bluuebunny/crossref_metadata_2025 huggingface dataset:
The foraging behaviour and ecology of animal-eating bats
Authors: Fenton M. Brock
Published: August 2008

The results of recent studies of the foraging behaviour of animal-eating bats are considered in this review. The advent of small (< 1 g) radio transmitters has made it possible to collect data on individual variations in foraging behaviour for species with body mass over 15 g. These data can be combined with those from wing morphology and echolocation call design to assess the flexibility achieved by some bats. The information concerning bats can be placed in a broader perspective by considering it in the light of current ideas about foraging theory. In this review, information about bat foraging is considered in the context of structural and functional features, the former relating to bats' access to habitats of different complexity and the latter to their behavioural responses. Mechanical features involving wing morphology and perceptual features, such as the ability of echolocating bats to deal with clutter, combine to influence the behavioural flexibility of individuals. This, in turn, affects access to prey and patterns of community structure. Bats relying on airborne prey appear to be limited to small prey items, whereas those hunting nonairborne targets may take much larger prey. Variation in individual behaviour means that terms such as gleaning, perch hunting, piscivory, and carnivory do not accurately define the foraging of animal-eating bats. Morphological and behavioural data suggest that sympatric animal-eating bats of similar size will show considerable overlap in prey taken and in patterns of habitat use.
Factors affecting colony attendance by Ancient Murrelets (Synthliboramphus antiquus)
Authors: Jones Ian L. , Gaston Anthony J. , Falls J. Bruce
Published: August 2008

We studied factors influencing variation in nightly levels of activity (birds arriving and vocalizing) and numbers of birds staging offshore at a colony of Ancient Murrelets at Reef Island, British Columbia, during 1984, 1985, and 1986. Activity was restricted to the hours of darkness and extremely variable in magnitude from night to night. The rate of entry into burrows tended to decrease, and the amount of vocalization and numbers of birds at the staging area increased during the nesting season. We detected an underlying 4-day cyclical pattern of attendance. Nightly variability of activity at the colony was affected by moonlight and weather conditions. Since activity, particularly vocalization, was reduced on moonlit nights, we suggest that nocturnal colony attendance is a strategy to avoid diurnal predators in this species. The largest numbers of birds were present and vocalizing at the colony on calm moonless nights. Weather conditions explained a substantial proportion of the night to night variability in murrelet activity. Among weather variables, wind speed had the most consistent effect and was particularly important in 1985. Both short-term, i.e., of a particular night, and long-term, i.e., over the previous 3 days, conditions influenced activity. Our observations suggest that direct weather effects at the colony may be more important than weather effects related to foraging conditions. Interyear differences in activity may have resulted from the interaction of weather and general foraging conditions.
Seasonal cycles of activity and inactivity in some hydroids from Virginia and South Carolina, U.S.A.
Authors: Calder Dale R.
Published: August 2008

Hydroids investigated in estuaries of Virginia and South Carolina, USA, were characteristically seasonal in occurrence. Of 20 species studied in Virginia, 14 were active only during warmer months and 6 only during colder months of the year. Seven of the 18 species examined in South Carolina were active all year, whereas 9 were active only in warmer months and 2 only during colder months. Reflecting the differing temperature regimes of the two study areas, warm-water species were active for a longer period of time in South Carolina than in Virginia; cold-water species were active longer in Virginia than in South Carolina. Warm-water species commenced activity in late winter or spring at higher temperatures than those coinciding with hydranth regression in autumn or early winter. Activity in cold-water species began at lower temperatures than those observed at regression in spring. Correlations were apparent in the seasonality, water temperature tolerances, and latitudinal distribution of most species. Field observations and laboratory experiments demonstrated that a number of species survived unfavourable periods as dormant coenosarc in stems and stolons. With the return of favourable conditions, new growth began and hydranths were regenerated from dormant tissue. Water temperature is considered the prime factor influencing the seasonal activity–inactivity cycles of hydroids in the two study areas.
Intra- and inter-specific dominance relationships among arctic and snowshoe hares
Authors: Fitzgerald Shannon M. , Keith Lloyd B.
Published: August 2008

The geographic ranges of arctic and snowshoe hares (Lepus arcticus and L. americanus) rarely overlap. In Newfoundland and elsewhere in North America, arctic hares occupy treeless barrens or tundra, whereas snowshoe hares inhabit forest. We explored the hypothesis that such allopatry reflects interference competition, an agonistic interaction in which snowshoe hares are behaviourally dominant. To assess both inter- and intra-specific dominance, we conducted a series of dyadic trials in outdoor pens and also observed interactions of free-ranging individuals. Five testable predictions were inferred, a priori, from competition theory and previous leporid studies: (i) heavier individuals are dominant, (ii) adults dominate juveniles, (iii) females dominate males when both are in breeding condition, (iv) males dominate females when neither are in breeding condition, and (v) adults in breeding condition dominate those that are not. With snowshoe hares, tests for predictions i and ii were inconclusive, and iii was probably verified (P = 0.03). With arctic hares, test results were inconclusive for i, verified for ii (P < 0.01), and rejected for iii and iv, dominance being unrelated to sex or breeding condition. Prediction v could not be tested intraspecifically, but arctic hares dominated snowshoe hares in 84 of 85 dyads, including those where snowshoes weighed more, or were in breeding condition and arctic hares were not. It is, therefore, highly unlikely that interference competition with snowshoe hares is responsible for the current restriction of arctic hares to barrens and tundra.
Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) on Svalbard
Authors: Ryg Morten , Smith Thomas G. , Øritsland Nils Are
Published: August 2008

Seasonal changes in body mass and body composition of ringed seals (Phoca hispida) from the Svalbard Islands are described. The blubber content of adult females decreased from a high of about 50% at the beginning of the pupping season in March–April to a low of 31% during moulting in June. In adult males, the blubber content decreased from 41% in March to 29% in June. By estimating an individual seal's body mass by 1 April from its standard body length, we calculated an average daily loss of body mass of 160 g/day in adult females and 100 g/day in adult males from the start of lactation to the middle of moulting. The blubber content of sexually immature seals was less in June and July than in April, but the seasonal changes were smaller than in adult seals. We found no evidence of significant changes in core mass in adult seals, and suggest that the seasonal body mass changes are mostly due to changes in body fat content.
Histochemistry, innervation, capillary density, and mitochondrial volume of red and white muscle fibers isolated from a lizard, Varanus exanthematicus
Authors: Mutungi Gabriel
Published: August 2008

Fiber types in the iliofibularis muscle of the savannah monitor lizard, Varanus exanthematicus, have been characterized on the basis of their histochemical characteristics and nerve endings. Four types of fibers were identified, three of which were focally innervated and the other, multiply innervated. They corresponded to the fast glycolytic, fast oxidative glycolytic, slow oxidative, and tonic fiber types of other lower vertebrates. The fibers isolated from the white and most of the fibers from the red regions had well defined end plates. However, 15 to 20% of the fibers isolated from the red region possessed an average of 17 ± 0.5 end plates per fiber. These end plates were placed 922 ± 54 μm apart and poorly defined. The mitochondrial volume of fibers isolated from the red region (12 ± 0.5%) was six times that of fibers isolated from the white region (2 ± 0.1%). Myofibrillar volumes were similar in fibers isolated from the two regions (81 ± 0.6%, white; 77 ± 0.2%, red). However, the capillary density of fibers from the red region (932 ± 64/mm2) was four and one-half times that of fibers isolated from the corresponding white region (200 ± 35/mm2).
The laying of male eggs by bumble bee queens: an experimental reappraisal and a new hypothesis
Authors: Plowright R. C. , Plowright C. M. S.
Published: August 2008

The hypothesis that proximal factors associated with high worker density in a bumble bee (Bombus terricola) colony trigger laying of male eggs by the queen was examined in a series of four experiments. Neither the age of workers, the presence or absence of laying workers, nor the amount of pollen available to the colony affected the date of first male egg laying. Moreover, queens that had begun laying male eggs did not revert to laying female eggs after being removed from their colonies and placed in isolation. Instead, onset of male egg production appeared to be associated with the date of attainment of a critical worker/larva ratio in the colony. Functional considerations lead to the new hypothesis that queens monitor their egg-laying performance and begin to lay male eggs when it can be predicted that their female eggs will be raised as young queens.
Empirical and physiological assessment of in vitro growth in the mermithid nematode Romanomermis culicivorax
Authors: Gordon Roger , Cornect Marcel , Young Terry-Lynn , Kean Kenneth T.
Published: August 2008

In vitro growth of Romanomermis culicivorax preparasites was monitored in two culture media under differing conditions of crowding. Crowding was more important than the character of the medium itself in stimulating in vitro growth. The glycogen, protein, and lipid content of nematodes that had developed after 5 weeks under crowded conditions was significantly greater than that of uncrowded nematodes. The lipid content of such crowded nematodes was greater than that of nematodes after 4 days of in vivo development, although glycogen and protein levels were lower than the 4 day in vivo norm. Nematodes that had developed in vitro contained a higher proportion of long-chain and polyunsaturated fatty acids than did nematodes cultured in vivo. The significance of these findings is discussed in relation to the establishment of a continuous in vitro culture system for this nematode.
Effects of cyclic food supply on breeding performance in Tengmalm's owl (Aegolius funereus)
Authors: Hörnfeldt Birger , Carlsson Bengt-Göran , Löfgren Ola , Eklund Ulf
Published: August 2008

Cyclic populations of bank voles (Clethrionomys glareolus), grey-sided voles (Clethrionomys rufocanus), and field voles (Microtus agrestis) made up > 90% of the diet of Tengmalm's owl (Aegolius funereus) in northern Sweden during the breeding seasons of 1980–1986. These voles also made up > 90% of snap-trapped small mammals in the study area. Comparisons of the species composition in the diet during laying with that of animals trapped indicated that bank voles were usually taken approximately in proportion to their relative abundance, whereas field voles were frequently taken more and grey-sided voles less than expected from their relative abundance. However, bank voles predominated in the diet during laying early in the season (snow depth > 40 cm). Later in the season (snow depth ≤ 40 cm) the porportion of field voles and grey-sided voles increased during laying, suggesting increased availability of these species as the snow melted. Breeding density (percentage of nest boxes with ≥ 1 egg) showed a positive correlation whereas laying date showed a negative correlation with food supply in autumn. In contrast, clutch size, number of fledglings per successful nest, and an index of the annual production of fledglings showed positive correlations with food supply in spring. Clutch size declined with season but at different levels in different years, and laying date per se only explained 11% of clutch size variation among years. In contrast, the "year effect" (related to food supply) explained 29% of the variation in clutch size. Clutches were even larger at later laying dates (when, however, the food supply was better) in 1984 than in 1985. Nest survival and survival per egg (until fledging) in successful nests varied over the years, but did not covary with the cyclic food supply. However, the lowest nest survival was found in a year when voles declined dramatically over winter. Egg size did not show any variation among years.
Rheotaxis in Otocinclus sp. (Teleostei: Loricariidae)
Authors: Macdonnell A. J. , Blake R. W.
Published: August 2008

Observations were conducted to determine rheotaxic behavior in Otocinclus sp. (Loricariidae). Rheotaxis in Otocinclus sp. (standard length 2.29–3.34 cm) occurs in three stages; (i) resting at zero water velocity; (ii) adhesion when water velocities are increased to about 10 cm s−1; and (iii) clamped position when slipping occurs (between 19 and 35 cm s−1). Rheotaxis also occurred on rougher surfaces without displacement for water velocities up to 70 cm s−1. Slipping velocities are maximized by morphological and behavioral characteristics that allow for the maintenance of position in rapidly moving water.
A report of Thelohanellus notatus (Mavor) (Myxozoa) from Notropis hudsonius (Clinton) (Cyprinidae) in Ontario
Authors: Beis M. J. , Cone D. K.
Published: August 2008

Thelohanellus notatus (Mavor) is reported from young of the year Notropis hudsonius (Clinton) (Cyprinidae) in Lake Mindemoya, Manitoulin Island, Lake Huron, Ontario. The parasite produced large cysts (1–5 mm in diameter) in body musculature and mesenteries, with aggregations occurring at the base of fins. Forty-six of 47 fish were infected. Intensity was unusually high at 2–30 cysts per fish. The study is the first report of the parasite from Manitoulin Island and from N. hudsonius.
Total available carbohydrates in Aedes stimulans (Diptera: Culicidae)
Authors: Magnarelli Louis A.
Published: August 2008

Laboratory-reared and field-collected females of Aedes stimulans (Walker) were individually analyzed for total carbohydrate, the chief source of energy for flight. Relatively low amounts of carbohydrate [Formula: see text] were available in unfed, newly emerged females that had been reared from field-collected pupae and frozen less than 12 h after eclosion. Mean values for 887 blood-seeking females varied greatly when samples were collected on different days [Formula: see text] or during periods of the same day [Formula: see text]. In some instances, the total amounts of carbohydrate present in blood-seeking females were equivalent to those of starved individuals [Formula: see text].
Mechanisms of sibling recognition in meadow voles
Authors: Ferkin Michael H. , Rutka Timothy F.
Published: August 2008

The purpose of this study was to determine whether sibling recognition in meadow voles (Microtus pennsylvanicus) resulted from familiarity through common rearing or from identification of kin via phenotype matching. The first experiment clearly demonstrated that sibling recognition occurs among meadow voles. Individuals preferred the odor of familiar siblings to the odor of unfamiliar nonsiblings, and agonistic acts were less frequent between sibling than between nonsibling dyads. The second experiment examined whether sibling recognition resulted from familiarity and genetic relatedness. Meadow voles preferred the odor of littermates to the odor of nonlittermates. Full siblings do not share olfactory cues or signatures unique to that litter. Meadow voles behaved agonistically toward unfamiliar full siblings, but not toward familiar nonsiblings. Reduced agonistic behavior between and preferences for littermates versus nonlittermates, independently of genetic relatedness, suggest that among meadow voles sibling recognition is based on prior association through common rearing.
Are roads barriers to dispersal in the land snail Arianta arbustorum?
Authors: Baur Anette , Baur Bruno
Published: August 2008

The effect of road width on dispersal in the land snail Arianta arbustorum was examined by recording displacements of marked individuals during one activity season (3 months) in central Sweden. For two sites, a paved road (8 m wide, low traffic density) and an unpaved track (3 m wide), the snails' movements were largely confined to roadside verges. The snails followed the vegetation belts; the average displacements ranged from 1.5 to 4.9 m at different sites. Several snails covered large distances, the maximum recorded being 14 m. Despite these long-distance dispersers, only one of the recaptured snails crossed the paved road and two crossed the track, indicating that the road and, to a minor extent, the track acted as dispersal barriers. By contrast, an overgrown path (0.3 m wide) did not influence the snails' movement. Our results suggest that snail populations separated by paved roads with high traffic densities may be isolated from each other.
Growth of embryonic softshell turtles is unaffected by uremia
Authors: Packard Gary C. , Packard Mary J.
Published: August 2008

We injected eggs of softshell turtles (Trionyx spiniferus) with solutions of urea at the midpoint of incubation to induce different levels of uremia in developing embryos. The experiment was undertaken as a test of the hypothesis that urea inhibits intermediary metabolism of embryos and thereby causes a reduction in their rates of growth. The injection protocol elicited a physiologically realistic range of uremias, but we found no evidence that metabolism or growth of embryos was impaired even at the highest levels of uremia. The most likely explanation for our results is that the uremias commonly encountered during natural incubation by embryos of this and other species of turtle are insufficient to inhibit intermediary metabolism. Thus, the influence of the hydric environment on metabolism and growth of embryonic turtles apparently is not mediated by differential rates of increase in the concentration of urea in body fluids.
Differences in bird abundance in relation to proximity of Merlin nests
Authors: Sodhi Navjot S. , Didiuk Andrew , Oliphant Lynn W.
Published: August 2008

Point counts made at different distances from Merlin (Falco columbarius) nests revealed that there were fewer birds near the nests than further away. All species showed this trend, regardless of the likelihood of predation by the Merlins. We propose that this is primarily an avoidance reaction of birds towards nesting Merlins to avoid predation and (or) potential injuries. Point counts made after the Merlins left their nests showed that the number of birds was independent of the distance from the nests.
Seasonal changes in whole brain amine levels of white sucker exposed to elevated levels of copper and zinc
Authors: Munkittrick K. R. , Martin R. J. , Dixon D. G.
Published: August 2008

Levels of dopamine, serotonin, and noradrenalin were measured in whole brains collected from white sucker (Catostomus commersoni) exposed to increased waterborne levels of copper and zinc associated with mining wastes. Few differences were detected between sites, and these findings are consistent with previous studies that failed to indicate chronic, direct effects of the metals on the white sucker populations. Levels of dopamine and serotonin were higher during postspawning periods than during prespawning or spawning. Noradrenalin levels showed parallel trends, although the differences were not significant owing to higher variability. Serotonin levels showed significant circadian variation at both sites, especially during the spawning season. Dopamine levels also showed circadian fluctuations, but only in females at one site. The results are discussed in relation to the potential use of whole brain amine levels as indicators of contaminant impact.
Effect of hypoxia on hemoglobin isomorph abundances in rainbow trout, Salmo gairdneri
Authors: Marinsky C. A. , Houston A. H. , Murad A.
Published: August 2008

To further assess the hypothesis that differential hemoglobin isomorph formation may be involved in the respiratory response of rainbow trout (Salmo gairdneri), yearling animals were first rendered acutely anemic by immersion in phenylhydrazine HCl. Erythropoiesis was then induced by gradual warming under normoxic and hypoxic conditions. While no significant differences in hemoglobin content were observed, trout exposed to hypoxia displayed transient, but significant differences in hematocrit. Significant variations in both the occurrence and abundance of specific isomorphs were also observed.
Spawning tactics of female Miyabe charr (Salvelinus malma miyabei) against egg cannibalism
Authors: Maekawa Koji , Hino Teruaki
Published: August 2008

The number of times a female Miyabe charr, Salvelinus malma miyabei, will spawn in a single nest decreases with the number of males resident in the stream (so-called sneakers or streakers) that are gathered around the breeding pair. The cumulative egg-predation attempts of resident males probably increases with their number. Females apparently distinguish between fertilization and egg-eating attempts of resident males. From our observations that females deposit more eggs during the first spawning in a nest, we have developed a simple graphical model to suggest that this behaviour has evolved as a tactic against egg predation by resident males in the stream.
Behavioural differences between locally recruiting and dispersing gray squirrels, Sciurus carolinensis
Authors: Pasitschniak-Arts M. , Bendell J. F.
Published: August 2008

We tested the hypothesis that recruitment into a resident population involved the selection of an independently defined behavioural type of animal. Gray squirrels were captured in or shortly after leaving their nests, held in the laboratory in a similar manner, and their behavioural profiles and other properties were determined. The following spring, they were released into the area where most were captured and which we virtually emptied of residents prior to the release. Sixty days following the release, 64% (18/28) of the squirrels had dispersed, most before 10 days, and the remainder recruited and became residents. From the laboratory tests, local recruits compared with dispersers were on average more aggressive. There were no clear differences between the two types in mass, tail length, and sex ratio. All were sexually immature. Recruits were more active than dispersers in December, and activity of both appeared to decline from November to April. Proportionately more of the pepper morph recruited than of the black and gray morphs. There appear to be genetic behavioural and colour morph differences among squirrels that affect or are linked to their local recruitment or dispersal and population regulation.
The locomotion of the comatulid Florometra serratissima (Echinodermata: Crinoidea) and its adaptive significance
Authors: Shaw G. D. , Fontaine A. R.
Published: August 2008

Swimming and crawling activities are described from observations made in situ during SCUBA diving and in aquaria. Initial vertical swimming lifts the crinoid to 29 cm mean height. Subsequently, horizontal swimming displaces the crinoid, oral surface foremost, at a mean speed of 6.8 cm/s. Horizontal swimming is achieved by differential arm extension. Behavioral adaptations make use of ambient currents to augment displacement. Swimming mechanics are based on sequential repetition of arm strokes made approximately simultaneously by three coordinated groups of arms, verified experimentally by selective arm removal. The Reynolds number while swimming is calculated to be 8112, with a drag coefficient of 0.0148. Swimming occurs in short, repeatable bursts of 10–30 s. Continuous swimming beyond 4 min provokes a refractory period lasting 5–17 min during which individuals are incapable of swimming. Spontaneous swimming was never observed in situ nor in aquaria, but was elicited by mechanical stimulation or contact with potential predators. Trials with 17 cooccurring invertebrate species of diverse feeding modes show that swimming is provoked by opportunistic carnivores, notably asteroids. Swimming is an escape response against potential predators. Crawling is the primary means of moving from place to place. Crawling is induced by directional currents and by intraspecific contact. Spacing out of individuals within an aggregation may be accomplished by crawling following agonistic contact behaviour. Functional regionalization of the arms is discussed in relation to autotomy and predation.
Anaerobiosis and organ-specific regulation of glycolysis in a marine whelk
Authors: Storey Kenneth B. , Kelly David A. , Duncan John A. , Storey Janet M.
Published: August 2008

Changes in the levels of glycolytic intermediates, adenylates, phosphagen, and substrates and products of anaerobic metabolism were monitored over the initial hours of anaerobiosis in radular retractor muscle, foot muscle, and gill of the marine whelk Busycotypus canaliculatum. In all organs, changes in glycolytic intermediates upon exposure to N2-bubbled seawater indicated a biphasic response by glycolytic rate to anoxia: an immediate activation (within 30 min to 1 h) followed after 1–4 h by glycolytic rate depression. In both cases, regulatory control at phosphofructokinase and pyruvate kinase was indicated. The accumulation of anaerobic end products differed between the three organs. In radular retractor and gill, the ratio alanine succinate produced was 2:1 (but with higher amounts of both products in radular retractor), whereas in foot the ratio was 12.5:1. Foot muscle showed a large depletion of arginine phosphate reserves early in anoxia but little perturbation of adenylate pools, whereas gill and radular retractor showed a much lower net use of phosphagen but substantial depletion of organ ATP content. The data support several conclusions: (i) metabolic rate depression in the whelk is initiated within 1–2 h of anoxia exposure, (ii) mechanisms of metabolic depression override allosteric activating effects by phosphagen and adenylates on phosphofructokinase, and (iii) inhibition of flux through pyruvate kinase parallels the course of metabolic depression, not changes in carbon partitioning at the phosphoenolpyruvate branch point.
Effects of goose grazing on the quality of Scirpus americanus rhizomes
Authors: Bélanger L. , Giroux J.-F. , Bédard J.
Published: August 2008

We investigated whether repeated intensive grazing of rhizomes of three-square bulrush (Scirpus americanus) by greater snow geese (Chen caerulescens atlantica) staging in a tidal brackish marsh along the St. Lawrence River in Québec can induce changes in the nutritional value and structural characteristics of the rhizomes. We compared rhizomes growing on heavily used sites with those growing in ungrazed sites (exclosures) for 3 years. The belowground standing crop of S. americanus was greater in ungrazed than in grazed plots, but no difference was observed in the nutritional constituents (nitrogen and fiber) of rhizomes between the two types of plot. Moreover, S. americanus did not increase the deposition of phenolics (chemical defense) in its rhizomes following grazing. Our results lead us to conclude that goose grubbing decreases quantity without affecting quality of S. americanus rhizomes.
Life history, mating behavior, and courtship songs of the endemic Hawaiian Anomalochrysa maclachlani (Neuroptera: Chrysopidae)
Authors: Tauber Maurice J. , Tauber Catherine A. , Hoy Ronald R. , Tauber Paul J.
Published: August 2008

Although Anomalochrysa maclachlani shares many aspects of its life history and reproductive behavior with other green lacewings, it is atypical in several respects. (i) The preoviposition period is long, and it remains constant at temperatures from 21 through 26.7 °C. (ii) Fertility, which was 100% at 23.4 °C or lower, drops to 16.6% at 26.7 °C. (iii) Females oviposit clusters of about 25 unstalked eggs every 1–7 days, (iv) Both sexes produce loud clicking sounds during courtship; clicking frequently occurs in duet and is associated with anterior-directed flicks of the wings, (v) Females and males may mate repeatedly within several hours. The unusual features of A. maclachlani's reproductive behavior suggest a mode of sexual selection different from that in other chrysopids. Its loud courtship songs and those of other Hawaiian insects (Drosophila, crickets, plant hoppers) represent striking cases of parallel evolution among diverse groups of endemic fauna.
A comparison of the breeding ecology of a secondary cavity nesting bird, the Tree Swallow (Tachycineta bicolor), in nest boxes and natural cavities
Authors: Robertson Raleigh J. , Rendell Wallace B.
Published: August 2008

Several studies concerned with mate choice, reproductive performance, and life history strategies have been conducted with secondary cavity nesting birds breeding in nest boxes. Although the need for comparative studies has been recognized, populations breeding in nest boxes often have not been compared with those breeding in natural cavities. We compared the ecology of Tree Swallows breeding in nest boxes and natural cavities to determine if nest box populations of Tree Swallows are accurate models of natural populations. Two nest site characteristics, nest site dispersion and cavity height, were similar for birds in both nesting environments. Greater cavity entrance area at natural cavities resulted in increased interspecific competition in natural populations, involving larger competitors, more species, and a greater abundance of each species. Clutch size was smaller in natural cavities compared with nest boxes, likely because floor area was smaller in natural cavities. Fledging success did not differ between populations. Disproportionately more after-second-year females bred in nest boxes, and more second-year females bred in natural cavities, as estimated by a model of Tree Swallow survivorship. Tree Swallows settle at nest boxes before natural cavities in our study area, perhaps as a result of the greater potential for reproductive success and reduced interspecific competition in the nest boxes as opposed to natural cavities. For some aspects of the ecology of secondary cavity nesters, nest boxes do not provide an accurate representation of natural populations. Therefore, evolutionary interpretations of nest box studies should be compared with observations of birds in natural environments.
The prelarva of Alycus roseus Koch (Bimichaeliidae: Acariformes: Acari)
Authors: Kethley J.
Published: August 2008

The prelarva of Alycus roseus Koch is described. It is the only prelarva known for species of the early derivative acariform family Bimichaeliidae. The prelarva is highly regressed, with the palps and legs fused to the ventral surface. The record is also the first for A. roseus in North America.
Thermal hysteresis activity in the skin of the cunner, Tautogolabrus adspersus
Authors: Valerio P. F. , Kao M. H. , Fletcher G. L.
Published: August 2008

Previous studies have shown that cunners, Tautogolabrus adspersus, remain inshore in marine waters around Newfoundland during the winter months, but are in a state of metabolic torpor, apparently surviving by undercooling without freezing. The present study reports the discovery of measurable levels of thermal hysteresis activity in aqueous extracts of winter cunner skin, but not in the blood plasma. The occurrence of a compound with thermal hysteresis activity indicates the presence of antifreeze polypeptides in the Labridae. This is of significant interest, since this family is mostly tropical in distribution, and has likely invaded northern waters in relatively recent times. The functional significance of skin thermal hysteresis activity is discussed in relation to the protective role of antifreeze compounds.
In vitro cultivation of the vascular phase of Sarcocystis hirsuta (Apicomplexa)
Authors: Cawthorn R. J. , Markham R. J. F. , Hitt N. D. , Despres D.
Published: August 2008

Sporozoites of Sarcocystis hirsuta (Apicomplexa), although they also penetrated into bovine monocytes, developed to the schizogonous phase only in bovine pulmonary artery endothelial cells. Schizonts were evident beginning 14 days after sporozoite inoculation (DAI) and persisted to 62 DAI, when experiments were terminated. Merozoites and schizonts were most numerous 35–53 DAI. The number of schizogonous generations was not determined. In vitro cultivation of schizonts of S. hirsuta will facilitate comparisons with development of S. cruzi, and this will aid elucidation of mechanisms of pathogenesis and immunologic responses caused by these two important cattle parasites.
The diet of herring gulls during the nesting period in Canadian waters of the Great Lakes
Authors: Fox G. A. , Allan L. J. , Weseloh D. V. , Mineau P.
Published: August 2008

We report the content of 132 boli and 2000 pellets regurgitated by adults and 1749 boli regurgitated for or by chicks in 25 herring gull (Larus argentatus) colonies in Lakes Ontario, Erie, Huron and Superior, between mid-April and mid-July, 1977–1983. Fish were the predominant food in all four lakes. Although 11 families of fish and a minimum of 16 species were identified, 80% of the fish were of two exotic species, the alewife (Alosa pseudoharengus) and the rainbow smelt (Osmerus mordax). The dietary importance of these two fish species reflected their relative abundance within a lake. In addition, representatives of eight orders of insects and 11 families of birds were identified. In the one colony where diets of birds of known sex were quantified, male and female gulls fed on different proportions of alewife and smelt, suggesting the sexes have different foraging strategies. Although some food was scavenged, most was obtained alive. Dietary differences existed between colonies and between lakes, both within and between years. We suggest that diet, contaminant burden, and population size of Great Lakes herring gulls will be affected by fisheries policies which alter the predator–prey dynamics of this exotic-dominated ecosystem.
Interactions between asymmetric brow tines in caribou and reindeer antlers
Authors: Goss Richard J.
Published: August 2008

The brow tines of caribou and reindeer (Rangifer tarandus) are typically asymmetric. One, usually the left, is branched or laterally compressed into a "shovel," the other remaining as an unbranched spike. Less commonly, both tines may be simple or both enlarged into the "double shovel" configuration. Analysis of 273 specimens confirmed the preponderance of left dominance in brow tines. Even when both are enlarged, the left one tends to be bigger. Bez tines arise more proximally on the antler when the brow tine is small or absent. Brow tines tend to converge medially. When one is larger than the other, the angle of growth with respect to the midline of the head averages 13.03° for the dominant tine and 6.22° for the smaller one. In double shovels, the brow tines are more parallel, averaging 7.31° from the midline. Sometimes the two tines grow above and below each other. These findings suggest that brow tines adapt their length and direction of elongation so as to avoid contact.
The effects of pollen availability on development time in the bumble bee Bombus terricola K. (Hymenoptera: Apidae)
Authors: Sutcliffe G. H. , Plowright R. C.
Published: August 2008

Captive colonies of Bombus terricola Kirby received pollen for 8, 14, or 24 h/day. The effects of the treatment demonstrated experimentally the influence of larval nutrition on development time. The duration of the cocoon stage was positively related to both adult body size and pollen availability. The duration of the larval stage varied in a more complex way: within each treatment, duration of the larval stage was positively related to adult body size, but between the treatments, and for each of the three castes, pollen deprivation tended to lengthen the larval stage. These results reconcile divergent findings in the literature.
Cytomorphology of the pedal aperture glands of Mya arenaria L. (Mollusca, Bivalvia)
Authors: Norenburg Jon L. , Ferraris Joan D.
Published: August 2008

A glandular cushion, called the pedal aperture gland in this paper, lies adjacent and internal to each of the two mantle margins composing the pedal aperture of the soft-shelled clam Mya arenaria. Two types of glandular cells are found in the glands. The principal type (bacillary mucous cell) manufactures secretory vesicles that contain discrete protein-rich fibers in a matrix of glycoprotein. The second type (mucous goblet cell) produces sulfated and nonsulfated mucosubstances. The glands function in the formation of pseudofeces from particulate material, especially burrow sediments that enter the mantle cavity through the pedal aperture. Their possible phylogenetic relationship to similar glands in other bivalves is discussed briefly.
Évolution au cours de l'hivernage de la répartition spatiale et de l'habitat de la Sarcelle d'hiver (Anas c. crecca) sur une aire de repos de la côte atlantique française
Authors: Génard Michel , Fleury Alain
Published: August 2008

Teals wintering in a resting area of the French Atlantic coast, the Ornithological Park of the Teich (Gironde), were localized and counted during diurnal censuses distributed regularly over the wintering season 1985–1986. Environmental descriptors were measured simultaneously by sampling and consisted in (i) variables with a time component in the areas occupied by teals and (ii) variables with a space component in the whole park area. Multivariate analysis (correspondence analysis, classification, discriminant analysis) were performed on census and measure data. Different distribution patterns of teals were defined, corresponding to successive periods of the wintering season. These changes may be due to variations in salinity, wind direction, intensity of disturbance (caused by men or predators), and also to a decrease in teal gregariousness and to changes in feeding behavior during wintering. Habitats selected by teals were defined for each period. Moist rush areas, close to shallow ponds with weakly sloped shores, were selected before mid December. Ponds of average depth with average-sloped shores, bordered with meadows or woods, and dry rush areas were then occupied. These habitat changes were interpreted.
Sélection des proies par quatre espèces d'oiseaux limicoles (Charadrii) de passage dans l'estuaire du Saint-Laurent lors de la migration vers le sud
Authors: Michaud Guy , Ferron J.
Published: August 2008

The diet of four shorebird species, the Black-bellied Plover (Pluvialis squatarola), Semipalmated Plover (Charadrius semipalmatus), Lesser Yellowlegs (Tringa flavipes), and Semipalmated Sandpiper (Calidris pusilla), was studied on an intertidal mudflat during their southward migration. Mollusks dominate the invertebrate fauna in the feeding area, representing 95% of the organisms in terms of number and biomass. The predatory shorebirds appeared to forage selectively on polychaetes and crustaceans, which represent only 5% of the benthic invertebrates in the feeding area. Lesser Yellowlegs eat nearly exclusively crustaceans. The other three predators feed mainly on Nereis virens and all three select groups of worms that differ significantly by their size, the larger predators consuming the biggest prey. Despite the simultaneous presence of the four predators on the feeding area, they seem to share the resources without overt interspecific competition.
Effet du stress de la manipulation sur le comportement du Carouge à épaulettes (Agelaius phoeniceus)
Authors: Brunet Richard , Cyr André
Published: August 2008

We studied the behavioural effect of increasing the frequency of handling in Red-winged Blackbird (Agelaius phoeniceus), a species that is weight sensitive to captivity. Manipulations consisted in weighing groups of birds every 1, 3, 6, and 9 days, and measuring their food consumption, activity level, and behaviour. Results show that the more frequently the birds are manipulated, the less active they become, the less food they consume, and the more weight they lose. On the day of the manipulation, all birds reacted similarly, regardless of the frequency of manipulation for their group. They remained inactive for extended periods of time after being manipulated, probably because of the stress induced. The next day, they fed as much or more than the day before the manipulation. The longer the time interval between manipulations, the better their weight recovery. If stresses were at too close a time interval from one another, the birds constantly lost weight. Spacing manipulations, whatever they are, would be a reasonable solution to avoid the expression of disturbed behaviours and the loss of weight in captive wild birds used in behavioral studies.
Disease caused by Nemesis robusta (van Beneden, 1851) (Eudactylinidae: Siphonostomatoida: Copepoda) infections on gill filaments of thresher sharks (Alopias vulpinus (Bonnaterre, 1758)), with notes on parasite ecology and life history
Authors: Benz George W. , Adamson Sidonie Anne Margaret
Published: August 2008

Thresher shark gill filaments infected with the copepod Nemesis robusta exhibited a diseased state. Tissue erosion seemingly associated with the rasping effects of various copepod appendages and feeding activity was evident. Host response to parasites was grossly seen as swollen and blanched zones about infected regions. Histologically the host response consisted of proliferated epithelial and underlying connective tissue layers surrounding the efferent branchial arterioles at the gill filaments' free distal tips. Copepod attachment close to secondary lamellae was associated with proliferation of both respiratory epithelium and epithelium between the secondary lamellae. Tissue proliferation partially or completely occluded interlamellar water channels and probably compromised respiratory efficiency by blocking water passage between secondary lamellae. The abnormal thickness of affected secondary lamellae probably further reduced respiratory ion exchange.
Infection of whitefish (Coregonus lavaretus L. s.l.) by Triaenophorus crassus Forel (Cestoda: Pseudophyllidea): a case study in parasite control
Authors: Amundsen Per-Arne , Kristoffersen Roar
Published: August 2008

A case study of Triaenophorus crassus control in two sympatric whitefish populations was carried out in Stuorajavri, northern Norway. The densities of whitefish and pike were markedly reduced by an intensive fishing programme and during the 6 years of investigation, a dramatic decline in T. crassus infection of whitefish was observed. The mechanisms involved in parasite control were elucidated by studying the differences in infestation over time between T. crassus and a related cestode, Diphyllobothrium ditremum, in the two whitefish populations. Reduction in population density of the final host, pike, is suggested as being the key factor in control of T. crassus. Exploitation and reduction of whitefish population density contributed to decreased infection in one of the whitefish populations by influencing its acquisition of parasites via a change in its food selection.
Skin folds in the gekkonid lizard genus Rhacodactylus: a natural test of the damage limitation hypothesis of mite pocket function
Authors: Bauer Aaron M. , Russell Anthony P. , Dollahon Norman R.
Published: August 2008

The hypothesis that lizard mite pockets have evolved as a host response to limit damage by ectoparasites is tested. Evidence from the New Caledonian geckos of the genus Rhacodactylus does not support the hypothesis. Putative pockets in popliteal position are present in all taxa examined, but are infested by trombiculid chiggers only in Rhacodactylus auriculatus, a partially terrestrial species. Tissue damage results from the formation of a stylostome within the host pocket. No mechanisms for host amelioration of parasite effect are evident. At least in Rhacodactylus, chiggers appear to facultatively exploit skin folds or pockets, which may have evolved and been maintained as a result of selective forces unrelated to ectoparasite damage limitation.
Habitat segregation among the age groups of Gasterosteus aculeatus (Pisces: Gasterosteidae) in the middle St. Lawrence estuary, Canada
Authors: Picard Jr. Paul , Dodson Julian J. , FitzGerald Gérard J.
Published: August 2008

Previous studies of migratory populations of sticklebacks (Pisces: Gasterosteidae) have been exclusively limited to their biology on the spawning grounds during the spring breeding season. In 1985 and 1986, we studied the ecology of the threespine stickleback (Gasterosteus aculeatus) in three subhabitats of the middle St. Lawrence estuary before, during, and after the breeding season: (i) the open waters of the estuary, (ii) a series of intertidal salt marsh pools, and (iii) two tidal rivers (Rivière des Vases and Rivière Trois-Pistoles). In spring, our catch data in the various subhabitats showed that adults moved from the open waters of the estuary towards the tidal rivers and tide pools. Catches of adults in all subhabitats subsequently declined, whereas the young of the year (age 0+) became increasingly abundant. In this area, G. aculeatus live for 2 years and are physiologically capable of breeding during their first summer as adults. However, we found age-related differences in habitat use between the two adult year classes. Age 1+ fish were never more abundant than age 2+ fish in Rivière des Vases, in the tide pools, and in the open waters of the estuary, whereas age 1+ fish were more abundant than age 2+ fish in Rivière Trois-Pistoles. Throughout the breeding season, gonadosomatic indices of female G. aculeatus were the same for the two age groups. Total lengths of age 0+ fish captured in the various subhabitats suggest that the major spawning period is limited to May and June. Age 0+ fish do not leave the tide pools for the open waters of the estuary before having attained a certain minimum size.
Serotonin, octopamine, and the clinging behavior induced by the parasite Polymorphus paradoxus (Acanthocephala) in Gammarus lacustris (Crustacea)
Authors: Helluy Simone , Holmes John C.
Published: August 2008

Gammarus lacustris infected with cystacanths of Polymorphus paradoxus display an abnormal behavior. They respond to disturbance by swimming to the surface and clinging to a solid object (W. M. Bethel and J. C. Holmes. 1973. J. Parasitol. 59: 945–956). Uninfected gammarids injected with serotonin (1–20 μg/50 mg) but not other neurotransmitters also responded to mechanical stimulation by clinging, but the response lasted for a shorter time than in infected gammarids. Octopamine suppressed the clinging response in infected gammarids for several hours. The results suggest that cystacanths of P. paradoxus modulate the behavior of gammarids through the alteration of neural activity in some serotonin-sensitive or serotonergic central pathway, probably one involved in precopulatory clinging in male amphipods.