bluuebunny/crossref_metadata_2025 huggingface dataset:
Local and migratory movements of Hawaiian humpback whales tracked by satellite telemetry
Authors: Mate Bruce R , Gisiner Robert , Mobley Joseph
Published: April 2011

We examined inter-island movements and offshore migrations of six humpback whales (Megaptera novaeangliae) tagged during March and April 1995 with satellite-monitored radio tags off Kaua´i, Hawai´i. The tags transmitted 0.5-17 days ( x bar = 8.5 ± 2.7 days) and produced 1-66 locations that met our screening criteria. Total travel distances per individual ranged from 30 to 1860 km. After screening criteria were applied, satellite-acquired locations ranged from 1.8 to 3.9/day for individuals (group average 2.7/day). One adult traveled 250 km to O´ahu in 4 days. Another visited Penguin Bank and five islands (820 km) in 10 days, suggesting faster inter-island movement than had been previously thought. Three whales traveled independent, parallel courses toward the upper Gulf of Alaska on north-northeast headings. A female with a calf was the fastest: 670 km in 4.5 days (150 km/day). Two whales traveled for 14.7 and 17 days, an average speed of 110 km/day (4.5 km/h). A 4200-km migration to the upper Gulf of Alaska at that speed would take 39 days. If the fastest whale's speed was maintained on a straight course, the entire migration could be accomplished in as little time as 28 days. Based on the two longest tracks, the first third of the migration route is within 1° of magnetic north. These data represent the first route and travel speeds for humpbacks migrating from Hawai´i toward Alaska.
Northern fur seal young: interrelationships among birth size, growth, and survival
Authors: Boltnev Alexander I , York Anne E , Antonelis George A
Published: April 2011

We investigated size at birth, growth, and early survival of northern fur seals (Callorhinus ursinus) from birth to weaning at Bering Island, Russia, over 8 breeding seasons from 1982 to 1989. One thousand and thirteen fur seals (565 males and 448 females) were measured in a longitudinal study and an additional 2697 animals were measured at birth. At birth, female pups were about 10% lighter and about 3% shorter than male pups. The coefficients of variation of mass (12.5 and 12.8%) and length (4.5 and 4.7%) were similar for the two sexes. We partitioned the lactation period into four time periods: 1, the perinatal period (ages 0-10 days); 2, the early development period (ages 11-40 days); 3, the period of intensive molting (ages 41-80 days); and 4, the preweaning period (ages 81-140 days). We investigated four measures of growth: absolute growth in mass (AGM) in grams per day, absolute growth in length (AGL) in millimetres per day, relative growth in mass (RGM) as a percentage per day, and relative growth in length (RGL) as a percentage per day. For both sexes, AGM was highest during period 4 (mean = 124.8 g/day, SE = 7.4 g/day, and mean = 109.6 g/day, SE = 6.8 g/day for males and females, respectively) and AGL was highest during period 2 (mean = 3.74 mm/day, SE = 0.18 mm/day, and mean = 3.42 mm/day, SE = 0.21 mm/day for males and females, respectively). RGM (mean = 1.06%, SE = 0.09%, and mean = 1.02%, SE = 0.11% for males and females, respectively) and RGL (mean = 0.53%, SE = 0.03%, and mean = 0.50%, SE = 0.03% for males and females, respectively) were highest during period 2 for both sexes. For both sexes, growth rates were slowest during the molting period. Sexual differences were detected in AGM in period 4 and for the combined data over periods 1-3. Sexual differences in AGL were detected for the combined data over periods 1, 3, and 4 only. No sexual differences in relative growth were found. Subsequent growth in mass and length was correlated with birth size. We found the greatest annual variation during the periods when growth was fastest. Condition indices were calculated using the allometric relationship between length and mass separately for neonates and pups older than 5 days. The condition indices at birth varied significantly annually. The condition index was lowest during the molting period (3). Animals that survived for at least 40 days were larger at birth and had a higher condition index than those that did not survive. In years of moderate or high pup survival rates, survival rates were higher in animals born later in the breeding season.
Perkinsus qugwadi sp.nov. (incertae sedis), a pathogenic protozoan parasite of Japanese scallops, Patinopecten yessoensis, cultured in British Columbia, Canada
Authors: Blackbourn Janice , Bower Susan M , Meyer Gary R
Published: April 2011

The pathogenic protozoan that has caused high mortalities among cultured Japanese scallops, Patinopecten yessoensis (introduced into British Columbia in 1983), is described as a new species, Perkinsus qugwadi. As in other species in the genus Perkinsus, vegetative multiplication occurred in the intercellular spaces and haemolymph sinuses of all organs of the host. Although the morphology of all developmental stages was similar to that of other Perkinsus spp., differences were observed in the ultrastructural morphology of some organelles in the biflagellate zoospore of P. qugwadi. Also, unlike all other Perkinsus spp., P. qugwadi multiplied and was pathogenic at low temperatures (8-15°C), the development of zoospores was found to occur only within the interstitial spaces of living hosts (and only in some heavily infected juvenile scallops that were less than 50 mm in valve height), and the thioglycollate culture technique that is a diagnostic test for all previously described Perkinsus spp. was negative for P. qugwadi.
Goose droppings as food for reindeer
Authors: van der Wal René , Loonen Maarten JJE
Published: April 2011

Feeding conditions for Svalbard reindeer, Rangifer tarandus platyrhynchus, on Spitsbergen are generally poor,owing to low availability of forage. We report on coprophagy: the use of goose faeces as an alternative food source for reindeer.Fresh droppings from Barnacle Geese, Branta leucopsis, placed in a field were readily used as food by reindeer. The majorityof reindeer visiting the research area were feeding on droppings instead of plants. Moreover, experiments revealed that reindeerwere highly selective, favoring droppings containing grass fragments over those containing moss fragments. This preferencecould hardly have been based on differences in mineral content (nitrogen, phosphorus, magnesium, calcium, sodium,potassium) or energy content. However, fibre content was found to correlate negatively with the percentage of moss indroppings. Selecting grass-containing droppings would therefore provide more digestible bites. The rate of intake of droppingseasily outweighed the intake rate of forage. In total, 36% of all goose droppings in the research area were removed by reindeer.We calculated that the goose droppings eaten met the entire daily energy requirements of 68 reindeer.
The influence of body size and sex on the characteristics of harbour seal foraging trips
Authors: Thompson Paul M , Mackay Ann , Tollit Dominic J , Enderby Simon , Hammond Philip S
Published: April 2011

Most pinnipeds disperse from centralised terrestrial sites to forage at sea, but the factors that result in variation inforaging-trip characteristics remain unclear. We investigated the influence of sex and body size on the summer foraging activityof radio-tagged harbour seals (Phoca vitulina) from Scotland. Mean foraging-trip duration (range 17257 h) was stronglycorrelated with mean foraging range (range 4.355.0 km), but both were significantly shorter for females. The proportion oftime spent at sea, mean trip duration, and mean foraging range were all positively related to body size. Comparison with datafrom other study areas suggests that both environmental and endogenous factors shape foraging characteristics in this species.These sex and body size related differences in activity pattern and foraging range have important implications for themethodologies currently used to assess the population size, population energy requirements, and diet composition of coastalpinnipeds.
Persistent paramesonephric ducts (masculine uterus) in the male North American beaver (Castor canadensis)
Authors: Meier Christien , Partlow Gary D , Fisher Kenneth R , Rennie Bryan
Published: April 2011

Remnants of the paramesonephric (Müllerian) ducts can be found in the male as a uterus-like structure. Historically, these have been known as a masculine uterus. We examined the reproductive tracts of 24 male North American beaver, Castor canadensis Kuhl, obtained from trappers between 1980 and 1997 from four areas extending across Ontario. Persistent paramesonephric ducts were found in 20 of these tracts. Prevalence was not related to geographic location. Grossly, the remnant appeared as one or two thin, uterus-like tubes medial to the ducti deferentes, with or without a medial corpus lying between the ampullae. Histologically, the paramesonephric remnants resembled a normal female uterus, but the endometrium consisted primarily of amorphous extracellular matrix. Previous descriptions of the prevalence of the paramesonephric duct remnants (male uterus) in C. canadensis were found to be contradictory.
The turning- and linear-maneuvering performance of birds: the cost of efficiency for coursing insectivores
Authors: Warrick Douglas R
Published: April 2011

To examine the performance compromises necessitated by adaptations for high efficiency in flight, such as highaspect ratio wings, the flight morphology and acceleration performance of a guild of coursing aerial insectivores (swifts andswallows) were compared with those of a guild of avian generalists. Though phylogenetic non-independence made inference ofadaptation difficult, biologically significant differences in aspect ratio and acceleration performance probably exist between thetwo groups of birds. A model of aerial insectivory is presented to illustrate the performance demands of this foraging methodand the impacts of the compromises between high efficiency in sustained flight and turning- and linear-maneuveringperformance.
High incidence of infanticide by lactating females in a population of Columbian ground squirrels ( Spermophilus columbianus)
Authors: Stevens Scott D
Published: April 2011

This is the first record of cercariae of Monascus filiformis (Rudolphi, 1819) and of Chaetognatha as a secondintermediate host in the southwest Atlantic Ocean. The morphology of the sporocyst and cercaria from Nucula obliqua (Bivalvia:Nuculidae) and a full description of the metacercaria from hydromedusae are given. The life cycle of M. filiformis involves threehosts. The bivalve N. obliqua is the first intermediate host, Chaetognatha and medusae are the second intermediate hosts, and thejurel Trachurus lathami (Pisces: Carangidae) is the final host. The life cycle of M. filiformis occurs in shallow waters in theArgentine Sea and differs from Køies experimental scheme for the North Sea in the addition of planktonic invertebrates assecond intermediate hosts. The life cycle proposed here follows the general pattern given for the family Fellodistomidae.
Consistency and change in bank vole (Clethrionomys glareolus) home ranges across a decade
Authors: Karlsson A Fredric , Potapov Eugene R
Published: April 2011

Minimum distance moved (MDM) and home-range sizes were studied in overwintering bank voles (Clethrionomys glareolus) during March and April in 1985, 1986, and 1996 near Uppsala, Sweden. In 1985 and 1986, the average snow depth was 50 and 35 cm in March and 7 and 18 cm in April, respectively. In 1996 the snow depth was only 16 cm in March and 2 cm in April. Bank voles were found to have winter nests at exactly the same grid coordinates in 1985, 1986, and 1996. Among females there was a high degree of consistency in home-range sizes, both between months and between years. Daily MDM of females was shorter in March 1996 than in 1985 and 1986, while no significant difference occurred during April. Males' home-range sizes, on the other hand, increased significantly from March to April in all 3 years, i.e., at the onset of the mating period. There was no significant difference in males' home-range sizes in March across years, but in April, home ranges were significantly larger 1985 and 1986 than in 1996. Males' average home-range sizes in April showed a positive correlation with snow depth. MDM of males in both March and April was also significantly higher during the snowy years of 1985 and 1986 than in 1996, when there was much less snow. These observations suggest that adequate snow cover is a favourable factor, allowing the males to expand their home ranges, while lack of snow or a thin, patchy snow cover prevents them from travelling longer distances during the mating period and consequently from visiting a large number of potential mates. These differences in the behaviour of male bank voles between snow-rich and snow-poor years may offer a partial explanation of the hypothetical connection between the less severe winter conditions during the past decade and the decline in population density and cyclicity in boreal bank vole populations.
Postnatal ossification of the thoracic limb in striped dolphins (Stenella coeruleoalba) (Meyen, 1833) from the Mediterranean Sea
Authors: DiGiancamillo Mauro , Rattegni Giovanni , Podestà Michela , Cagnolaro Luigi , Cozzi Bruno , Leonardi Leo
Published: April 2011

We analyzed the thoracic limbs of 24 striped dolphins, Stenella coeruleoalba, by means of X-ray techniques. The body length of the dolphins, the number of postnatal dentine growth layers in the teeth, the degree of ossification of the hyoid bones, and development of the gonads (when available) were correlated with X-rays and used to estimate growth stages and skeletal maturity. Newborn animals showed advanced ossification centers in the humerus and at the proximal end of the radius and ulna. The proximal end of the humerus and the distal end of the radius and ulna ossify later, followed by closure of the epiphyseal plates at the proximal and distal ends of the metacarpal bones and phalanges. We identified physical maturity by epiphyseal fusion in the thoracic limb, and considered full maturity to have been attained with deposition of bone at the level of the epiphysis-metaphysis line. The results are discussed in relation to a possible new system of age determination in S. coeruleoalba.
Hypothermic tolerance in an embryonic American kestrel (Falco sparverius)
Authors: Sockman Keith W , Schwabl Hubert
Published: April 2011

Embryos of several bird species tolerate acute hypothermia. However, the extent to which it can be tolerated by wild species living under natural conditions is poorly documented. At a single American kestrel (Falco sparverius) nest 15 days into incubation, we observed a 21-h bout of egg neglect by the parents during which nest (egg) temperature averaged 12.7°C. Normal incubation patterns resumed thereafter, and one of three viable eggs hatched 32 days after incubation onset, an incubation period 2.5 days longer than the mean in this study. The nestling appeared to develop and fledge normally. Although embryonic tolerance of extended hypothermia is known to occur in some seabirds, its presence in Falconiformes has not heretofore been recorded. Embryonic hypothermic tolerance may be adaptive in species with extended periods of parental absence during incubation.
Estimating survival rates of black bears
Authors: Sorensen Vanessa A , Powell Roger A
Published: April 2011

Capture-recapture, radiotelemetry (on a monthly and a yearly basis), and age-distribution methods were used to estimate annual survival rates for black bears (Ursus americanus) in the southern Appalachians from 1981 to 1996. Using capture-recapture data, the Jolly-Seber estimator calculated the annual survival rate for all bears over all years to be 0.64 ± 0.04 (mean ± SE). Because of small sample sizes, this method did not produce yearly estimates or allow separation of the data into age or sex classes. Both the Kaplan-Meier estimator (using monthly telemetry data) and the percent survival estimator (using yearly telemetry data) computed an overall annual survival rate of 0.76 ± 0.04. Survival rates for the early years of the study (1981-1987) were significantly lower than in the late years (1988-1996). No significant difference in survival rate was detected between the sexes or among age-classes. Because it is difficult to capture and recapture large numbers of animals, radiotelemetry methods are preferable for large mammals such as black bears. If bears wear their collars for at least a year, calculating survival from yearly telemetry data provides a good estimate of bear survival. Using monthly telemetry data, however, provided the most detailed understanding of bear survival. Survival estimates produced by the age-distribution method were unreliable.
Factors influencing T3 transport into red blood cells of rainbow trout, Oncorhynchus mykiss
Authors: McLeese J M , Eales J G
Published: April 2011

We exposed rainbow trout, Oncorhynchus mykiss, to various environmental conditions known to alter thyroid function in order to determine their effects on the in vitro carrier-mediated transport rate (J) of 3,5,3prime-triiodo-L-thyronine (T3) into red blood cells (RBC). Values for J (fmol T3 transported/(106 cells · min)) were (i) increased by assay temperature from 0 to 12°C but not from 12 to 21°C, (ii) unaltered by acclimation for 14 d at 5 or 12°C, (iii) depressed by a restricted food ration (0.5% of mean body mass/d) but unaltered by 14 d of fasting, (iv) depressed by a T3 challenge created by feeding T3-supplemented food (12 ppm T3) for 14 d, and (v) depressed 10 d after transport to our laboratory. We conclude that certain conditions that alter thyroid function also alter the rate of T3 transport into trout RBC, with possible consequences for exchange of T3 between plasma and RBC.
Distribution of catecholamines in the sea scallop, Placopecten magellanicus
Authors: Smith Stephanie A , Nason Janette , Croll Roger P
Published: April 2011

Catecholamines have previously been implicated in several important physiological processes in molluscs, including reproduction, respiration, and feeding. Much of the previous research has relied upon high-performance liquid chromatography to identify and quantify the various catecholamines and pharmacological experiments to investigate their actions. In the present report, we expand upon these studies by using histochemical techniques to investigate the distribution of catecholamine-containing cells and fibres in the central nervous system and peripheral tissues of the sea scallop, Placopecten magellanicus. Strong catecholaminergic staining was present in the somata and neuropil of all major central ganglia. Catecholamines were also abundantly stained in peripheral neurones and (or) fibres in several other tissues, including the labial palps, lips, intestine, gill filaments, foot, mantle, tentacles, and gonadal integument. It is concluded that catecholamines are widespread in the tissues of the scallop and could have potential neurotransmission roles in both the central nervous system and peripheral tissues of this species.
Roe deer habitat selection in Spain: constraints on the distribution of a species
Authors: Virgós E , Tellería J L
Published: April 2011

This study analyzes the role of summer habitat selection in determining the distribution of a population of roe deer (Capreolus capreolus L.) in central Spain, where surplus individuals have emigrated from mountains to the surrounding plateaus during the last decade. The species was more abundant in the mesic mountain forests (Scots pine (Pinus sylvestris), Pyrenean oak (Quercus pyrenaica)) than in the xeric, sclerophyllous holm oak (Quercus ilex) forests of surrounding plateaus. Roe deer prefer patches occupied by brambles (Rubus spp.) and rose bushes (Rosa spp.) and patches with higher cover on pastures and moors (Erica spp. and Calluna spp.). These vegetation types are linked to moist soils in the Mediterranean zone, indicating that roe deer prefer the moister, more productive patches. Roe deer actively selected productive patches covered by leguminous shrubs (Sarothamnus, Retama) and rejected poor patches covered by Cistus ladanifer and Cistus laurifolius (two shrubs that produce chemicals toxic to other plants). Low summer primary productivity of xeric, sclerophyllous forests can explain the low abundance of roe deer in these forests. This supports the view that habitat constraints limit numbers and distribution of this Palaearctic species at the southern edge of its range.
Genetic relatedness and home-range overlap among female black bears (Ursus americanus) in northern Ontario, Canada
Authors: Schenk Anita , Obbard Martyn E , Kovacs Kit M
Published: April 2011

The degree of philopatry exhibited by females in an unhunted black bear (Ursus americanus) population occupying the Chapleau Crown Game Preserve in northern Ontario was examined. A truncated kernel estimator was used to identify home-range use. Pairs of adult females were categorized as having home ranges that had moderate overlap or low overlap or were adjacent and non-overlapping or non-adjacent and non-overlapping. Females had low overlap with 6.4 other females, on average, and moderate overlap with 1.5 females. The degree of philopatry was assessed using two methods, each of which was used in an attempt to examine home-range overlap and average genetic relatedness. Relatedness among bears was determined from DNA fingerprints, using an alkaline phosphatase labelled multilocus probe and chemiluminescence detection. The first method involved choosing the 3 oldest females in the region to represent potential matriarchs, and all neighbouring females were identified (n = 8, 8, and 11). DNA fingerprints from each matriarch were compared with those of her neighbours. Average band-sharing coefficients and relatedness estimates within the groups did not reveal patterns of close kinship. The second method involved band-sharing comparisons among pairs of females from each of the 4 home-range categories (n = 12, 57, 80, and 21). Again, no relationship between spatial proximity and average genetic relatedness (range 0.032-0.120) was suggested. The extensive home-range overlap exhibited by this population is not a consequence of natal philopatric tendencies.
Activity of flour beetles (Tribolium confusum) in the presence of feces from rats infected with rat tapeworm (Hymenolepis diminuta)
Authors: Shostak Allen W , Smyth Kerri A
Published: April 2011

We studied the attraction of flour beetles (Tribolium confusum) to feces from rats infected with the rat tapeworm, Hymenolepis diminuta. Beetles were either fed or fasted prior to each trial. During trials, beetles were tested singly or in groups and offered a choice (i) between natural baits made from fecal pellets from infected and uninfected rats or (ii) between artificial baits made from feces of uninfected rats and differing only in the presence or absence of tapeworm tissue. Fasted beetles had a strong nonspecific attraction to baits, while fed beetles tended to avoid baits. Fasted beetles also exhibited a greater ability to discriminate between control and infective baits, sometimes preferring infective baits but at other times avoiding them. Experiments with artificial baits show that at least some of the signals which beetles respond to are of parasite origin. The results suggest that the foraging behavior of beetles in the presence of rat feces is more complex than previously thought and includes the phenomena of attraction to and avoidance of feces from infected rats in situations whose parameters have yet to be identified conclusively.
Reactive and anticipatory display to deflect predatory attack to an autotomous lizard tail
Authors: Cooper, Jr. William E
Published: April 2011

Antipredation display is usually directed to predators that have been detected, but might be beneficial when predators are likely to be dangerously close, but undetected. Anticipatory display could be selectively favored if it increased the probability of escape sufficiently to outweigh the increased probability of being detected and captured by a previously unaware predator. This is especially likely if prey have adaptations permitting a high probability of escape when attacked, such as deflection of attack to dispensible parts. Deflective displays typically occur under threat of imminent attack by a predator detected within striking distance, but might also occur in circumstances reliably entailing a high risk of ambush by undetected predators, especially immediately after an animal stops following a bout of locomotion. Tail undulation was observed in the broad-headed skink (Eumeces laticeps), a lizard with a conspicuous, autotomous tail that enhances escape ability. Eumeces laticeps undulated its tail before fleeing from a looming predator and immediately after stopping in the absence of a detected predator. Undulation after stopping confirms predictions of anticipatory deflective display and contradicts alternative hypotheses. Undulation just before flight from a predator very close at hand is a form of reactive deflection.
Influence of predator odour on the feeding behaviour of the root vole (Microtus oeconomus Pallas, 1776)
Authors: Borowski Zbigniew
Published: April 2011

An experiment carried out under laboratory conditions addressed the influence exerted by the odour of a stoat, Mustela erminea Linnaeus, 1758, on the feeding behaviour of a root vole, Microtus oeconomus Pallas, 1776. Specifically, the impact of the odour on the chewing of rowan (Sorbus aucuparia) shoots and consumption of food pellets by voles that were not sexually active was observed over a 14-day period. The floors of cages with individuals from the experimental group were sprinkled daily with a distilled-water rinse from a glass clamber in which a stoat had been confined, while cages holding control individuals were sprinkled with distilled water only. The uptake of food was monitored daily by checking the degree to which shoots had been chewed, as well as the amount of food pellets consumed. Stoat odour caused a significant reduction in chewing of the shoots but did not affect the amount of food pellets eaten. There was no significant influence of the scent on body mass, which suggests that the assimilation of food was probably the same for voles in the experimental and control groups. Long-term exposure to stoat scent was not associated with changes in food consumption over time, which suggests that the voles had not become habituated to the presence of the odour over the 2-week period. It would therefore seem that the stoat scent affected the specific feeding behaviour of the voles rather than their overall consumption level.
A phylogenetic analysis of western European species of the Lasioglossum leucozonium species-group (Hymenoptera: Halictidae): sociobiological and taxonomic implications
Authors: Packer Laurence
Published: April 2011

A data matrix of 81 characters for 23 species of the subgenus Lasioglossum sensu Michener (1999) is analysed cladistically with the primary purpose of obtaining a phylogeny for western European species of the Lasioglossum leucozonium group. Outgroup taxa were chosen on the basis of published species groupings for Old World species and a phylogeny for the New World species. Outgroup resolution was poor but results for the ingroup were consistent and indicate that (i) the social behaviour recorded for L. aegyptiellum is nested within a solitary background and therefore represents an origin of sociality independent of all others within the Halictidae, (ii) the monotypic subgenus Sericohalictus is a derived member of the leucozonium species-group, and (iii) L. laevigatum is not a member of this group.
Morphology of the spermatheca, oviduct, intermediate chamber, and vagina of the adult snow crab (Chionoecetes opilio)
Authors: Sainte-Marie Guy , Sainte-Marie Bernard
Published: April 2011

The morphology of the reproductive tract of the adult female snow crab (Chionoecetes opilio) at different stages of reproductive life was examined within the framework of studies on sperm competition. Apart from an ovary and oviduct, the tract consists of an epithelium-lined spermatheca and a cuticle-lined intermediate chamber and vagina. The morphological traits of these components are markedly influenced by the degree of spermathecal loading. Several amendments to previous descriptions are necessary: (i) pouches are not a permanent feature of the spermatheca; (ii) the outer part of the spermatheca wall is a true capsule that overlies a multilayered epithelium divided into anchoring, proliferative, and secretory strata; (iii) spermathecal secretions are of the merocrine type; and (iv) the epithelium of the spermatheca is not pigmented. Tridimensional analysis revealed that the vagina connects to the intermediate chamber via a parietal opening. The intermediate chamber is a flexible structure circled dorsally by 3-5 cuticular folds that project into its lumen. The oviduct crosses the thicker terminal segment of the spermathecal epithelium with a dorsoventral incidence, to a point opposite the parietal opening of the vagina, in such a way that it delivers its contents almost directly into the intermediate chamber. Novel functional implications of these findings are hypothesized.
Implications of cytochrome b sequence variation for biogeography and conservation of the northern flying squirrels (Glaucomys sabrinus) of the Alexander Archipelago, Alaska
Authors: Demboski John R , Jacobsen Brandy K , Cook Joseph A
Published: April 2011

The Alexander Archipelago of southeast Alaska is a highly fragmented landscape that is suspected to support a relatively large number of endemic mammals. At least two subspecies of northern flying squirrels (Glaucomys sabrinus) have been recognized from the region, the endemic Prince of Wales Island flying squirrel, Glaucomys sabrinus griseifrons, and the Alaska Coast flying squirrel, G. s. zaphaeus. We examined 56 northern flying squirrels from Alaska, Washington State, and Yukon Territory, using the DNA sequence from the mitochondrial cytochrome b gene to assess geographic variation. Flying squirrels from Washington were highly divergent (7.3%) from those of Alaska and Yukon Territory. Variation among Alaska and Yukon Territory populations was minimal, but five haplotypes were found. One predominantly "mainland" haplotype was widespread throughout Alaska, one island haplotype was confined to nine islands in southeast Alaska ("Prince of Wales complex"), and three haplotypes were unique. Flying squirrels of the Prince of Wales complex appear to be neoendemics and descended from a single founder population. Mitochondrial variation, although minimal, is consistent with the continued recognition of G. s. griseifrons. Our results, in light of increased habitat fragmentation in southeast Alaska, suggest that molecular data can provide important base-line information for effective management of insular populations.
Use of visual cues in foraging by a diurnal herbivore, Belding's ground squirrel
Authors: Duncan Richard D , Jenkins Stephen H
Published: April 2011

Ground squirrels' vision has been fairly well characterized, but whether they actually use vision in foraging has not been demonstrated. Belding's ground squirrels (Spermophilus beldingi) were allowed to forage under natural conditions for experimental bait stations to test the hypothesis that they can learn to use visual cues to forage more efficiently. Bait stations with visual cues were more likely to be found, and were found more quickly, than controls. Bait stations in taller and (or) denser vegetation were less likely to be found, suggesting that the value of visual cues may change during the growing season. Visual cues can be used to increase foraging efficiency, but other cues are probably used as well.
Dispersal patterns of juvenile Townsend's ground squirrels in southwestern Idaho
Authors: Olson Gail S , Horne Beatrice Van
Published: April 2011

Understanding the effects of habitat reduction or fragmentation on animals requires some knowledge of their dispersal patterns. We used radiotelemetry to examine dispersal characteristics of 59 (37 male and 22 female) juvenile Townsend's ground squirrels (Spermophilus townsendii) on the Snake River Birds of Prey National Conservation Area in southwestern Idaho from April to June in 1993 and 1994. We tested for differences between years, sexes, and habitats in the rates and distances of dispersal. We compared the fates of dispersers and nondispersers and tested whether the direction of dispersal differed from random and whether the distribution of dispersal distances could be fitted to a two-parameter exponential function. Of the 38 animals for which dispersal status could be determined, 16 dispersed. The proportion of dispersers was greater for males than for females, but these rates did not differ by year or habitat type. We found no differences between habitats in dispersal distance. Survival rates through immergence into estivation did not differ between dispersers and nondispersers, suggesting that dispersal is not risky over the short term. Direction of dispersal did not differ from random, and the distribution of dispersal distances was adequately fitted to a truncated exponential distribution with a truncation distance of 118 m. Dispersers tended to end up in the habitat type that they started in, suggesting the possibility of habitat imprinting.
Behavioural responses and biochemical correlates in Solea solea to gradual hypoxic exposure
Authors: Via Josef Dalla , Van den Thillart Guido , Cattani Otello , Cortesi Paolo
Published: April 2011

The common sole, Solea solea, a benthic flatfish, is frequently exposed to environmental hypoxic conditions. A succession of behavioural responses to oxygen depletion can be observed. Under moderate hypoxia (80-20% air saturation) the fish reduce spontaneous activity and the scope for activity is lowered. At the onset of anaerobic metabolism (at 20% air saturation) the fish lie still on the bottom, but with increasing severity of hypoxia they start bending the body so as to lift the mouth above the bottom and to reach water layers with higher oxygen concentrations. Between 20 and 6% air saturation, the sole applies two different metabolic strategies: (i) it activates anaerobic metabolism and (ii) it depresses its metabolism below standard metabolic rate. At 5% air saturation or lower the fish swim up with burst- and panic-like movements and lose balance and swim in an uncoordinated manner (below 3%), finally remaining paralysed at the bottom. The correlation of behavioural and metabolic responses clearly shows that under unfavourable oxygen conditions, escape behaviour and burst activity are induced as a last response when other energy-saving alternatives (anaerobic metabolism and metabolic depression) seem to become insufficient.
Social influences on intergroup transfer by pine voles (Microtus pinetorum)
Authors: Solomon Nancy G , Vandenbergh John G , Sullivan, Jr. William T
Published: April 2011

Selection to obtain mating opportunities is hypothesized to be a major factor in dispersal. Thus, if individuals move to another group or switch nests to maximize their reproductive opportunities, they should move to groups or sites where they minimize competition for resources or mates and where they can find potential mates. We examined movement of pine voles (Microtus pinetorum) in an orchard habitat. Males dispersed later than females, but the two sexes showed similar patterns of movement with respect to conspecifics. Males and females immigrated to territories that contained some opposite-sex conspecifics; they also immigrated to territories without same-sex conspecifics. The latter suggests that they may avoid competitors and move to territories where an opening exists. When female breeders were removed from a social group, a replacement female arrived and began to breed relatively rapidly. In control groups where breeding females were not removed, no replacement females appeared. These results suggest that pine voles, at least females, may monitor vacancies and immigrate if a vacancy appears.
Effects of the parasitic nematode Echinomermella matsi on growth and survival of its host, the sea urchin Strongylocentrotus droebachiensis
Authors: Stien Audun
Published: April 2011

It has been suggested that the parasitic nematode Echinomermella matsi significantly affects the population dynamics of its host, the sea urchin Strongylocentrotus droebachiensis. The effects of infection on both host fecundity and host survival may be of importance. The fecundity of sea urchins is related to their size. Negative effects of infection on host growth will therefore reduce reproductive rates. I estimated the effect of infection on host growth and survival in two naturally infected wild sea urchin populations using a capture-mark-recapture approach. Infected and uninfected sea urchins were captured and marked with unique tags or recaptured seven times from June 1994 to September 1996. The increment in the diameter of marked sea urchins between captures was used to measure sea urchin growth. The effect of E. matsi infection on host growth was small. Mortality rates were estimated using survival probability models based on the methodology developed by Cormack, Jolly, and Seber. The effect of infection on host survival was pronounced, with estimated sea urchin life expectancies reduced by 33-86% by E. matsi infection. This suggests that E. matsi may affect the population dynamics of S. droebachiensis significantly through the effect on host survival.
The physiological ecology of talitrid amphipods: an update
Authors: Morritt David , Spicer John I
Published: April 2011

A review of the major advances made in the field of the physiological ecology of talitrid amphipods (Crustacea: Amphipoda: Talitridae) over the past decade is presented. The following subjects are reviewed and their implications for the invasion of land by this group discussed: water relations, the role of exosomatic water, osmotic and ionic regulation, developmental ecophysiology, trace metals, nitrogenous excretion, gas exchange and transport, and thermal relations. It is concluded that an in-depth study of physiological "services" provided by the ventral groove is needed, and that at present, our understanding of talitrid physiological ecology is still heavily dependent on semiterrestrial species. We urgently require more studies on the physiology of palustral beachfleas and euterrestrial amphipods, particularly group IV:2 species (an evolutionarily more recent group that evolved from beachflea-type progenitors), in order to redress the current imbalance.
Growth and salinity tolerance of juvenile chinook salmon (Oncorhynchus tshawytscha) from two introduced New Zealand populations
Authors: Kinnison Michael T , Unwin Martin J , Quinn Thomas P
Published: April 2011

Self-sustaining populations of chinook salmon (Oncorhynchus tshawytscha) were established in New Zealand, from a common introduction group, near the turn of the 20th century. To investigate possible population divergence over this relatively short time scale we compared size, growth, and hypersalinity tolerance of families from two populations over their first year of rearing under shared conditions. Differences in initial fry mass were consistent with egg-size differences, but there was also evidence of genetic differences in early growth rates. Size differences between the populations decreased over time and rank correlations of mean family mass with initial egg and fry masses degraded over increasing intervals to nearly zero by the end of the year. Population effects on hypersalinity tolerance were not apparent after 4, 6, or 10 months of rearing (from yolk absorption), but family effects were suggested by ANOVAs and by the existence of groups of families with seemingly different relative seasonal optima for tolerance. Thus far, investigation of juvenile traits under common environmental conditions has shown less genetic divergence between the two New Zealand populations than is suggested by the range of differences found for phenotypic traits measured on wild adults in previous investigations.
Rheotactic response of fry from beach-spawning populations of sockeye salmon: evolution after selection is relaxed
Authors: Hensleigh Jay E , Hendry Andrew P
Published: April 2011

Rheotactic response was quantified for newly emerged sockeye salmon (Oncorhynchus nerka) fry from a beach population (Pleasure Point) and from an adjacent inlet population (Cedar River). The Pleasure Point population was small in number and had been established by straying from the much larger Cedar River population no more than 13 generations previously. When tested in laboratory raceways, fry from the Cedar River population were displaced downstream in the dark but not in the light. Such behavior is typical of inlet populations and presumably reflects selection for rapid movement to rearing lakes with minimal losses to predation. Fry from the Pleasure Point population showed greater downstream displacement than the Cedar River fry. Behavioral divergence of the Pleasure Point population could not be explained by selection, because water movement was absent from the beach environment. Genetic drift appeared to be a more plausible divergence mechanism. We suggest that the rheotactic response of beach populations should reflect the founding genotypes, gene flow from other populations, and random genetic drift. The results of previously published studies on the rheotactic response of beach fry in two other lake systems qualitatively support our hypothesis.
Larval growth and development of the stonefly Pteronarcys californica (Insecta: Plecoptera) in the Crowsnest River, Alberta
Authors: Townsend G D , Pritchard G
Published: April 2011

We used head-capsule width, wing-pad length, larval recruitment, adult emergence, and MULTIFANTM analysis to determine the life history of the stonefly Pteronarcys californica in the Crowsnest River, Alberta. Embryonic development, incorporating an early diapause, accounts for approximately 1 year of the life cycle. Both sexes spend a further 4 years in the larval stage. Female larvae grow faster than males and so achieve a larger size at emergence. Extended larval recruitment leads to variation in the sizes of larvae of the same year class and probably to cohort splitting. There is a high degree of synchrony in adult emergence, perhaps as a result of a summer diapause in antepenultimate-instar larvae. These phenomena (embryonic diapause, extended larval recruitment, different growth rates of the sexes, cohort splitting, and larval diapause) are possibly typical of aquatic insects with long life cycles.
Statistical power to detect main and interactive effects on the attributes of small-mammal populations
Authors: Schauber Eric M , Edge W Daniel
Published: April 2011

Statistical power is an important consideration in the design of experiments, because resources invested in an experiment may be wasted if it is unlikely to produce statistically significant results when real effects or differences exist. Using data from toxicological experiments on seminatural populations of small mammals, we examined the power of statistical tests for main and interactive effects. Our objectives were to evaluate the efficacy of actively reducing within-treatment variation in order to increase power and compare the power provided by several response variables commonly measured in population studies. Controlling population size (N) before treatment increased power to detect effects on N but decreased power to detect effects on population growth (r). For a specified reduction in N, r provided higher power than N. Fractional measures of recruitment generally provided low power, especially when N was low (<20 animals). Power to detect an interaction of two adverse treatments depended on the magnitudes of their main effects, as well as the magnitude of interactive effects. Estimating or predicting effect size is more complex and difficult for interactive effects than for main effects. We conclude that researchers can increase the probability of detecting real effects by choosing response variables with relatively low inherent variability. However, efforts to actively reduce within-treatment variation may have unanticipated repercussions in natural systems.
Does body condition affect fecundity in a cyclic population of snowshoe hares?
Authors: Hodges Karen E , Stefan Carol I , Gillis Elizabeth A
Published: April 2011

Snowshoe hares (Lepus americanus) undergo a 10-year cycle in abundance, with cyclic changes in reproduction occurring 3 years prior to numeric changes. Reproduction may be associated with body condition, which might change with nutrition or predation pressure. We describe hare body condition (as a mass - skeletal size relationship) through a cycle in the southern Yukon from 1989 to 1996, test the effects of food and predation risk on body condition, and examine whether changes in body condition are related to cyclic reproductive changes. Hare body condition was lowest during the decline phase but rapidly improved during the low phase. Although yearling hares were in poorer condition than adults, changes in age structure cannot explain the cyclic fluctuation in condition. Food addition and predator reduction both resulted in better body condition. Body condition did not affect reproduction. The highest natality occurred when hares were in intermediate condition, while the lowest natality occurred when hares were in the best condition. Although changes in food and predation risk affect hare body condition, we found no relationship between body condition and cyclic reproductive changes. Rather, during times of nutritional deficit, female hares may maintain mass during gestation and lactation, but at a proximate cost to their offspring. Thus, inferences based on indices of condition incorporating body mass may be misleading.
Effects of sex composition of the litter on anogenital distance in California mice (Peromyscus californicus)
Authors: Cantoni Debora , Glaizot Olivier , Brown Richard E
Published: April 2011

Anogenital distance (AGD) is longer in male than in female neonatal rodents, but can be altered by the prenatal environment. The aim of this experiment was to examine the effects of the sex composition of the litter on AGD in a species with a small litter size. We found that the AGD distributions of male and female California mice, Peromyscus californicus, overlap before weaning (33 days of age), but after weaning, males have a larger AGD than females. Because AGD is significantly correlated with body mass in both males and females, we analyzed the effect of the sex composition of the litter on AGD, using ANCOVA on logarithmically transformed data, with the logarithm of body mass as the covariate. We showed that the sex composition of the litter does not affect AGD in males but has an effect on the AGD in females at birth and this effect is significant at 33 days of age. Females from litters composed of more than 75% males had a longer AGD than those born in litters composed principally of females. This study shows that intrauterine litter composition affects AGD in females of a species characterized by small litter sizes, as has been shown in rodent species with large litter sizes. Thus, AGD can be used as a predictor of masculinization of females due to intrauterine position.