the laboratory. In the dry pond, microhabitats characterised by moist, organic soils support the highest survival rates for both species. To survive aestivation, resistance to desiccation is developed by all length classes of S. occidentale. Only newborn M. securis are able to aestivate.
Dolichodera fluvialis n.gen., n.sp. (Nematoda: Heteroderidae) from Quebec, Canada
Authors: Mulvey R. H. , Ebsary B. A.
Published: December 2009

A new genus, Dolichodera, is proposed to accommodate D. fluvialis, a new species of cyst-forming nematode from aquatic habitat. Cysts of Dolichodera lack a posterior protuberance and are closest to the genus Globodera but differ in shape (elongate–ovoid versus spherical in Globodera), presence of bullae in fenestral area (which are absent in Globodera), and longer tail in second stage larva (95–120 μm vs. 33–63 μm in Globodera). A key to genera of Heteroderidae is provided.
A laboratory study of preferential predation by the newt Notophthalmus v. viridescens
Authors: Attar Etienne N. , Maly Edward J.
Published: December 2009

Experiments were performed to determine if the newt Notophthalmus v. viridescens preferred the amphipod Hyalella over the cladoceran Daphnia under laboratory conditions and how temperature, relative proportion of prey, and total abundance of prey affects prey preference. Experiments demonstrate that Hyalella is the preferred prey at high prey densities but that Daphnia is preferred at low prey densities. Relative density of prey does not affect the preference for Hyalella at high prey density, but reduced temperature eliminates the preference for Hyalella at these high densities. Turbid water reduces the feeding rate.The experimental results can be attributed to hunting behavior of the newt and to size and activity patterns of the prey. The results suggest that the newt is an opportunistic feeder and that prey movement affects numbers of prey eaten.
Tide-related changes of volatile fatty acids in the blood of the lugworm, Arenicola marina (L.)
Authors: Pionetti Jean-Michel , Toulmond André
Published: December 2009

The intertidal lugworm, Arenicola marina, develops a respiratory and metabolic blood acidosis when the oxygen availability is reduced during emersion time at low tide. Measurement of volatile fatty acids in prebranchial blood sampled in the field showed that blood acetate and propionate concentrations increased with length of emersion time. Experimentally confined lugworms excreted acid by-products into the medium when water oxygen tension dropped below 50 Torr (1 Torr = 133.322 Pa) or when oxyhemoglobin concentration fell below 0.45 mmol L−1. A metabolism oriented toward easily excreted end-products may be considered as adaptive in view of the energy yield and the possibility of minimizing metabolic acidosis.
Age-related histological changes in neurosecretory cells in the supraoesophageal ganglion of Nereis virens (Annelida, Polychaeta)
Authors: Bell Kathryn , Marsden Joan R.
Published: December 2009

The supraoesophageal ganglion of Nereis virens has been surveyed by light microscopy to determine the locations of probable neurosecretory cells. Neurons reacting with paraldehyde fuchsin are found scattered throughout the brain, but the majority are accumulated posteriorly in nucleus 20. This nucleus was examined in some detail, and the histology of four cell types is described. Two types (p and r) are strongly paraldehyde-fuchsin-positive, and may be secretory. On the basis of other staining characteristics, and uptake of labelled cystine, it is concluded that p cells are rich in cystine and (or) cysteine. A comparison of juvenile and adult brains revealed that the same cell types exist at both developmental stages, but that p and r cells increase in number and staining intensity with age. These findings are not consistent with the notion that these particular cells are the source of a "juvenile hormone' ' which has been reported to exist in nereids. Rather it is suggested that the described cells are producers of a maturation and (or) spawning hormone.
Audition in spring species of arctiid moths as a possible response to differential levels of insectivorous bat predation
Authors: Fullard James H. , Barclay Robert M. R.
Published: December 2009

We used neurophysiological analyses to determine that arctiid moths which emerge, as adults, during the spring possess tympanic organs responsive to ultrasonic stimuli similar to the echolocation signals of bats. These species, however, do not express another form of bat-directed defense: sound production. Both audition and sound production are present in those species which are volant in the summer months. We suggest that the predation pressure exerted by populations of sympatric, insectivorous bats (Myotis lucifiigits) increases during the season as a result of the foraging patterns of lactating females and, later, their juveniles. Whereas this pressure is low enough in the spring to allow arctiids to exist with only the long-range defense of audition, by summer it has increased sufficiently for selection to favour the presence of short-range defenses (i.e. sound production).
Purification and characteristics of the chloride transport stimulating factor from locust corpora cardiaca: a new peptide
Authors: Phillips J. E. , Mordue W. , Meredith J. , Spring J.
Published: December 2009

Corpora cardiaca (CC), cAMP, and hemolymph all increase short-circuit current (Isc) and electropotential difference (PD) across locust rectum by stimulating electrogenic transport of Cl− from the lumen. Using ΔIsc as a bioassay, we have purified the water-soluble stimulant (CTSH) from CC using gel filtration chromatography, DEAE-Sephadex anion exchange, cellulose acetate electrophoresis, and thin-layer chromatography. A single peak of CTSH activity was observed after all these procedures, although small amounts of CTSH activity occasionally remained in the high molecular weight (MW) protein precipitate. CTSH was purified more than 100-fold on Bio-Gel P-30 columns. It has a MW of 8 000 – 12 000, is destroyed by trypsin digestion, and has a net negative charge over the pH range (5–10) at which it is most stable. Various properties (i.e., stability at 20 °C, localization in CC, MW, Rf values) and reciprocal bioassay s indicate that CTSH is different from diuretic, antidiuretic, and adipokinetic hormones from locust CC. No difference in the properties of CTSH from glandular (GL) and storage lobes (SL) of CC were noted, although 80% of activity was in the SL. The concentration of purified CTSH required to cause maximal stimulation of rectal Isc is less than 7 nM.
Development and stability of single-parent family units in the song sparrow
Authors: Smith James N. M. , Merkt Juan R.
Published: December 2009

Allocation of parental feedings to newly fledged young was observed in 34 song sparrow broods on the day of leaving the nest (day 0) and in five more broods the subsequent day (day 1). In the one case in which leaving the nest was observed, feedings were immediately divided between parents so that each young was fed by only one parent. Four-fifths of all young were fed by only a single parent on day 0 or day 1: the remaining fifth were fed by both parents during observation periods of about 90 min. Twenty-nine of the same broods were observed again during days 4–8, when only 1 of 82 young was fed by both parents. Slightly more young were fed by males than on days 0–1. The tendency for males to care for a higher proportion of older young occurred whether or not the pair began a further brood. Song sparrow fledglings gave individually distinct food begging calls. These may have assisted the formation or maintenance of specific parent–young feeding units. Brown-headed cowbird young in the brood were treated like song sparrows, except that they were fed more frequently.
Habitat use and response to patches of prey by desert insectivorous bats
Authors: Bell Gary P.
Published: December 2009

I examined the habitat use patterns of an Arizona insectivorous bat community using ultrasonic sensing equipment which allowed field identification of bat species based on their echolocation calls. Response to prey patchiness by the species encountered was tested using ultraviolet lights to attract swarms of insects. No partitioning of habitat or time was observed, there being a high degree of species overlap, and many species of bats appeared to be positively associated. All species responded to light-induced prey patches on at least some occasions. Analysis of prey populations indicated that food, though abundant, was extremely patchy in distribution, both spatially and temporally. These data indicate a bat community in which species are highly adapted to an abundant, but patchy food source.
The copepod width–weight relation and its utility in food chain research
Authors: Pearre Jr. Sifford
Published: December 2009

A review of several methods for estimating copepod wet weight from linear dimensions shows that, as expected, precision in estimation is gained at the expense of generality. Body width, however, is a better estimator of wet weight than either total length or prosome length and is less ambiguous in use.Body width is also the controlling parameter in prey selection by many important marine and freshwater predators including birds, fish, and some plankters. For estimating ingested prey biomass it thus seems the best single linear size parameter.
Lesions caused by Diplotriaena tricuspis (Nematoda: Diplotriaenoidea) in the American crow, Corvus brachyrhynchos Brehm
Authors: Cawthorn Richard J. , Anderson Roy C. , Barker Ian K.
Published: December 2009

Lesions in crows (Corvus brachyrhynchos Brehm) experimentally infected with Diplotriaena tricuspis (Fedtschenko, 1874) Henry and Ozoux, 1909 were studied. Larvae caused traumatic lesions during their movements through the hepatic portal system. Giant cell granulomas surrounded dead nematodes in the liver and its capsule. Some eggs were encapsulated in the hepatic capsule and subcapsular parenchyma. Chronic liver inflammation, including lymphoid hyperplasia, occurred.Various pulmonary lesions developed, including oedema, fibroplasia, infiltrations, haemorrhage, periarteritis, endothelial swelling and vacuolation, lymphoid hyperplasia, congestion, and thrombosis. Giant cell granulomas, containing living and dead nematodes, occluded parabronchi and secondary bronchi. Pulmonary inflammation persisted although most live D. tricuspis had moved into the air sacs by 45 days. Aspirated eggs evoked granulomatous pneumonia and mucoid hyperplasia of bronchiolar epithelium.In air sacs a few live D. tricuspis were surrounded by an acute inflammatory reaction. Dead nematodes were enclosed in giant cell granulomas. Rarely, air sacs were discoloured and roughened, and excess frothy fluid was present. Eggs encapsulated in fibrous tissue in the wall of air sacs were noted. Clinical signs were observed in only 1 of 44 experimentally infected crows.
Prediction of energy expenditures by Rocky Mountain bighorn sheep
Authors: Chappel R. W. , Hudson R. J.
Published: December 2009

Factors influencing the metabolic rate of two adult male and two adult female Rocky Mountain bighorn sheep (Ovis canadensis) were analyzed by multiple classification analysis. Factors considered were sex, date, body weight, exposure temperature, adaptation temperature, time since last feeding, and previous gross energy intake. The overall mean energy expenditure was 11.012 MJ∙day−1 (460 kJ∙kg−075∙day−1). When factors were tested independently, body weight, sex, and exposure temperature, in order of importance, contributed significantly to differences in energy expenditures. The total statistical model accounted for 87% of variance. Metabolic rate increased with body weight and previous gross energy intake and decreased with adaptation temperature, exposure temperature, and fasting. Metabolic rates of males were higher than of females. An underlying seasonal cycle in resting metabolic rate was observed.
Seasonal variation in two species of unionid clams from Manitoba, Canada: biomass
Authors: Huebner Judith D.
Published: December 2009

The relationship between dry weight and shell length for Anodonta grandis and Lampsilis radiata is log dry weight = a + 3.0317 log shell length, where a varies seasonally. Average water content of clams varies seasonally from 83.18% for both species in February and May to 85.02% for L. radiata in July and 87.56% for A. grandis in July and October. Mean ash content of L. radiata (19.21%) is higher than that of A. grandis (12.68%) except in October (20.94%) when marsupia are filled with glochidia. Differences in reproductive timing and length of glochidial retention contribute to some of the seasonal variations in biomass in A. grandis and L. radiata.
The influence of temperature on energy budget variables, body size, and seasonal occurrence of the isopod Idotea baltica (Pallas)
Authors: Strong Kim W. , Daborn Graham R.
Published: December 2009

Effects of temperature on ingestion (C) and metabolic (R) rates in Idotea baltica are examined to explain differences in maximum body size, longevity, and seasonal occurrence in two populations occupying habitats differing by 2–4 °C in average maximum temperature. Results illustrate that C and R are differentially affected by temperature such that the value C – R varies considerably with both body size and temperature. These data indicate that small isopods (< 20 mg) would grow most rapidly at the highest temperature studied (14 °C), whereas larger animals have maximum C – R values, and presumably grow most rapidly, at cooler temperatures (ca. 9 °C). The pattern explains why the population at the lower temperature lives twice as long, grows to much larger size, and apparently leaves the intertidal zone for a longer period than do those living in the similar warmer habitat. The results are discussed in relation to phenomena noted in other marine and freshwater crustacean populations.
Eimeria canadensis (Protozoa, Sporozoea): ultrastructure of the host–parasite interface during development of first-generation schizonts in vitro
Authors: Mueller Bodo E. G.
Published: December 2009

Eimeria canadensis sporozoites were inoculated into monolayer cultures of Madin–Darby bovine kidney and primary bovine embryonic kidney cells. Sporozoites retained their shape for at least 9 days. At that time, the nucleus was enlarged and contained a prominent nucleolus, and amylopectin granules were no longer apparent. The width of the parasitophorous vacuole (pv) between host cell cytoplasm and parasite pellicle widened during transformation of sporozoites into multinucleate schizonts. Areas of altered host cell cytoplasm immediately adjacent to the pv membrane increased in size and became confluent, resulting in the formation of two distinct layers of cytoplasm. The outer zone contained the host cell nucleus, mitochondria, Golgi stacks, and ER, whereas the inner layer appeared granular and was void of all cell organelles except structures resembling ribosomes. Microfilaments were abundant at the border between inner and outer zone. In the most advanced stages observed, host cell organelles persisted only in the perinuclear region. The remaining, attenuated cytoplasm resembled the former inner zone.The novel ultrastructural observation of a bilayered cytoplasm of cells harbouring E. canadensis schizonts is compared with light microscope reports of similar effects caused by other Eimeria species of ruminants and with electron microscope findings of altered intestinal and abomasal cells of sheep harbouring "globidial" schizonts.
Ecological genetics of threespine sticklebacks in Heisholt Lake
Authors: MacLean Jim
Published: December 2009

A series of experiments were conducted to examine interactions between the genetics and ecology of threespine sticklebacks in Heisholt Lake. Frequencies of plate phenotypes varied spatially between both areas and depths of the lake and temporally within and between generalions. Movement experiments showed that the population is composed of residents, who remain in a restricted area and appear lo maintain either a breeding or a feeding territory, and nonresidents, who move between areas. The plate phenotype of a stickleback influenced its chances to become a resident, but the favored phenotype varied in both space and time. Rare phenotypes appeared to have an advantage in competition for territories and increased in relative frequency within cohorts. Density of sticklebacks also influenced the fitness of phenotypes.These observations suggest the hypothesis that the observed spatial and temporal changes in plate phenotype frequencies were the result of competition between phenotypes for territories.
Comparison of egg size and related life-history characteristics for two predaceous tree-hole mosquitoes (Toxorhynchites)
Authors: Lamb R. J. , Smith S. M.
Published: December 2009

Certain life-history characteristics of Toxorhynchites brevipalpis and Tx. rutilus septentrionalis were compared in the laboratory with the aim of accounting for a more than twofold difference in the weight of their eggs. First- and second-instar larvae of Tx. rutilus were longer and third-instar larvae shorter than corresponding stages of Tx. brevipalpis. The sizes of the two species did not differ appreciably in the later stages. Toxorhynchites rutilus first-instar larvae consumed more prey but total prey consumption was much greater for Tx. brevipalpis due to differences in consumption during the fourth instar. Developmental times from egg to adult did not differ at 25 °C. Toxorhynchites brevipalpis produced twice as many eggs per day during the first 14 days of oviposition but, due to size differences, the weight of the eggs produced per day was equal for the two species. Female Tx. brevipalpis laid an average of 5.9 eggs per oviposition flight. A corresponding value for Tx. rutilus was not determined. Newly hatched Tx. brevipalpis larvae withstood starvation for a longer period of time than Tx. rutilus larvae. Larval Tx. rutilus captured and consumed larger prey.It is hypothesized that egg size and fecundity are adapted to prey size and heterogeneity in prey availability in the natural environments of the two species.
Plasma concentrations of testosterone and luteinizing hormone in rutting reindeer bulls (Rangifer tarandrus)
Authors: Stokkan K.-A. , Hove K. , Carr W. R.
Published: December 2009

Concentrations of plasma testosterone and luteinizing hormone (LH) were measured in peripheral plasma from semidomestic, rutting reindeer bulls. Although the concentrations of plasma testosterone were high and showed large variations, those of LH were low and only a few episodic bursts could be detected in hourly samples taken throughout a 48-h period. The mean testosterone concentration in three bulls differed significantly and ranked the animals according to their position in a fighting hierarchy. The mean concentrations of LH did not differ significantly. Plasma samples from one reindeer bull sampled every 20 min for periods of 3 h indicated that an increment in LH concentration preceded a peak in testosterone. No diurnal pattern in testosterone concentrations could be detected, but testosterone peaks seemed to appear about every 3–4 h. The present study thus demonstrates that a series of plasma samples throughout the day is necessary to determine a true "testosterone level" in the reindeer bull.
Morphological and physiological (i.e., upper lethal temperatures) comparisons between Notropis cornutus (Mitchell) and Notropis chrysocephalus (Rafinesque) from the Grand River, Ontario
Authors: Kott Edward , McCauley Robert W. , Humphreys Gregory
Published: December 2009

Two forms of the Notropis cornutus (Luxilus) complex occur syntopically in the Grand River system. These have been interpreted by some authors as separate species and by others as subspecies. The forms can be distinguished morphologically by the number of predorsal scales and by pigmentation pattern. It has also been suggested that the upper lethal temperatures of the two differ.This is the first report of a study of these features in syntopic populations. The results indicate that neither physiological nor morphological characters can establish the taxonomic status of these forms and that what is needed is a detailed study of the breeding behaviour of these forms in areas of syntopy.
Undulatory median fin propulsion of two teleosts with different modes of life
Authors: Blake R. W.
Published: December 2009

A simple fluid flow model, based on momentum considerations, is employed to calculate the hydromechnanical efficiency of the undulatory dorsal fin propeller of the electric fish (Gymnarchus niloticus) and the seahorse (Hippocampus hudsonius). The undulatory fins of G. niloticus and H. hudsonius are representative of two extreme kinematic styles. The dorsal fin of G. niloticus is characterized by waveforms which are propagated at low frequency and a leading edge which "sweeps out" a large area. In contrast, the leading edge of the dorsal fin of H. hudsonius sweeps out a comparatively small area and waveforms pass down the fin at a high frequency. It is shown that the propulsive efficiency of the dorsal fin of G. niloticus can be up to twice that of H. hudsonius at similar swimming speeds. Possible explanations for the evolution of the two kinematic modes are discussed in relation to the mode of life of the animals.
Thick-billed murres and black guillemots in the Barrow Strait area, N.W.T., during spring: diets and food availability along ice edges
Authors: Bradstreet Michael S. W.
Published: December 2009

From 5 June to 4 July 1976, I collected 98 thick-billed murres (Uria lomvia) and 47 black guillemots (Cepphus grylle) at ice edges in Barrow Strait, N.W.T., for diet studies. Alcids were collected at coastal ice edges and at the edges of landfast ice farther offshore; in both habitats food availability was also studied. At coastal ice edges, murre diet was dominated by Arctic cod (Boreogadus saida, 14% of dry weight biomass) and the amphipod Onisimus litoralis (18%); guillemot diet was dominated by cod (99%), decapods (0.4%), and amphipods (0.2%). At offshore ice edges murres took cod (96%), Parathemisto (2%), and Onisimus glacialis (2%); guillemots took cod (54%), O. glacialis (35%), and Apherusa glacialis (5%). Morisita's overlap values showed that diets of these two alcids were more similar at offshore than at coastal ice edges and that there were considerable habitat-related differences in diet. Data on food availability suggested that at offshore ice edges, murres were feeding in the water column and at the undersurface of the landfast ice; guillemots fed almost solely at the ice undersurface. At coastal ice edges, both alcids were probably feeding at the ice undersurface and on the sea bottom; in addition, murres fed in the water column. The importance of epontic (= ice-associated) fauna in the diets of alcids during spring is discussed.
A preliminary account of brain growth in postlarval Nereis virens (Polychaeta: Annelida): a [3H]thymidine study
Authors: Easdown Jane , Marsden Joan , Paradis Khazal , Bell Kathryn , Jost Judith
Published: December 2009

Labelling of the supraoesophageal ganglion of postlarval Nereis virens with [3H]thymidine indicates that cell division is most active in very small worms, less than 0.1 g in weight. In such animals a few, small, labelled neurons were found, but only after 13 h of exposure to isotope. After shorter exposures, very small, undifferentiated labelled cells were seen in most of the ganglionic areas of the brain, although the various ganglionic nuclei differ in the time of first appearance of their characteristic neurons. In older animals gliagenesis continues at a reduced rate and neuron production becomes extremely slow.
A technique for fish specimen photography in the field
Authors: Emery Alan R. , Winterbottom Richard
Published: December 2009

A field-tested method for setting and photographing freshly dead fishes using three different sized aquaria each with a free adjustable glass plate inside was found efficient for processing different sized fishes. A V-shaped frame of aluminum mounted on a tripod carried two flash units. The angle of the V was calculated to eliminate reflection from the walls of the aquaria, and the camera was hand held. The above combination allowed extremely rapid processing of specimens and could be applied to organisms other than fishes. We believe this technique, possibly with minor modifications, will prove effective in many fields of natural science where the size or nature of specimens does not preclude it, and where photographic documentation of large numbers of fresh specimens is desirable.
The ecology of blood parasites in blue grouse from Vancouver Island, British Columbia
Authors: Williams Norman A. , Mahrt Jerome L. , Zwickel Fred C.
Published: December 2009

The blood parasites in blue grouse (Dendragapus obscurus (Say, 1823)) from Vancouver Island, British Columbia were studied during the summers of 1972 through 1975. Data from 1707 birds of three age-classes indicated that infections of Leucocytozoon bonasae occurred more often (79%) than Trypanosoma avium (54%), Haemoproteus mansoni (42%), or microfilariae (37%). Concurrent associations of these taxa were more common (77%) than single species infections. Frequencies of multiple species infections did not fit expected probabilities, indicating that multiple associations are not derived independently.Young grouse acquire L. bonasae and H. mansoni by middle to late June, 2–3 weeks after hatching. Infections of T. avium and microfilariae appeared 4 and 5–9 weeks after hatch, respectively. Leucocytozoon and Haemoproteus had two transmission periods which varied seasonally among years, but which had similar within-year patterns. Simulium aureum was incriminated as a vector of L. bonasae, but attempts at experimental transmission were not made. The utilization of common species of vectors by several taxa of parasites is postulated. Competitive exclusion does not appear to exist for this species assemblage.