bluuebunny/crossref_metadata_2025 huggingface dataset:
Maneuverability of four species of coral-reef fish that differ in body and pectoral-fin morphology
Authors: Gerstner Cynthia L
Published: April 2011

Maneuverability was measured during feeding and agonistic interactions in four sympatric species of coral-reef fish differing in body and pectoral-fin morphology: foureye butterflyfish, Chaetodon capistratus (deep body, low aspect ratio (AR) fins), beaugregory damselfish, Stegastes leucostictus (medium-depth body, low AR fins), ocean surgeonfish, Acanthurus bahanieusis (medium-depth body, high AR fins), and bluehead wrasse, Thalassoma bifasciatum (slender body, high AR fins). Damselfish turned faster, using median- and paired-fin propulsion, than either surgeonfish or wrasse, but their performance did not differ from that of butterflyfish during maneuvering behaviours common to all species. Each of these pairs had similar pectoral-fin morphology but exhibited an intermediate body morphology. This suggests that pectoral-fin morphology was more important in determining performance within maneuvers, and therefore butterflyfish and damselfish were superior maneuverers to surgeonfish or wrasse. To turn faster, fish shifted from median- and paired-fin propulsion to body and caudal-fin propulsion; however, turning radii were unaffected. Pectoral-fin morphology also determined the use of maneuvering behaviours within gaits that are used by fish to fractionate their locomotor-performance range. In general, morphological differences among species were correlated more often with behavioral differences than with locomotor performance. Fish differing in body and fin morphology express different gaits, and within these gaits, they express different behaviours; however, overall performance may converge.
The ultrastructure of the spermatozoa of the worm lizard Amphisbaena alba (Squamata, Amphisbaenidae) and the phylogenetic relationships of amphisbaenians
Authors: Teixeira Ruscaia D , Colli Guarino R , Báo Sônia N
Published: April 2011

We describe the ultrastructure of epididymal spermatozoa of Amphisbaena alba and make comparisons with spermatozoa of other squamates. The mature spermatozoon of A. alba is filiform and characterized by the following features: the acrosome is depressed in transverse section; the perforatorial base plate is absent; the perforatorial tip is pointed; the perforatorium is single; the epinuclear lucent zone is well developed; the midpiece is moderately long; the mitochondria are columnar, forming regular circlets interrupted by dense bodies in transverse section; the dense bodies are solid, arranged in regular rings and linear series; the nuclear shoulders are rounded; the nucleus is elongate; the endonuclear canal is absent; fibers 3 and 8 are enlarged; multilaminar membranes are absent; and the fibrous sheath is in the midpiece. A phylogenetic analysis of squamates using spermatozoon-ultrastructure characters resulted in 2415 equally parsimonious, largely unresolved trees. The use of a constraint tree derived from gross anatomical characters suggested that the Amphisbaenia is the sister-group of the Autarchoglossa. We conclude that to improve the resolution of phylogenetic hypotheses derived from spermatozoon-ultrastructure characters, the number of characters ought to be increased, and more investigations are necessary to ascertain the degree of intrafamilial variability.
Song of the snow bunting (Plectrophenax nivalis) in areas with and without sympatric passerines
Authors: Espmark Yngve
Published: April 2011

The acoustic-competition hypothesis predicts that in areas with low species diversity, bird song will vary more from one individual to another and the song of each individual will be less complex than those of conspecifics in areas with more species. The aim of this study was to investigate whether this prediction also applies to the snow bunting (Plectrophenax nivalis), which is the only passerine species that breeds regularly in Svalbard, whereas on the Scandinavian mainland it breeds sympatrically with several other species. Songs of 22 and 19 male snow buntings from study areas at Longyearbyen in Svalbard and on the Varanger peninsula in northern Norway, respectively, were analysed with respect to the number and type of syllables and motifs, syllable and intersong diversity, song length, maximum, minimum, and range of frequency, and sharing of song features between individuals. None of the variables differed significantly between the two areas with respect to song variation between individuals. It is suggested that this is related primarily to the migratory and vagrant behaviour of the species, which is thought to entail a considerable annual turnover in the breeding populations in relation to the geographical origin of the birds. Songs were significantly simpler in Svalbard than on the mainland only when complexity was measured as syllable diversity. When it was measured in terms of diversity of song motifs, an opposite, although insignificant, trend was found. The reason for this contradictory tendency is discussed in relation to the problem of defining complexity and choosing relevant variables for assessing song complexity. Individuals in both areas commonly shared syllables, but rarely motifs and song types. The snow buntings in Svalbard shared song features to about the same extent as the birds on the mainland.
Sociobiology of the myrmecophagous sloth bear in Nepal
Authors: Joshi Anup R , Smith James LD , Garshelis David L
Published: April 2011

Ursids have adapted to environments ranging from the tropics to the arctic, and although the family is noted for its omnivory, some species have specialized food habits. The sloth bear (Melursus ursinus) has specialized on insect prey, particularly termites and ants, and exhibits some characteristics and behaviors that are common among myrmecophagous mammals. We examined whether myrmecophagy has affected its sociobiology. During 1990-1994 we studied a high-density population of sloth bears in Royal Chitwan National Park, Nepal. We found extensive seasonal overlap among home ranges of adults of the same sex (>50%) and between subadults and adults of both sexes (>70%). Moreover, overlap zones between adjacent ranges were used in proportion to their area. This, and observations of unrelated bears feeding or traveling in proximity to one another (not at concentrated food sources), suggested a high degree of mutual tolerance in this population. However, subadults and females with young may have temporally avoided other bears by limiting their activity to daylight hours. Predators (which were chiefly nocturnal) may also have affected the activity patterns of these (the most vulnerable) bears, and were probably responsible for the females' habit of giving birth in an underground den, fasting for several weeks so as not to leave cubs unattended in the den, and carrying the cubs on their back for 6-7 months after leaving the den. The young left their mother at 1.5 or 2.5 years old (this varied by family) and remained together and (or) later rejoined a sibling or another subadult, possibly to form a coalition against either predators or older bears. We documented few mortalities and no permanent juvenile dispersal in this study, but we also found few subadults in our study area, which indicates undetected mortality or dispersal. We cannot discount the possibility that some aspects of the sociobiology of sloth bears (e.g., cub-carrying, mutual tolerance) are related to myrmecophagy, but the social system and life-history traits of this species seem to fit well within the range observed among other ursids.
Forage selection by elk in habitats common to the French River - Burwash region of Ontario
Authors: Jost M A , Hamr J , Filion I , Mallory F F
Published: April 2011

A study of two herds of Rocky Mountain elk (Cervus elaphus nelsoni) introduced into the French River - Burwash regions of Ontario in the 1940s was undertaken to assess forage selection and availability. Studies in western North America have shown that the diets of elk vary seasonally, spatially, and in response to forage availability, palatability, plant phenology, plant species diversity, and habitat type. These studies have concluded that grasses, browse, and forbs were preferred forage items and that indigenous grass was used most. In an attempt to obtain a more detailed understanding of forage use in relation to habitat type, selection and availability of forage in ridge, mixed-forest, and grassland habitats was analyzed by tracking elk during a 2-year period. More than 1000 forage occasions were recorded from approximately 60 animals. It was hypothesized that Rocky Mountain elk in the French River - Burwash region would select forage species similar to those found in western North America. The results of this study support the following conclusions: (i) elk in the French River - Burwash regions of Ontario use ridge, mixed-forest, and grassland habitats for foraging; (ii) most forage consumed by elk in this region is woody species, grasses, or forbs, common in mixed-forest habitats; (iii) open grasslands increased forage diversity minimally and appeared to be the least important for foraging; (iv) uncultivated grasslands dominated by Old World agricultural gaminoid species, such as timothy (Phleum pratense), quack grass (Elymus repens), wire grass (Poa compressa), and redtop (Agrostis gigantea), or by indigenous graminoid species, such as white-grained mountain rice (Oryzopsis asperifolia), Canada blue joint (Calamagrostis canadensis), poverty oat grass (Danthonia spicata), and (or) fringed brome grass (Bromus ciliatus), may provide little nutritional support for elk in this region; (v) habitats containing large amounts of willow (Salix spp.), red maple (Acer rubrum), and common hairgrass (Deschampsia flexuosa) provide a significant forage base for elk in the Great Lakes - St. Lawrence ectone; and (vi) relocated Rocky Mountain elk in Ontario use forage classes similar to those utilized by elk in western North America; however, woody browse is the dominant forage used.
Citral, an inhibitor of retinoic acid synthesis, modifies pattern formation during limb regeneration in the axolotlAmbystoma mexicanum
Authors: Scadding Steven R
Published: April 2011

While the effects of exogenous retinoids on amphibian limb regeneration have been studied extensively, the role of endogenous retinoids is not clear. Hence, I wished to investigate the role of endogenous retinoic acid during axolotl limb regeneration. Citral is a known inhibitor of retinoic acid synthesis. Thus, I treated regenerating limbs of the larval axolotl Ambystoma mexicanum with citral. The result of this inhibition of retinoic acid synthesis was that limb regeneration became extremely irregular and hypomorphic, with serious pattern defects, or was inhibited altogether. I conclude that endogenous retinoic acid plays an important role in pattern formation during limb regeneration.
The effect of age and experience on the reproductive performance and prenatal expenditure of resources in female fallow deer (Dama dama)
Authors: San José C , Braza F , Aragón S
Published: April 2011

In this paper we tested whether prenatal expenditure of resources in fallow deer (Dama dama) is affected by the age and reproductive experience of mothers. The study was carried out on the wild fallow deer population in Doñana National Park in southwestern Spain. Between 1985 and 1996 a total of 60 different females were monitored by direct observation during the fawning season. The exact age of 22 of these females was known, and 59 fawns born of these females were captured. The mother's age had more influence on the fawn's birth mass than the mother's experience did. Fallow deer fawns born of adult multiparous mothers (5-8 years old) were heavier than fawns born of young multiparous mothers (3-4 years old), whereas birth masses of fawns born of primiparous mothers (2-3 years) and young multiparous mothers showed no significant difference. Fawns were born earlier in the breeding season as the mother's age increased. The trade-off required between resources allocated to reproduction and resources available for growth and maintenance may limit reproduction and the possibility of increasing prenatal expenditure by both young primiparous and young multiparous female fallow deer. Sexual dimorphism in birth mass was detected, males being heavier than females, independently of the age and parity of the mothers. This confirms the finding that fallow deer mothers are selected to expend more resources on their male offspring.
A temporal shift in Steller's jay predation on bird eggs
Authors: Sieving Kathryn E , Willson Mary F
Published: April 2011

Artificial-nest experiments conducted near Juneau, Alaska, indicated that Steller's jays (Cyanocitta stelleri) may undergo a marked shift in foraging pattern and possibly nest-predation behavior triggered by fledging of their own chicks. In an early-June sampling of predation on artificial nests containing quail eggs, egg losses and jay activity levels were significantly higher in forest adjacent to human-created edge than in undisturbed interior forest. In a late-June sampling, however, nest predation near edges was significantly reduced, and this was correlated with a drop in jay activity (detected via predator censuses and remote-controlled camera stations baited with artificial nests). Steller's jays in natural nests monitored during the study fledged their chicks between the two samplings, which suggests that quail eggs were an important food for jays during their nestling period (early June) but not after (late June). Nests in the two plots in interior forest, where jays were rarely detected, had consistently low nest predation rates in both samplings. These data support the hypothesis that during their nestling period, adult Steller's jays in southeast Alaska may prey intensively on the contents of other birds' nests in the vicinity of their own nests, but that fledging of jay chicks abruptly changes foraging patterns, including possibly reducing nest-predation behavior. Given the short breeding season in southeast Alaska, it is likely that during the postfledging period, jay families concentrate on obtaining foods (e.g., conifer seeds) that are more important for over-winter survival of the juveniles than nest contents, which decrease rapidly in abundance during July.
In-air and underwater hearing sensitivity of a northern elephant seal (Mirounga angustirostris)
Authors: Kastak D , Schusterman R J
Published: April 2011

In-air and underwater sound detection thresholds were obtained for a female northern elephant seal (Mirounga angustirostris). Hearing sensitivity in air was generally poor, but was best for frequencies between 3.2 and 15 kHz, and showed greatest sensitivity at 6.3 kHz (43 dB re: 20 µPa). The upper frequency limit in air was approximately 20 kHz. The underwater audiogram is similar to those obtained from other phocids in that sensitivity was best between 3.2 and 45 kHz, with greatest sensitivity at 6.4 kHz (58 dB re: 1 µPa) and an upper frequency cutoff of approximately 55 kHz. The elephant seal was more sensitive to low frequencies (<1 kHz) than other pinnipeds tested. Thresholds obtained in water were lower than those obtained in air (19 dB in terms of sound pressure, 52 dB in terms of sound intensity), indicating that the elephant seal is adapted for underwater hearing. The outer and middle ears of the elephant seal are modified relative to those of other phocids. These modifications are probably needed to cope with extreme static pressures related to deep diving, and are likely to confer relatively good auditory sensitivity under water.
The effects of dietary protein content on growth and maturation in deer mice
Authors: McAdam Andrew G , Millar John S
Published: April 2011

Growth and female maturation appear to be limited by the availability of dietary protein in natural populations of deer mice (Peromyscus maniculatus borealis) in the Kananaskis Valley, Alberta. We examined the effects of dietary protein content on nestling growth rates and sexual maturation of female deer mice in two laboratory experiments. In the first, mice whose mothers were fed a low-protein mixture of sunflower seeds and oats (14% protein) exhibited slow growth prior to weaning and those fed high-protein cat food (30% protein) postweaning showed compensatory growth. Preweaning but not postweaning diet quality affected the proportion of females who were sexually mature at 42 days of age. Therefore, while deficient nestling growth can be compensated for, the effects of a low-quality maternal diet during lactation may have lasting effects on the maturation of female offspring. In the second experiment, mice raised on isocaloric diets of 14, 20, and 30% protein did not differ in growth as nestlings or juveniles. Differences among the three diets in the proportion of mature females at 42 days did not correspond to dietary protein levels as predicted. Dietary protein content from 14 to 30% appear to be sufficient for juvenile mice raised in captivity.
Internal female reproductive anatomy and genital interactions during copula in the yellow dung fly,Scathophaga stercoraria(Diptera: Scathophagidae)
Authors: Hosken D J , Meyer E P , Ward P I
Published: April 2011

Insect genitalia have been extensively studied for taxonomic purposes, but functional anatomy has rarely been examined. We report here on the detailed internal anatomy of the reproductive tract of female yellow dung flies (Scathophaga stercoraria) and the mechanics of copula and sperm transfer. Female dung flies have paired accessory glands, three spermathecae (one singlet and one doublet), each with its own narrow duct, a large muscular bursa copulatrix, which is met by the common oviduct dorso-anteriorly, and paired lateral oviducts and ovaries. The bursa is lined internally with a thick cuticle. During copula and while ejaculating, the male aligns the gonopore with the spermathecal duct entrances to the bursa and pinches the female's abdomen at approximately this point. Sperm packing in the spermathecae appears quite orderly, and structurally the sperm appear typical of many insects. Aedeagus withdrawal appears to remove some bursal sperm. The results are discussed in relation to other Diptera.
Comparing bird assemblages in successional black spruce stands originating from fire and logging
Authors: Imbeau Louis , Savard Jean-Pierre L , Gagnon Réjean
Published: April 2011

Comparisons of the effects of logging and fire as disturbance agents on the composition of bird assemblages in boreal ecosystems are still lacking or are limited to the short-term impacts of clear-cutting. In Quebec, where the boreal forest is largely dominated by black spruce (Picea mariana (Mill.) B.S.P.) stands, we surveyed 140 point-count stations in 3 postlogging and 4 postfire development stages determined according to the height of the regenerating spruce trees. Species richness did not vary among forest development stages, but bird abundance was higher in recent clearcuts. Recently disturbed areas were characterized by open-land bird assemblages dominated by Neotropical migrants, which reached their highest abundance in clearcuts. Moreover, logged stands were distinguished from burned sites by the absence of cavity-nesting birds. Forest-bird assemblages reestablished themselves as soon as young spruces reached the sapling stage. However, the Black-backed Woodpecker (Picoides arcticus), Three-toed Woodpecker (Picoides tridactylus), and Brown Creeper (Certhia americana) were restricted to mature stands or recent burns and are thus likely to be negatively affected by modern forestry, which involves fire suppression and short logging rotations. We suggest that retention of larger areas of continuous mature forest might be essential to maintain these species in managed regions.
Phenotypic plasticity in the labral fan of simuliid larvae (Diptera): effect of seston load on primary-ray number
Authors: Lucas Peter , Hunter Fiona F
Published: April 2011

The number of primary rays in the labral fan of filter-feeding black fly (Diptera: Simuliidae) larvae has been used by some authors to aid in species identification. We examined the number of primary labral fan rays in field-collected last-instar larvae of Simulium rostratum and Simulium decorum. Significant inter- and intra-specific differences were found both spatially and temporally. Simulium rostratum and S. decorum larvae were also reared to last instar (from eggs or first- or second-instar larvae) under three feeding regimes to test the effect of seston load on the number of primary labral fan rays. In both species the fan-ray number decreased when the food supply was increased. We conclude that the primary fan ray number should be used cautiously in species diagnosis because it is a phenotypically plastic trait that varies with seston load. A potential feedback mechanism to explain the observed differences in fan-ray number is hypothesised.
Virulence of the cestode Schistocephalus solidus and reproduction in infected threespine stickleback, Gasterosteus aculeatus
Authors: Heins David C , Singer Scarlet S , Baker John A
Published: April 2011

We investigated the relationship between reproduction in the threespine stickleback (Gasterosteus aculeatus) and parasitism by plerocercoids of the cestode Schistocephalus solidus in Walby Lake, Alaska, by quantifying stickleback reproduction and parasite infection using 1655 fish from four samples collected in 1990-1996. Stickleback in Walby Lake largely spawned during May and June as 2-year-olds in the second spring-summer after hatching, as was the case with other stickleback populations we studied in south-central Alaska. Contrary to an earlier hypothesis that S. solidus has been selected to delay its deleterious effects on threespine stickleback, i.e., limit its infection levels, until after the stickleback have reproduced, substantial levels of parasitic infection co-occurred with the stickleback reproductive period. Chi-squared analyses of individual samples suggested that in May, infected females were as capable of producing clutches of eggs as uninfected females but in June, S. solidus inhibited clutch production. An overall analysis, however, failed to support the hypothesis that the effect of S. solidus on clutch production differed between early and late periods of the spawning season. We concluded that S. solidus inhibits the ability of female stickleback in Walby Lake to produce a clutch, and that there was no differential effect on clutch production with season. Nonetheless, 77% of all infected females produced clutches. These results contrast with those of one study in which it was found only 9% of infected females became gravid (ripe) and another report that 23% of infected females were able to mature. We offer hypotheses for the co-occurrence of stickleback reproduction and substantial parasitism at the population level and for the ability of a large proportion of infected females to produce clutches. Our results suggest that the host-parasite relationship is more complex than was previously realized.
The winter immunoenhancement hypothesis: associations among immunity, density, and survival in prairie vole (Microtus ochrogaster) populations
Authors: Sinclair J A , Lochmiller R L
Published: April 2011

Seasonal variations in photoperiod, temperature, and population density have been shown to modulate immune responsiveness of animals in laboratory studies. To examine these associations under natural conditions, we monitored 3 populations of prairie voles (Microtus ochrogaster) for temporal variations in selected immunological parameters, population density, and survival rate from winter 1996 to spring 1997. Spontaneous and cytokine-stimulated T-cell proliferative responsiveness of prairie voles peaked in winter and declined in spring. Relative organ mass, hemolytic-complement activity, and in vivo hypersensitivity responses varied temporally but showed no clear seasonal trend. The population density and survival rate of all 3 prairie vole populations varied temporally and correlated with measures of immunity. Multiple regression analysis indicated that the model containing relative spleen mass, cytokine-stimulated T-cell proliferation, and in vivo hypersensitivity explained a significant amount of variability in population density, while cytokine-stimulated T-cell proliferation and relative thymus mass explained a significant amount of variability in survival rate. The results suggest that seasonal environmental changes can enhance immune responsiveness of a host and may counteract the immunoenhancing effects of photoperiod in wild populations of prairie voles. Our results also suggest that there is an association between immune function and demography in wild populations.
Winter survivorship of hatchling painted turtles (Chrysemys picta) in Michigan
Authors: Nagle Roy D , Kinney Owen M , Congdon Justin D , Beck Christopher W
Published: April 2011

Hatchling painted turtles (Chrysemys picta) often exhibit delayed emergence by remaining in shallow sub- terranean nest cavities throughout winter. As a result, those at northern latitudes are sometimes exposed to lethal subzero temperatures. Our field study compared survivorship of hatchling C. picta during a winter in which low subzero temperatures coincided with the absence of insulating snow cover (1995-1996) with survivorship during the following three winters (1996-1997, 1997-1998, and 1998-1999), which were characterized by more moderate conditions. Ambient-air and soil temperatures were monitored at a weather station located within ~1 km of all nests. During the first winter of our study (1995-1996), minimum ambient-air temperature reached -25.6°C on 2 February, concomitantly with the complete absence of snow cover, and soil temperatures fell to between -7 and -9°C. Resultant over-winter hatchling mortality was 45%. Because some hatchlings survived temperatures well below the lethal limits described for freeze tolerance (-1 to -4°C), it is likely that hatchlings in Michigan sometimes survive by supercooling. During the following three winters, soil temperatures remained above -2°C, except during brief periods when they fell to -4°C in the absence of snow cover. Over-winter hatchling mortality was <3% during each of these last 3 years. Our study highlights the importance of insulating snow cover to survival of hatchling C. picta. Air temperature and snowfall data from southeastern Michigan over the past 33 years indicate that conditions associated with substantial winter mortality occurred in 3 out of 33 years (9.1%). We demonstrate that the impact of substantial over-winter mortality on hatchling recruitment is dependent on nest survivorship during the preceding nesting season.
Shell shape, dysodont tooth morphology, and hinge-ligament thickness in the bay mussel Mytilus trossulus correlate with wave exposure
Authors: Akester Robert J , Martel André L
Published: April 2011

We examined the shell morphology of the bay mussel Mytilus trossulus (Gould) at six locations with various levels of wave exposure in Barkley Sound on the west coast of Vancouver Island, British Columbia, Canada. Young adult M. trossulus (29-35 mm shell length) collected from wave-exposed sites displayed striking differences in shell morphology from M. trossulus from sheltered sites. Mytilus trossulus from wave-exposed habitats had a lower shell height / shell width ratio and a thicker shell; they also had higher, more robust dysodont teeth, as well as a thicker hinge ligament. Examination of juveniles (12-14 mm shell length) collected from a wave-exposed shore and a sheltered shore separated by only a few hundred metres displayed similar differences in shell morphology and ligament thickness. These observations suggest that wave exposure is the cause of the observed differences in shell morphology and ligament thickness in M. trossulus. This is the first report of a correlation between wave exposure and morphology of the dysodont teeth and ligament in a bivalve. We discuss potential selective pressures that may favor characteristics of wave-exposed shells, including the probability of dislodgment and misalignment of valves in high wave energy areas.
Factors affecting brood abandonment in gadwalls (Anas strepera)
Authors: Gendron Michel , Clark Robert G
Published: April 2011

Brood desertion by radio-equipped female gadwalls (Anas strepera) was examined to test three hypotheses regarding proximate factors responsible for post hatch brood abandonment in waterfowl. Gadwall broods with the greatest duckling mortality, independent of brood size, were more likely to be abandoned, providing support for the "brood-success" hypothesis. Our results do not support the "brood-size" hypothesis, as the size of broods immediately prior to female abandonment was no smaller than the size of broods not abandoned. Although brood fate was not related to female body condition, the "salvage-strategy" hypothesis could not be rejected, because experience was a confounding factor and could not be sampled adequately; younger, possibly less-experienced females were more likely to abandon their broods than older females. Further studies, preferably involving experimental manipulations, are needed to adequately address the full array of hypotheses.
Comment: Regulation of moose populations by wolf predation
Authors: Messier François , Joly Damien O
Published: April 2011

We discuss regulation of moose (Alces alces) populations by wolves (Canis lupus) in the context of a recent article by Eberhardt (L.L. Eberhardt. 1997. Can. J. Zool. 75: 1940-1944), who contended that the killing rate of moose by wolves was constant. Further, he argued that wolf population size was proportional to prey density, and that wolf predation exerted a regulatory effect on ungulate-prey numbers. We argue that this combination of functional and numerical responses results in density-independent predation that cannot regulate prey numbers. We discuss the present understanding of wolf-moose interactions and conclude that there is evidence suggesting density dependence in both functional and numerical responses. Further, we conclude that predation by wolves is density-dependent, at least at low moose densities, and therefore can act as a regulatory factor.
Mass change in Antarctic fur seal (Arctocephalus gazella) pups in relation to maternal characteristics at the Kerguèlen Islands
Authors: Guinet Christophe , Lea Mary-Anne , Goldsworthy Simon D
Published: April 2011

Maternal allocation to growth of the pup was measured in Antarctic fur seals (Arctocephalus gazella) at the Kerguèlen Islands during the 1997 austral summer. Absolute mass gain of pups following a maternal foraging trip was independent of the sex of the pup but was positively related to foraging-trip duration and maternal length. However, daily mass gain (i.e., absolute mass gain of the pup divided by foraging-trip duration) decreased with increasing foraging-trip duration but increased with maternal length. While the pup were fasting, their daily mass loss was related to their sex and initial body mass: both heavier pups and female pups lost more mass per day than lighter pups and male pups. The mass-specific rate of mass loss was significantly higher in female than in male pups. Over the study period, the mean growth rate was zero, with no difference between female and male pups. The growth rate in mass of the pup was positively related to maternal length but not to maternal condition, and negatively related to the foraging-trip duration of the mother and the initial mass of the pup. This indicates that during the study period, heavier pups grew more slowly because of their higher rate of daily mass loss during periods of fasting. Interestingly, for a given maternal length, the mean mass of the pup during the study period was higher for male than for female pups, even though the rate of daily mass gain was the same. Such differences are likely to result from sex differences in the mass-specific rate of mass loss. As female pups lose a greater proportion of their mass per day, a zero growth rate (i.e., mass gain only compensating for mass loss) is reached at a lower mass in female pups than in male pups. Our results indicate that maternal allocation does not differ according to the sex of the pup, but suggest that the two sexes follow different growth strategies.
Seabird migration in the Canadian northwest Atlantic Ocean: moulting locations and movement patterns of immature birds
Authors: Huettmann F , Diamond A W
Published: April 2011

All seabirds in the northwest Atlantic Ocean migrate, but timing and routes are not well understood. We evaluate existing knowledge on seabird migration with data from the Programme intégré de recherches sur les oiseaux pélagiques (PIROP) data base, using observations of immature and moulting seabirds to track migration of the following species: Northern Fulmar (Fulmarus glacialis), Greater Shearwater (Puffinus gravis), Northern Gannet (Morus bassanus), Herring Gull (Larus argentatus), Iceland Gull (Larus glaucoides), Glaucous Gull (Larus hyperboreus), Great Black-backed Gull (Larus marinus), Black-legged Kittiwake (Rissa tridactyla), and Thick-billed Murre (Uria lomvia). The distributions of immature and moulting birds show strong seasonal patterns in the northwest Atlantic, and new transition zones and clear biological borderlines for seabird distribution were found. New data on timing and location of moulting Thick-billed Murres are presented. The southern Labrador Banks and Grand Banks (Thick-billed Murre, Northern Fulmar) and southeast Newfoundland and Georges Bank (Greater Shearwater) were identified as moulting grounds. In terms of marine conservation the following areas seem to be important for part of the life cycle of the species named: western Greenland, Cape Cod, Grand Banks, Labrador Banks, southwest Newfoundland, and the Grand Manan area.
The effect of time spent in isolation on the response to novel nonsocial stimulation in the angelfish Pterophyllum scalare
Authors: Gómez-Laplaza Luis M , Morgan Elfed
Published: April 2011

The response of juvenile angelfish (Pterophyllum scalare) to a sudden mechanical stimulus and to a visual stimulus moving slowly across the front wall of the aquarium was studied in solitary fish after 1 and 4 days in isolation. The sudden application of a mechanical stimulus resulted in an escape response followed by immobility. Fish isolated for 1 day resumed swimming earlier than did those isolated for 4 days, i.e., swimming in the latter fish was suppressed for longer. In contrast, a slowly moving visual stimulus evoked persistent approach behaviour in 4-day-isolated fish throughout its presentation, whereas 1-day-isolated fish approached the stimulus only towards the end of its travel. The increased response to the stimuli as time spent in isolation increased is discussed in terms of a change in priorities between opposing tendencies to reinstate social contact with conspecifics and to evade predation, and indicates how time spent in isolation may influence decision-making by individuals.
Ajustement des distances de fuite à l'homme chez Marmota marmota
Authors: Louis Sandrine , Berre Michel Le
Published: April 2011

Flight distance is the quantitative measurement of the reactivity and response of an animal to a disturber or predator. Flight distance seems to vary with group size, distance to shelter, and direction of predator approach. We suggest that other factors may influence flight distance, such as frequency of interactions, presence of a dog with the experimenter, presence of pups in the family group outside the burrows, time of day, and number of animals on the home range outside the burrows. We tested these factors on alpine marmots (Marmota marmota) and bobac marmots (Marmota bobac). Alert and flight distances and exit delays are shorter in groups with frequent interactions and in nonhunted groups (M. marmota). The presence of a dog with the experimenter increased alert and flight distances. The presence of pups outside the burrows during the experiment caused an increase in alert and flight distances and in exit delays. Alert and flight distances decreased during the day. A positive correlation was found between alert and flight distances. Alpine marmots emit very few alarm calls in response to the presence of humans. These results correlated with the hypothesis of accommodation of wildlife to human interactions. Marmots adjust their flight distance, which enables them to maintain certain behaviours in spite of the presence of humans.
Reproductive behavior of the blind mole-rat (Spalax ehrenbergi) in a seminatural burrow system
Authors: Gazit Irit , Terkel Joseph
Published: April 2011

The blind mole-rat (Spalax ehrenbergi) is a fossorial mammal that is solitary and highly aggressive in nature. The consequent difficulties of maintaining this species in captivity have hindered attempts to gain insight into its behavior and reproductive biology. This article describes an innovative artificial tunnel system and management protocol that facilitated our study of the reproductive behavior of the blind mole-rat in captivity. The study employed a naturalistic approach that allowed the animals to establish separate territories in a seminatural tunnel system and to become familiar with each other over a period of months. This approach contrasts with previous unsuccessful attempts in which mole-rats were introduced without a period of acclimation to each other or to the experimental set-up. The results reveal that both the length of acquaintance between a pair of mole-rats and their own control of the timing of encounters are the most significant factors in reducing aggression and stress. Courtship in blind mole-rats is a lengthy process during which the animals gradually become accustomed to one another, which leads to a reduction of aggression and the initiation of positive "contact movements," eventually enabling copulation to occur. Minimal disturbance by the researcher and initiation of encounters by the mole-rats themselves appear to be the factors that led to a successful mating, pregnancy, and, 34 days later, to the female giving birth and rearing the pups in captivity.
Ontogenic changes in prey consumption by the stoneflyParagnetina mediain relation to temporal variation in prey nutrient content
Authors: Duvall Catherine J , Williams D Dudley
Published: April 2011

In Duffin Creek, Ontario, nymphs of the predatory stonefly Paragnetina media (Perlidae) commonly feed on detritus and three prey types: hydropsychid larvae (Hydropsyche sparna and Hydropsyche slossonae), nymphs of the mayfly Baetis tricaudatus, and chironomid larvae belonging to subfamilies Tanypodinae and Orthocladiinae. This study examined temporal changes in the nutrient (lipid and protein) content of these prey to determine if the predator tracks food resources by selecting prey on the basis of nutrient requirements at different stages in its own development. All three common prey types exhibited temporal variation in lipid levels, with peaks occurring at different times: June for the hydropsychids, August for the chironomids, and October for B. tricaudatus. Prey protein levels were less variable. The proportions of the prey types that were eaten varied throughout the year and according to predator size. For example, while small P. media ate mostly detritus, they also consumed early-instar hydropsychids during the larval recruitment period of the latter; mid-sized nymphs included more animal matter in their diet, primarily chironomid larvae; and larger nymphs primarily ate B. tricaudatus. Paragnetina media nymphs in all size categories showed an increase in body lipid level in the autumn, suggesting a general accumulation of lipid reserves in readiness for the winter, although dietary adjustment to accomplish this was detectable only in small P. media. There was no evidence to suggest that P. media selected prey on the basis of the latter's protein content. Male P. media nymphs preyed predominantly on chironomid larvae and included mites in their diet, whereas female nymphs preferred B. tricaudatus and hydropsychids. On a per milligram body mass basis, male nymphs had the higher nutrient gain, since, for both lipid and protein, intake by males was between two and three times that by females. However, male and female bodies had similar lipid contents. We conclude that whereas there is temporal variation both in the nutritional (lipid and protein) content of the common prey of P. media and in this predator's diet, there is only weak evidence for nutrient-resource tracking.
Habitat preferences and population dynamics of Ostracoda in a helocrene spring system
Authors: Mezquita Francesc , Sanz-Brau Antonio , Wansard Guy
Published: April 2011

Habitat features and ostracod populations were monitored monthly between December 1995 and September 1996 in three contiguous pools of a Mediterranean helocrene spring. Principal-components analysis (PCA) of the physical and chemical properties of the water showed that seasonal variations were minor in the site closest to the source (pool 1). Conversely, the site the most distant from the source (pool 3) had the greatest variation in temperature and oxygen and calcium contents. Differences in limnological factors, especially the equilibrium system of carbonates, among sites were also clear from the results obtained with PCA. The cosmopolitan ostracod Cypridopsis vidua predominated in pool 1, where variations in oxygen content and temperature were minimal, and showed a univoltine reproductive pattern. The crenophilous species Potamocypris villosa and Herpetocypris intermedia were the most abundant ostracods at the other two sites, where the development of filamentous algae and Characeae produced a high oxygen concentration and an increase in calcium carbonate precipitation. The latter two species both produced two generations per year. The small size of springs and their position between interstitial and surface waters make them excellent systems for the study of ostracod ecology and the influences of environmental factors upon their life-history traits.
Directionality Effects in Simultaneous Language Interpreting: The Case of Sign Language Interpreters in the Netherlands
Authors: van Dijk Rick , Boers Eveline , Christoffels Ingrid , Hermans Daan
Published: April 2011

The quality of interpretations produced by sign language interpreters was investigated. Twenty-five experienced interpreters were instructed to interpret narratives from (a) spoken Dutch to Sign Language of the Netherlands (SLN), (b) spoken Dutch to Sign Supported Dutch (SSD), and (c) SLN to spoken Dutch. The quality of the interpreted narratives was assessed by 5 certified sign language interpreters who did not participate in the study. Two measures were used to assess interpreting quality: the propositional accuracy of the interpreters’ interpretations and a subjective quality measure. The results showed that the interpreted narratives in the SLN-to-Dutch interpreting direction were of lower quality (on both measures) than the interpreted narratives in the Dutch-to-SLN and Dutch-to-SSD directions. Furthermore, interpreters who had begun acquiring SLN when they entered the interpreter training program performed as well in all 3 interpreting directions as inter- preters who had acquired SLN from birth.
Integrating Technology and Reading Instruction With Children Who Are Deaf or Hard of Hearing: The Effectiveness of the Cornerstones Project
Authors: Wang Ye , Paul Peter V.
Published: April 2011

In a comparison between the Cornerstones approach—a literature-based, technology-infused literacy project—and an instructional method designated the Typical approach, a mixed-method design was used to answer three research questions: (a) Will children who are deaf or hard of hearing demonstrate differences in beginning reading skills as measured by three outcome variables: Identification of Words in Print (or Word Identification), Word Knowledge, and Story Comprehension? (b) Are there carryover effects from the Cornerstones approach to the use of the Typical approach in subsequent experiments? (c) What is the feasibility of using the Cornerstones approach for literacy instruction? There were significant differences between the Typical and Cornerstones approaches in Word Identification and Story Comprehension in Experiments 1 and 2, though none in Word Knowledge or Story Comprehension in Experiment 3. Teacher feedback provided some evidence for the feasibility of using Cornerstones in the classroom.
Real Artificial: Tissue-cultured Meat, Genetically Modified Farm Animals, and Fictions
Authors: McHugh Susan
Published: April 2011

Although touted by promoters as the cutting edge of food science, meat produced in vitro (rather than from a whole animal) is emerging more directly from developments in fine art—more specifically, from the aesthetic experiments of Australian-based artists Oron Catts and Ionat Zurr, who ask: What language do we have to describe the agency of tissue-cultured life? This essay begins to answer this question by tracing a tradition whereby bioengineered meat mediates complex environmental critiques in literary fiction over the past century, including Margaret Atwood's exemplary novel Oryx and Crake (2003), which depicts biotech industries producing three distinct kinds of "real artificial meat," all sourced in genetically modified animals.
How Queer Is Green?
Authors: Garrard Greg
Published: April 2011

Ecofeminism has sought to unravel the interarticulation of gender oppression with the domination of nature, while queer theory has pursued a cultural project of subversion of sexual heteronormativity. Queer ecology brings together and extends both discourses, at once drawing upon contemporary biology and subjecting its taxonomies to skeptical critique. This essay argues that queer theory needs ecocriticism to rescue it from its biophobic assumptions, but it is not yet clear what ecocriticism stands to gain from queer theory. Moreover, it is argued that queer ecology risks the appearance of partial, opportunistic, and conspicuously biased engagement with biology.
"O Dear, What Can the Matter Be?": The Urban Early Republic and the Politics of Popular Song in Benjamin Carr's Federal Overture
Authors: Riordan Liam
Published: April 2011

This essay scrutinizes a musical medley, the Federal Overture, and its performance context at Philadelphia's Southwark Theater in 1794. Benjamin Carr had been commissioned by the Old American Company's managers to compose a piece that would include popular, Federalist, and French Revolutionary songs in an attempt to still audience violence that threatened to ruin their commercial venture in the newly legalized theater of the 1790s. Drawing primarily upon the musical score itself, newspaper accounts, and personal papers, the essay argues that changing performance norms and expectations about audience behavior are crucial to a full understanding of the polarized urban early republic that is too often assessed in narrowly partisan terms. Serious attention to popular culture, like theater music, should aspire to do more than merely add color to a long-established political narrative about the early republic. Because of the success of the Federal Overture as part of the Old American Company's touring repertoire, its circulation as sheet music, and parallel struggles over the performance context of theater in Boston and New York, a microhistorical assessment of Carr's overture helps us access and assess the critically contested public space of postwar but still revolutionary U.S. society.