bluuebunny/crossref_metadata_2025 huggingface dataset:
The case for seasonal evisceration in the holothuroid Eupentacta quinquesemita (Selenka): a reply to Fankboner and Cameron (1985)
Authors: Byrne Maria
Published: April 2011

In a recent publication, Fankboner and Cameron (P. V. Fankboner and J. L. Cameron. 1985. Can. J. Zool. 63: 2888–2892) contested the conclusions of Byrne (M. Byrne. 1985. Ophelia, 24: 75–90) who had made a case for the incidence of seasonal evisceration (visceral autotomy) in the holothuroid Eupentacta quinquesemita. In this reply, the results of Byrne (1985) are reexamined. It is shown that the evidence presented amply demonstrates the existence of seasonal evisceration and that the objections of Fankboner and Cameron (1985) are based on their misreading of Byrne (1985). In addition, the mechanisms causing seasonal loss of the viscera by aspidochirote and dendrochirote holothuroids are discussed.
Freshwater sponges (Porifera, Spongillidae) of eastern Canada: taxonomy, distribution, and ecology
Authors: Ricciardi Anthony , Reiswig Henry M.
Published: April 2011

During a recent survey of the freshwater sponges of eastern Canada (from Ontario to Newfoundland), 15 species were recorded, representing approximately 50% of the total number of species known from North America. Radiospongilla crateriformis, Spongilla aspinosa, and Trochospongilla horrida are reported from Canada for the first time. Two problematic species, Corvosporigilla novaeterrae and Spongilla johanseni, are reviewed and their status is revised. Detailed notes on taxonomy, morphology, distribution, and ecology are given. New limits of tolerance with respect to pH, water temperature, and calcium and magnesium concentrations are established for several species. A taxonomic key to the freshwater sponges of eastern Canada is presented.
Growth and secondary production of Paracapnia angulata Hanson (Plecoptera; Capniidae) in Appalachian streams affected by acid precipitation
Authors: Griffith Michael B. , Perry Sue A. , Perry William B.
Published: April 2011

Paracapnia angulata in West Virginia occurs in headwater streams that range in pH from 4.5 to 7.5. It is representative of a number of species of Plecoptera, which often increase in abundance in acidic streams because they are tolerant of low pH and related changes in water quality associated with acid precipitation. We compared growth rates and secondary production of P. angulata in four streams, SFR, WS4, WS3, and HSR, in which mean streamwater pH was 4.26, 5.99, 6.07, and 7.48, respectively. Mean specific growth rates, in terms of dry mass for P. angulata, were higher in the two neutral streams than in the more alkaline stream or the acidic stream. Secondary production of P. angulata was highest in the acidic stream SFR, 106.2 ± 16.4 mg∙m−2∙yr−1 (mean ± 2 SE), and was 34.0 ± 12.1 mg∙m−2∙yr−1 in WS4, 32.7 ± 3.8 mg∙m−2∙yr−1 in WS3, and 35.4 ± 3.6 mg∙m−2∙yr−1 in HSR. The increased secondary production of P. angulata was related to greater mean abundance and biomass in SFR; and the production/biomass ratio for this acidic stream was lower than for the other streams.
Early maternal investment and growth in reindeer
Authors: Kojola I.
Published: April 2011

I studied whether females in a herd of semidomesticated reindeer (Rangifer tarandus) in Finland invest more heavily in male than in female offspring and whether the mother's body size and condition have different effects on growth rates of male and female offspring. The results did not provide evidence of different preweaning investment in male and female offspring. Proportional mass loss of breeding females during calving was greater when the calf was male than when it was female, but change in mass between consecutive autumns did not depend on the sex of the calf. In general, the growth of male and female calves depended in approximately similar fashion on maternal characteristics, but amongst the male calves only, the growth rate from birth until the following November depended on the mother's change in mass the previous winter. Mass loss of parturient females was inversely related to mass loss during pregnancy. Females that experienced heavy mass loss from November until postcalving gained the most mass before the following November. Winter food supplementation probably led to large body masses and a low mortality rate of calves and might have masked differences in reproductive costs associated with producing male and female calves.
6-Methoxy-2-benzoxazolinone and photoperiod: prenatal and postnatal influences on reproductive development in prairie voles (Microtus ochrogaster ochrogaster)
Authors: Nelson Randy J. , Blom Joan M. C.
Published: April 2011

The effects of photoperiod and 6-methoxy-2-benzoxazolinone (6-MBOA) on the gonadal development of prairie voles was studied when this plant compound was available to pups in utero, during nursing, or postweaning. In part 1, pregnant voles exposed to long or short day lengths were fed food in which 6-MBOA was present (50 μg of 6-MBOA/g food) or absent prior to the birth of their young; all of these dams received a diet that lacked 6-MBOA after the pups were born. Other females were fed food without 6-MBOA throughout pregnancy, but received one of the diets during lactation. Short days inhibited reproductive development in male offspring, affected pup survival, and enhanced pelage development. Postnatal exposure to 6-MBOA did not affect the reproductive function of males. In contrast, prenatal exposure to 6-MBOA accelerated reproductive development among short-day males. Prenatal exposure to 6-MBOA did not affect survival of short-day males, but reduced survival of long-day pups. Prenatal 6-MBOA treatment affected the sex ratio of pups that survived until weaning (13:21; male:female) and of pups that died prior to weaning (26:5). In contrast, photoperiod did not affect reproductive function in female voles. Although reproductive function appears to be uncoupled from photoperiodic regulation, female prairie voles processed photoperiodic information; pelage development was enhanced among short-day females. In part II, breeding pairs were exposed to long or short days and fed food devoid of 6-MBOA prior to the birth of the young. On the day of birth, and for the following 3 weeks, either 6-MBOA-free or 6-MBOA-enriehed food was provided. After weaning, pups received their parents type of food until autopsy 3 or 7 weeks later. Again, photoperiod affected male, but not female, reproductive function. No consistent pattern of results from postnatal exposure to 6-MBOA was discerned for either males or females. Acceleration of reproductive function among short-day males because of prenatal influences may, be involved in the rapid rate of sexual maturation observed prior to peak population densities of microtine rodents. Because males of this species induce females into estrus, male prairie voles may depend on environmental cues to regulate reproductive function, while females may respond only to males. The physiological and ecological implications of these data are discussed.
Endoscopic visualization of the functional morphology of the ctenidia of the unionid mussel Pyganodon cataracta
Authors: Tankersley Richard A , Dimock Jr. Ronald V.
Published: April 2011

During reproduction, the outer demibranchs of the unionid mussel Pyganodon cataracta serve as marsupia, with incubation of the developing shelled glochidia larvae occurring within the water tubes. In this study, recently developed endoscopic video analysis techniques were employed to examine in vivo the dynamics of filter feeding and water transport in mussels during gravid and postgravid periods. Particles entering the mantle cavity and retained by the gills were transported to the palps in a complex mucus-bound cord by the ventral food groove of the medial ctenidia. Larval incubation and ctenidial swelling impeded flow around the lateral demibranchs, although marsupial ctenidia were still actively involved in suspension feeding. Cilia on the distended ventral edges of marsupial demibranchs were often observed transporting filtered particles to the frontal surface of the medial gills. Larvae within the brood chambers were morphologically isolated from the surrounding medium by dorsal brood caps on the primary water tubes. Direct observations of the secondary water tubes of marsupial gills constructed during periods of larval incubation confirmed their role as temporary lumina for water transport during gravid periods. Time-lapse video recordings revealed that mature larvae are released from the brood chambers via the suprabranchial cavity and exhalant siphon by rapid adductions of the valves and contractions of the brooding demibranchs.
A revision of the Nearctic Pseudocollinella Duda (Diptera; Sphaeroceridae)
Authors: Marshall S. A. , Smith I. P.
Published: April 2011

The genus Pseudocollinella Duda, 1924, treated by recent authors as part of the genus Opacifrons Duda, 1918, is redefined and revised for the Nearctic region. Pseudocollinella flavilabris (Hackman) and P. abhorrens (Roháček) are recorded from the Nearctic region for the first time. All of the above species, plus the North American species P. caelobata (Spuler), P. pellucida (Spuler), and P. sciaspidis (Spuler) and the European species P. septentrionalis (Stenhammar), P. humida (Haliday), P. jorlii (Carles-Tolrá), P. tunisica (Papp), and P. ochrea (Papp), are given as new combinations. Pseudocollinella aquilifrons Marshall, P. attractans Marshall, P. arctopellucida Marshall, P. boreosciaspidis Marshall, P. charlottensis Marshall, P. hirsutipellucida Marshall, P. parapellucida Marshall, P. parasciaspidis Marshall, and P. utapellucida Marshall are described as new. A key to all species is given and their phylogenetic relationships are discussed.
The effects of an ectoparasite on reproductive success in the great tit: a 3-year experimental study
Authors: Allander Klas
Published: April 2011

The effects of ectoparasites on host reproductive success have been studied in a variety of bird species. Most of these studies concern either colonial or hole-nesting birds, which have been suspected of being particularly susceptible to parasites because of their social habits and (or) reuse of old nests. The effects of a horizontally transmitted flea, Ceratophyllus gallinae, on the reproductive success of hole-nesting great tits,Parus major, were experimentally studied over 3 years. Leaving nests in nest boxes in the intervals between breeding seasons does not result in a significant increase in parasite abundance in comparison with nest boxes cleaned between seasons. Flea abundance was reduced by spraying random nests with an insecticide during host egg laying. There were no significant effects of ectoparasite removal on clutch size, number of fledged young, hatching success, or fledging success in any of the 3 years, although a significant interaction between year and treatment in nestling body mass was observed. Thus, in 1 of the 3 years, body mass of nestlings in the sprayed boxes was, on average, significantly greater than that of controls. There was also a negative correlation between flea abundance and mean body mass of the brood. In addition, nestlings produced in flea-free boxes had a significantly higher probability of recruiting locally than nestlings from control nests. The effects of ectoparasites seem to vary over time and also among host populations, which implies that the effects of parasites may interact with other environmental factors.
Histological and ultrastructural study of the stomach of the air-breathing Ancistrus multispinnis (Siluriformes, Teleostei)
Authors: Satora L
Published: April 2011

Histological and ultrastructural analyses of selected segments of the digestive tract of the fish Ancistrus multispinnis were done, particular attention being paid to the cytological barrier between blood and air. Three regions can be distinguished in the stomach of A. multispinnis: cardia, corpus, and pylorus. The histological organization of the cardia and pylorus is similar to that in other fish species, but the organization of the corpus is distinct. The cell bodies of the epithelial cells of the corpus are located in the capillary mesh, while their flattened extensions cover the adjacent capillaries. This specialization reduces the thickness of the blood-air interface, which may influence the diffusion of gases in the stomach. Some epithelial cells in the stomach corpus contain numerous lamellar bodies. It is suggested that these produce a substance similar in function to the lung surfactant of Dipnoi, certain Amphibia, and Mammalia.
An intergeneric hybrid in the family Phocoenidae
Authors: Baird Robin W , Willis Pamela M , Guenther Tamara J , Wilson Paul J , White Bradley N
Published: April 2011

A 60-cm female fetus recovered from a Dall's porpoise (Phocoenoides dalli) found dead in southern British Columbia was fathered by a harbour porpoise (Phocoena phocoena). This is the first report of a hybrid within the family Phocoenidae and one of the first well-documented cases of cetacean hybridization in the wild. In several morphological features, the hybrid was either intermediate between the parental species (e.g., vertebral count) or more similar to the harbour porpoise than to the Dall's porpoise (e.g., colour pattern, relative position of the flipper, dorsal fin height). The fetal colour pattern (with a clear mouth-to-flipper stripe, as is found in the harbour porpoise) is similar to that reported for a fetus recovered from a Dall's porpoise to off California. Hybrid status was confirmed through genetic analysis, with species-specific repetitive DNA sequences of both the harbour and Dall's porpoise being found in the fetus. Atypically pigmented porpoises (usually traveling with and behaving like Dall's porpoises) are regularly observed in the area around southern Vancouver Island. We suggest that these abnormally pigmented animals, as well as the previously noted fetus from California, may also represent hybridization events.
Feeding behaviour, brain serotonergic activity levels, and energy reserves of Arctic char (Salvelinus alpinus) within a dominance hierarchy
Authors: Alanärä Anders , Winberg Svante , Brännäs Eva , Kiessling Anders , Höglund Erik , Elofsson Ulf
Published: April 2011

The relationships between feeding activity, brain serotonergic activity level, and energy reserves in eight groups of Arctic char (Salvelinus alpinus) were evaluated using self-feeders in combination with passive integrated transponder (PIT) tags. Serotonin concentrations were measured in the brain stem, telencephalon, and hypothalamus. Energy reserves were measured, as fat levels, in muscle and mesenteric tissue. The self-feeding activity level was found to correlate positively (P < 0.05) with the growth rate and negatively (P < 0.05) with the serotonergic activity levels in the brain stem and telencephalon. No significant relationship was found, however, between the number of trigger activations and the muscle or mesenteric tissue lipid level. One or, in some cases, two fish in each group clearly dominated the activation of the trigger, and showed the highest growth rates and lowest stress levels, measured as brain serotonergic activity. Subordinate fish (one to three individuals) hardly ever activated the trigger, but showed relatively high growth rates and brain serotonergic activity levels that did not differ significantly from those of dominant fish. The remaining individuals showed very little feeding activity and low growth rates. In addition, brain serotonergic activity levels were significantly higher than in fish in the former two categories, indicating that the subordinate fish suffered from stress and had a low social rank.
Patterns and determinants of helminth communities in the Acipenseridae (Actinopterygii: Chondrostei), with special reference to the lake sturgeon, Acipenser fulvescens
Authors: Choudhury Anindo , Dick Terry A
Published: April 2011

Patterns, processes, and some hypotheses regarding the structure of helminth communities in freshwater fishes have been investigated using sturgeons (Acipenseridae), a widely distributed group of basal actinopterygian fishes. Analyses at the infracommunity and component-community levels for one species, Acipenser fulvescens, indicated occasionally dense, but isolationist, gut helminth communities with moderate species richness and a high degree of predictability conferred by host-specific helminths that dominated the communities. Largely predictable helminth communities are also characteristic of acipenserids from Siberian and Ponto-Caspian drainages and basins. Although host specificity was the major determinant of helminth community diversity in most acipenserids, exceptions were found in sturgeons of the Aral Sea drainages, where non-host-specific parasites dominated the helminth communities. Gut complexity and evolutionary age were both found to be poor predictors of community richness in sturgeons and other basal actinopterygians. The stochastic component of the gut helminth fauna is determined by shared trophic category and sympatry with other major benthivorous fishes, mainly benthic coregonines in Holarctic drainages and benthic ostariophysans (e.g., cypriniforms) elsewhere. Although some predictions of "evolutionarily mature" communities are partially fulfilled, the authors of this study caution that owing to differences in the biology and history of individual species and groups and the diversity of fishes in general, broad generalizations about the factors shaping fish parasite communities will be difficult to make.
Population biology of an endangered butterfly, Lycaeides melissa samuelis (Lepidoptera; Lycaenidae): genetic variation, gene flow, and taxonomic status
Authors: Packer Laurence , Taylor John S , Savignano Dolores A , Bleser Catherine A , Lane Cynthia P , Sommers Laura A
Published: April 2011

We present data from 34 allozyme loci to test whether the Karner Blue butterfly is specifically differentiated from the Melissa Blue. Furthermore, as the Karner Blue is an endangered organism of low vagility that occurs predominantly in small, widely separated populations, we investigated (i) whether the Karner Blue is depauperate in genetic variation and (ii) whether gene flow between sampled populations is unusually low. Genetic identities between New York and Wisconsin populations of the Karner Blue and a sample of Melissa Blue from Minnesota are all statistically indistinguishable. Neither genetic identity data nor application of the phylogenetic species concept support formal recognition of the Karner Blue as a species separate from the Melissa Blue. Nonetheless, the data indicate that gene flow among the samples was very low compared with that among populations of other Lepidoptera. Heterozygosity estimates for all three samples were comparable to data for other Lepidoptera and indicate that the Karner Blue populations surveyed are not under immediate threat of extirpation due to loss of genetic diversity. Although the available data are limited, if the Karner Blue is to be managed as an evolutionarily significant unit, then the eastern and western populations should probably be treated independently and each should receive high conservation priority.
Determining the age of garter snakes (Thamnophis spp.) by means of skeletochronology
Authors: Waye Heather L , Gregory Patrick T
Published: April 2011

Individual and population-specific patterns of growth, and variations in these patterns, can be determined if the age of individuals is known; this allows the dynamics of populations to be more accurately modelled and projected into the future and provides a better understanding of the life history. Besides contributing to our understanding of the fundamental ecological issue of limitation of distribution and abundance, such knowledge is critical to management or conservation plans for many species. Skeletochronology, the reading of growth layers in bony structures, has been used extensively to determine the age of individual fish and, to a lesser extent, of reptiles and amphibians. This study evaluates the use of skeletochronology to determine the age of garter snakes (Thamnophis spp.), with emphasis on the development of techniques that allow the sampling of bone structures from live animals. Layers were observed in the caudal vertebrae of two species of garter snakes, using standard histological techniques, and were consistent in number within individual snakes, with some variability. The validity of growth layers as an indicator of age was established using snakes raised in the laboratory under differing hibernation regimes. Skeletochronology has the potential to be an important and useful technique for the study of age in snakes, but is very labour-intensive and is best used as part of a large, long-term project.
Intraspecific morphological variation in a freshwater copepod (Crustacea) in relation to geographic distribution and environment
Authors: Elgmork Kåre , Halvorsen Gunnar
Published: April 2011

Intraspecific variation in morphology was studied by means of morphometric analysis in 52 populations of the freshwater planktonic copepod Cyclops scutifer G.O. Sars from Eurasia and North America. The species showed very conservative morphology over wide geographic areas and subspecies could not be established. Variations occurred irregularly, and morphologically very similar forms were found widely separated on different continents. Correlation analysis revealed that many morphological relations were correlated with environmental factors such as depth, temperature, and trophic condition. Variations in body proportions were thus related to environmental factors rather than to geographic distance.
Karyotypic variation in populations of deer mice (Peromyscus maniculatus) from eastern Canada and the northeastern United States
Authors: Unice Stephanie M. Myers , Hale David W , Greenbaum Ira F
Published: April 2011

The karyotypes of deer mice (Peromyscus maniculatus) from populations of five subspecies from the northeastern United States and eastern Canada were analyzed by G- and C-banding. Within an invariant diploid number of 48, intra- and inter-populational variation in the number of autosomal arms (80-86) was attributable to a pericentric inversion (chromosome 8) and (or) the presence of heterochromatic short arms (chromosomes 8, 10, 12, and 19). The plesiomorphic (noninverted) condition of chromosome 10 in these five populations is unique among deer mice; previous chromosome-banding studies of P. maniculatus report data for geographically central or western populations and indicate only the derived (inverted) condition of chromosome 10. As the plesiomorphic condition of chromosome 10 is apparently restricted to the northeastern forest form of P. maniculatus, the morphology of this chromosome potentially represents a simple and discrete character for resolving the historically problematic question of the specific status of the eastern grassland and forest morphotypes of deer mice.
The parasites of Pacific halibut (Hippoglossus stenolepis) in the eastern North Pacific: host-level influences
Authors: Blaylock R B , Holmes J C , Margolis L
Published: April 2011

Fifty-nine metazoan parasite taxa were identified from 536 Pacific halibut (Hippoglossus stenolepis) of three size classes (recruits (<10 cm), juveniles (10-55 cm), and subadults/adults (55-102 cm)). Pacific halibut harbor parasite communities that are among the richest and most abundant found in those marine fishes studied to date. The parasites are largely host generalists, being found in a wide variety of marine fishes. These three features appear to be due, in part, to the interplay of the large size, wide diet, extensive mobility, and long life-span of halibut, plus the lack of specificity in the marine system and the ability of marine parasites to be transferred trophically from prey fishes to piscivorous fishes. The parasite community in halibut is more similar to those in other flatfishes than to those in ecological analogs, suggesting that phylogeny is an important determinant as well. There are no differences in infections due to host sex. Recruits harbor few parasites, but parasite species and particularly individuals accumulate with host age and length and reflect the shift from a crustacean to a fish diet. Growth rate influences the number of parasite individuals in a given fish, probably reflecting food intake. The smallest fish in the 5-, 6-, and 7-year age-classes have more parasite individuals than slightly larger fish in the same age-class and weigh less than expected for their size; they may be debilitated by parasites.
Effects of food and predators on the home-range sizes of Arctic ground squirrel (Spermophilus parryii)
Authors: Hubbs Anne H , Boonstra Rudy
Published: April 2011

We used radiotelemetry to study the effects of food addition and predator reduction on the home-range sizes of adult Arctic ground squirrels (Spermophilus parryii) on large-scale experimental grids in the boreal forest of the southwestern Yukon Territory. Home ranges were 2-7 times smaller on food-supplemented grids than on nonsupplemented grids, regardless of whether large mammalian predators were present. Similarly, core areas (where 50% of activities occur) were 8-11 times smaller on food-supplemented grids. Food availability rather than predator presence primarily determined the sizes of home ranges and core areas of Arctic ground squirrels.
A review of northern Canadian spiders of the genus Agyneta (Araneae, Linyphiidae), with descriptions of two new species
Authors: Saaristo Michael I , Koponen Seppo
Published: April 2011

Agyneta amersaxatilis n.sp. and Agyneta dynica n.sp. are described from Canada. Agyneta amersaxatilis, preferring moist sites, ranges from maritime Canada and Maine in the east to Alberta in the west. Agyneta dynica is known only from the type locality in northern Quebec. The identity of Agyneta nigripes (Simon, 1884), Agyneta levinsenii (Soerensen, 1898) n.comb., Agyneta maritima (Emerton, 1919), Agyneta simplex (Emerton, 1926) n.comb., Agyneta jacksoni (Braendegaard, 1937) n.stat., n.comb., and Agyneta alaskensis (Holm, 1960) rev.stat. is discussed and diagnostic drawings are presented. A new synonymy, Meioneta tumoa (Chamberlin and Ivie, 1933) = Agyneta simplex (Emerton, 1926) n.syn., is proposed. Marked geographical variation was found inA. nigripes.
Population-size estimators and unequal catchability in painted turtles
Authors: Koper Nicola , Brooks Ronald J
Published: April 2011

Most methods of estimating population size from mark-recapture data assume equal catchability. Failure to meet this assumption may have profound effects on population-size estimates. We used 3 sampling methods to compare population-size estimates derived from Petersen, Schumacher and Eschmeyer, and Jolly-Seber models with the true size of a closed population of painted turtles (Chrysemys picta) in Algonquin Park, Ontario. We found significant variation in capture probabilities, and almost all population-size estimates were far below the true population size. To try to improve the accuracy of the estimates, we applied 4 techniques commonly recommended for reducing bias when catchability is unequal: (i) changing sampling methods, (ii) using several sampling methods simultaneously, (iii) dividing the population by sex, and (iv) calculating population sizes using the computer program CAPTURE. None of the 4 methods reduced the error that resulted from unequal catchability in any of the estimates sufficiently for these methods to be suitable for management of populations or for ecological research.
Litter sex ratios in a food-supplemented population of Peromyscus mexicanus
Authors: Duquette Laurel S , Millar John S
Published: April 2011

We examined the tertiary sex ratio of litters in a wild population of the tropical mouse Peromyscus mexicanus for evidence of facultative adjustment of the sex ratio as a function of (i) three maternal characteristics, mass at conception, litter parity, and access to a food supplement, and (ii) rainfall and temperature around the time of early gestation and around the time of birth. We examined unreduced litters (litters that had not experienced losses during gestation or lactation, usually 3 pups) separately from litters of all sizes in order to distinguish between prenatal (unreduced litters) and postnatal (all litters) shifts in litter composition. We also examined a sample of litters that were enumerated at birth for further evidence of prenatal adjustment of the sex ratio. None of the independent variables were significant predictors of the frequency of male pups. Furthermore, we found no evidence that litters of any size deviate from a sex ratio of 1.0, whether enumerated at birth or at weaning. Sex-ratio shifts occur in other species of Peromyscus, but P. mexicanus has a low reproductive potential, and adjustment of litter composition may not occur because such a strategy is too costly and too risky.
Quantitative comparison of tree roosts used by red bats (Lasiurus borealis) and Seminole bats (L. seminolus)
Authors: Menzel Michael A , Carter Timothy C , Chapman Brian R , Laerm Joshua
Published: April 2011

We radio-tracked 11 red bats (Lasiurus borealis) and 5 Seminole bats (L. seminolus) to 64 and 34 day roosts, respectively. Individuals of both species were found roosting within the canopy of the roost trees, clinging to leaf petioles or the tips of small branches (<4 cm in diameter). Red bats roosted primarily in hardwoods (97%), whereas the roosts of Seminole bats were located primarily in pines (94%). Ten of the 16 roost-site variables examined differed significantly between red bats and Seminole bats: number of trees in the overstory, overstory height, understory richness and diversity, overstory richness, diversity, and evenness, roost-tree diameter, percent canopy closure, and percentage of conifers in the overstory. These differences were related directly to the differential use of roosting habitats by the two species. The roosts of red bats were located in pine - mixed hardwood communities and bottomland hardwood swamps, while the roosts of Seminole bats were located in communities dominated by pines. To examine within-stand roost selection, the diameter, height, and species composition of roost trees used by red and Seminole bats were compared with those of neighboring trees. Roost trees of red and Seminole bats had significantly larger diameters and were significantly taller than surrounding trees. Day roosts of red and Seminole bats were located in 18 and 5 tree species, respectively. The tree species used differed significantly from expected for the red bat but not for the Seminole bat.
Activity patterns in relation to body mass and ambient temperature among overwintering cotton rats (Sigmodon hispidus)
Authors: Eifler Maria A , Slade Norman A
Published: April 2011

We examined mass-specific activity patterns among overwintering cotton rats (Sigmodon hispidus) in northeastern Kansas. We livetrapped animals for a 24-h period, checking traps every 2 h. Trapping occurred every 2 weeks for 5 months. We estimated probability of capture for each mass class, time class, and date, then tested for differences in probability of capture (i.e., activity levels) using a General Linear Model with temperature as a covariate. Large cotton rats were significantly less active than small and intermediate-sized cotton rats. Activity of small cotton rats increased with decreasing temperature, whereas larger cotton rats were less responsive to temperature. Finally, activity levels of large and small cotton rats did not vary significantly with time of day, but intermediate-sized cotton rats were significantly less likely to be captured during the night than at dusk.
Survival and reproduction of resident and immigrant female root voles (Microtus oeconomus)
Authors: Johannesen Edda , Andreassen Harry P
Published: April 2011

Many spatially explicit population models assume that residents and immigrants have equal vital rates (survival and reproduction). We tested this assumption by using root vole (Microtus oeconomus) populations in an experimental setting where habitat patches were embedded in an uninhabitable transition habitat. Place of birth and matrilineal relations were known for all animals in 12 different populations. Females were classified as residents or immigrants depending on whether they stayed and reproduced in their natal patch or settled and reproduced in a foreign patch. We compared survival probabilities, derived from the Jolly-Seber-Cormack model, and reproductive parameters between resident and immigrant root vole females. We found no difference between residents and immigrants for any of the parameters examined. Nor did we find any significant difference in net reproductive rate (R0) derived from Leslie models utilizing estimated demographic parameters for residents and immigrants. We conclude that the assumption of equal vital rates may be justified, at least at the spatial scale considered in this study.
Seasonal and diel changes in habitat use by juvenile bull trout (Salvelinus confluentus) and cutthroat trout (Oncorhynchus clarki) in a mountain stream
Authors: Bonneau Joseph L , Scarnecchia Dennis L
Published: April 2011

Habitat use by juvenile bull trout (Salvelinus confluentus) and cutthroat trout (Oncorhynchus clarki) in Trestle Creek, Idaho, changed seasonally and dielly. Both cutthroat and bull trout selected pools over riffles in both summer and winter. Both species used a wide range of depths at night but were absent from shallow water (<15 cm) during the day in summer and winter. During summer, juveniles of both species occupied areas of lower velocity water at night than during the day. Both species also occupied lower velocity water during winter days than summer days. During winter days, juvenile bull trout were located below or directly on cobble substrate, whereas cutthroat trout often formed aggregations suspended in the water column of large pools. Both species were more closely associated with cover during the day, and made the greatest use of cover during winter days. Land management activities resulting in decreased pool habitat, instream cover, and stream-bed stability may be especially detrimental to bull trout and cutthroat trout in winter.
Reproductive variables of American black ducks along the St. Lawrence estuary, 1963-1991
Authors: Bélanger Luc , Reed Austin , DesGranges Jean-Luc
Published: April 2011

We examine data from different surveys conducted from 1963 to 1991 in the Baie de lIsle Verte National WildlifeArea and the surrounding offshore islands, an approximately 20-km2 coastal segment of the St.Lawrence estuary in Quebec.We summarize data regarding various aspects of the nesting ecology of the American black duck (Anas rubripes) (n = 812nests). Mean laying date, average clutch size, and apparent nesting success did not differ among years (P > 0.05). Black ducksnested earlier on islands (mean Julian date 120.0 vs. 121.3;P = 0.03), but mean clutch size and nesting success on islands didnot differ from those on the mainland (P> 0.05). Among mainland-nesting black ducks, those nesting in mixed stands of treesand bushes initiated nests almost 10 days earlier than those nesting in the two other types of nest cover (mean Julian date 124.0vs. 134.4 and 139.6). Black ducks nesting in such habitats as woodlots, peat bogs, or shrubland laid a larger number of eggsthan those nesting in the two other habitat types (mean 9.7 vs. 8.8 and 9.4). Finally, we observed that nesting success of ducksnesting in woodlots, peat bogs, and shrubland and in mixed stands of trees and bushes or of herbaceous plants and shrubs wasup to three times higher than at other sites (P<= 0.05). We conclude that in addition to protection and restoration of existingislands, more emphasis should be placed on conserving peat bogs, coniferous woodlots, and shrubland, because they alsoconstitute good mainland-nesting habitat for black ducks along the St. Lawrence estuary.
Parental-care responses by yellow warblers (Dendroica petechia) to simultaneous manipulations of food abundance and brood size
Authors: Lozano G A , Lemon R E
Published: April 2011

Theoretical models view biparental care as a state of equilibrium that can be maintained only when the amount of parental care provided by one parent depends on the amount provided by its mate. According to these models, biparental care results when a decrease in the contribution of one parent is partially, but not completely, compensated for by an increase in the contribution of the other parent. Furthermore, this equilibrium state can only be stable if any other external factor affects male and female effort equally. We used yellow warblers (Dendroica petechia) to examine whether changes in brood size and food abundance affect the parental contributions of the sexes equally. Supplemental food did not affect parental care by either sex, but brood size did. Both males and females provided more to larger broods, and in large broods only, their provisioning rates increased with nestling age. Parental effort per nestling was similar in the two sexes, being higher for smaller broods and increasing with nestling age. Based on brood biomass, parental effort was greater for smaller broods, and decreased with nestling age in females only. Therefore, in agreement with current models of the maintenance of biparental care, the effects of brood size and nestling age on parental care did not differ significantly between the sexes. Nonetheless, data from other species and theory indicate that the costs and benefits of providing parental care differ between the sexes, so it is unlikely that biparental care can be maintained solely by a partial compensation response.
Differences in attachment of water mites on water boatmen: further evidence of differential parasitism and possible exclusion of a host from part of its potential range
Authors: Bennett AMR , Scudder GGE
Published: April 2011

This paper is the latest study on the distribution of two sympatric species of water boatmen in saline lakes in British Columbia. It is a further examination of a study by Smith, who found that parasitic water mites have higher prevalence and abundance on Cenocorixa expleta than on C. bifida. He hypothesized that this is one of the main factors responsible for the small populations of C. expleta in lakes below 13 000 µS · cm-1. We performed laboratory experiments with the mite Eylais euryhalina on two different wing morphs of the two host species. Over 8 days, we found higher prevalence and abundance of mites on the predominant, flight-incapable morph of C. expleta than on the predominant, flight-capable morph of C. bifida. Eylais euryhalina attached over most of the abdominal terga of C. expleta, but generally attached only to the permanently non-sclerotized thoracico-abdominal membrane of C. bifida. Infecting both wing morphs of both species showed that locations of mite attachment differed according to the wing morph and the associated differences in sclerotization, whereas the effect of species was equivocal. We hypothesize that a factor in C. expleta's exclusion is the greater potential mite-attachment area of its predominant, unsclerotized morph.
Antipredator benefits of nest-site selection in Black-legged Kittiwakes
Authors: Regehr Heidi M , Rodway Michael S , Montevecchi William A
Published: April 2011

We investigated the relationship between nest-site characteristics and breeding performance of Black-legged Kittiwakes (Rissa tridactyla) on Great Island, Newfoundland, during 2 years of extreme predation pressure. The nest-site feature most consistently associated with egg and chick survival was rock overhang above the nest. The presence of rock projections beside nests was positively correlated with success in 1993, and rock protrusions below the nest were not associated with breeding success in either year. Central position in the colony was positively correlated and nest density negatively correlated with success in 1992. Consistent differences in chick production among colony regions reflected differences in large-scale cliff structure and predator accessibility. This study implicates large- and fine-scale aspects of nest-site selection by Black-legged Kittiwakes, with large-scale cliff structure being the most important.
How red-backed voles find habitat patches
Authors: Gillis Elizabeth A , Nams Vilis O
Published: April 2011

The purpose of this study was to discover how red-backed voles (Clethrionomys gapperi pallescens) found preferred habitat patches. Two hypotheses tested were that voles discover habitat patches by chance, and that they perceive them from a distance and travel towards them. The distance at which voles detected a wooded habitat was determined by measuring the accuracy of orientation at different distances. Animals were released in an unfamiliar grassland at one of five distances (0-20 m) from the boundary of an adjacent unfamiliar woodland and tracked using the spool and line technique. At all distances, the voles oriented towards the woods. However, their reaction was much weaker at greater distances. Thus, reaction to the woodland was not an "all or nothing response": the closer the voles came to the woods, the straighter were their paths and the more directly they oriented towards the woods. This adds to our understanding of how habitat fragmentation affects voles. A between-patch distance of 20 m does not completely isolate red-backed voles, but a distance equivalent to a home-range diameter (60-70 m) likely would.
Host and environmental correlates of body size in ticks (Acari: Argasidae and Ixodidae)
Authors: Poulin Robert
Published: April 2011

To evaluate the influence of host mass and environmental temperature on the evolution of body size in ticks, a comparative analysis was performed using data from 193 species. Using the 20 possible phylogenetically independent contrasts among tick species, no relationship was found between body size of female ticks and either host mass or temperature. The statistical power of these analyses was low. Within the two most speciose genera of soft ticks, however, separate cross-species analyses revealed a positive and highly significant relationship between female tick size and host mass. Also, within the two most speciose genera of hard ticks, cross-species analyses showed a positive and highly significant relationship between scutum size of female ticks and host mass. The latter correlation is based on measurements of tick body size that are independent of the level of blood engorgement. No effect of temperature was observed in the within-genera analyses. These within-genera trends may be artefacts of unknown phylogenetic relationships. Another explanation, however, is that host body mass may have influenced the evolution of tick body size.
Population abundance and dispersal in Akodonazarae (pampean grassland mouse) in Argentina
Authors: Cittadino Emilio A , Busch María , Kravetz Fernando O
Published: April 2011

Dispersal of Akodon azarae, the pampean grassland mouse, was studied during different phases of the annual cycleof population abundance in longitudinal habitats in agroecosystems. Dispersal rates were higher in the increasing and decliningphases than at times of low and peak densities. The pattern of variation in dispersal rates may have been caused by bothpopulation dynamics and structure, as well by changes in habitat variables that influence rodent survival and reproduction. Lowdispersal rates in spring were related to reproductive activity, which restricts females movements and causes large movementsof males within their home ranges. In autumn, with increasing density, dispersal should be a good strategy for individuals thatdid not gain access to vacant sites. In contrast, in early winter, when density is high and there are no vacant sites, the costs ofdispersal (mortality and competition) are not compensated for by enhanced chances of reproduction. Finally, dispersalincreases after the high mortality experienced by the population in winter, when individuals leave their home ranges, probablybecause of the impoverishment of the habitat during this period reported in earlier works. Dispersal plays a significant role inthe population dynamics of A. azarae and contributes to the persistence of local populations through recolonization.
Phylogenetic status of North American wapiti( Cervus elaphus) subspecies
Authors: Polziehn R O , Hamr J , Mallory F F , Strobeck C
Published: April 2011

By the turn of the century, North American elk, or wapiti (Cervus elaphus), had been extirpated from all regions ofthe continent and two subspecies were extinct. The recovery of wapiti is largely a response to the large number of relocatedRocky Mountain (C. e. nelsoni) and Manitoban wapiti (C. e. manitobensis). A phylogenetic study was performed to determinethe present genetic relationships among tule (C. e. nannodes), Roosevelt (C. e. roosevelti), Rocky Mountain, and Manitobansubspecies, using sequences from the D-loop region of the mitochondrial DNA of 28 individuals. All Roosevelt wapiti weregrouped together, as were tule wapiti, which supports the classification of tule and Roosevelt subspecies. Yellowstone, ElkIsland, and Riding Mountain National Parks have not introduced wapiti into their indigenous populations. When thesepopulations were used, Manitoban wapiti were found to be monophyletic and Rocky Mountain wapiti to be paraphyletic.However, including animals from the Canadian Rocky Mountains places Rocky Mountain wapiti in clades by themselves orgrouped with Manitoban wapiti. The clade containing a mixture of Manitoban and Rocky Mountain wapiti suggests that bothtypes recently descended from a common ancestor. Hybridization or insufficient time for separation may explain the presenceof the two types in the same clade.
Blood parasites of migrating Willow Warblers (Phylloscopus trochilus) at a stopover site
Authors: Rintamäki Pekka T , Ojanen Mikko , Pakkala Heikki , Tynjälä Matti
Published: April 2011

Populations are often difficult to separate on the basis of morphometric data. However, since blood parasites have shown significantly different prevalences and parasitaemias in natural host populations, such discrepancies may provide an opportunity of studying population differences in migrating birds. We obtained blood samples from 312 Willow Warblers (Phylloscopus trochilus) at the Tauvo Bird Observatory, Gulf of Bothnia, Finland. Approximately one-fifth of the birds were parasitized by at least one out of four different haematozoans. Most of these birds (88%) were infected with either Haemoproteus belopolskyi (Hb) or Leucocytozoon phylloscopus (Lp). These parasite species were predominant in the samples at different times, Hb earlier and Lp later. Based on tail and wing lengths, body mass, and wing length - tail length ratio, Hb-infected juvenile males were significantly larger than Lp-infected birds. Different dipteran vectors transmit these haematozoa, and in conjunction with morphological evidence, the observed difference in time of main occurrence of these two parasites may indicate that the birds had become infected in different areas. Thus, our samples may include different (sub)populations of Willow Warblers. In general, blood parasites may provide a means of differentiating among individuals originating from different areas.