bluuebunny/crossref_metadata_2025 huggingface dataset:
Tales of lizard tails: effects of tail autotomy on subsequent survival and growth of free-ranging hatchling Uta stansburiana
Authors: Niewiarowski P. H. , Congdon J. D. , Dunham A. E. , Vitt L. J. , Tinkle D. W.
Published: April 2008

Potential costs and benefits of tail autotomy in lizards have been inferred almost exclusively from experimental study in semi-natural enclosures and from indirect comparative evidence from natural populations. We present complementary evidence of the costs of tail autotomy to the lizard Uta stansburiana from detailed demographic study of a natural population. On initial capture, we broke the tails of a large sample of free-ranging hatchlings (560) and left the tails of another large sample (455) intact, and then followed subsequent hatchling growth and survival over a 3-year period. Surprisingly, in 1 out of the 3 years of study, survival of female hatchlings with broken tails exceeded that of female hatchlings with intact tails. Furthermore, no effects of tail loss on survivorship were detected for male hatchlings. However, in 2 years when recaptures were very frequent (1961, 1962), growth rates of hatchlings with broken tails were significantly slower than those of their counterparts with intact tails. We discuss our results in the broader context of estimating the relative costs and benefits of tail autotomy in natural populations, and suggest that long-term demographic studies will provide the best opportunity to assess realized fitness costs and benefits with minimum bias. We also describe how experimentally induced tail autotomy can be used as a technique to complement experimental manipulation of reproductive investment in the study of life-history trade-offs.
Trophic relationships of albatrosses associated with squid and large-mesh drift-net fisheries in the North Pacific Ocean
Authors: Gould Patrick , Ostrom Peggy , Walker William
Published: April 2008

The diets of Laysan (Diomedea immutabilis) and black-footed albatrosses (D. nigripes) killed in squid and large-mesh drift nets in the transitional zone of the North Pacific Ocean were investigated by examining the contents of the digestive tracts and determining δ13C and δ15N values in breast-muscle tissue. The results show that (i) the combined prey of the two species of albatross consists of over 46 species of marine organisms including coelenterates, arthropods, mollusks, fish, and marine mammals; (ii) both species supplement their traditional diets with food made available by commercial fishing operations (e.g., net-caught squid and offal); (iii) while obtained from drift nets, diets of nonbreeding Laysan and black-footed albatrosses are dominated by neon flying squid (Ommastrephes bartrami); (iv) in the absence of drift-net-related food, Laysan albatrosses feed most heavily on fish and black-footed albatrosses feed most heavily on squid; and (v) based on δ15N values, nonbreeding adult Laysan albatrosses from the transitional zone of the North Pacific Ocean and Laysan albatross nestlings fed by adults from Midway Island in the subtropical Pacific feed at one trophic level and one-third of a trophic level lower than black-footed albatrosses, respectively.
Fledgling care and male parental effort in the Hooded Warbler (Wilsonia citrina)
Authors: Ogden Lesley J. Evans , Stutchbury Bridget J. M.
Published: April 2008

We followed family groups of Hooded Warblers (Wilsonia citrina) from hatching through to fledgling independence to determine (i) the duration and extent of parental care of fledglings, (ii) the extent of brood division, and (iii) whether male parental effort in caring for nestlings predicts male effort in caring for fledglings. The 9-day nestling period of Hooded Warblers was followed by 4 – 6 weeks of further parental care of fledged young. Parental feeding rates increased from hatching to when the young fledged from the nest, and males fed nestlings significantly more than females did. At the fledgling stage feeding rates to fledglings were significantly higher than at the nestling stage, but there was no difference in feeding rates between the parents. Parents usually divided the brood of fledglings equally, so that each parent assumed full and exclusive care of a subset of the brood. However, many females (45%) initiated a second brood and the male assumed care of the entire first brood at the time when his mate began incubating. The proportion of feeding trips to nestlings made by the male was not predictive of his subsequent effort in the care of fledglings. Exclusion of the fledgling care period in studies of parental investment may give a biased picture of overall investment on the part of both male and female parents.
Changes in energy allocation by the predator Nephelopsis obscura exposed to differences in prey availability
Authors: Smith D. E. C. , Davies Ronald W.
Published: April 2008

Acquisition of energy and its allocation to components of bioenergetic balance were measured throughout the life cycle in three groups of Nephelopsis obscura fed one (low frequency), two (medium frequency), or three (high frequency) ad libitum meals each week at 15 and 20 °C. As feeding frequency increased, the total amounts of energy ingested, faeces plus mucus produced, somatic and reproductive growth, energy storage (total lipids), and respiration all increased. The proportion of ingested energy allocated to somatic and reproductive growth was highest for the medium-frequency and lowest for the low-frequency feeding treatment. Temperature had no effect on ingestion or faeces plus mucus production, but the respiration rate was higher and the growth rate lower at 20 than at 15 °C. The proportions of ingested energy allocated to growth and storage were the same in the high- and medium-frequency feeding treatments at both temperatures. In the low-frequency feeding treatment, the proportion of energy allocated to storage was higher at 15 °C, but proportionally more energy was allocated to somatic growth and less to reproductive growth or lipid storage at 20 °C. In the high- and medium-frequency feeding treatments, the relative amount of energy allocated to storage was constant, i.e., the ratio of reserves to structural tissues was the same, at both temperatures.
A chorus song style influences sexual responses in female canaries
Authors: Nagle L. , Kreutzer M. L. , Vallet E. M.
Published: April 2008

We examined whether the playback of a chorus song style (i.e., two songs presented simultaneously from a single speaker) influences sexual song preferences of female domesticated canaries, Serinus canaria. Six females were treated with estradiol and their responses to the different types of song were measured as the frequency of copulation solicitation displays. Females responded preferentially to a chorus song style and reacted less to presentation of single songs (conspecific and heterospecific). These observations suggest that females sexual responses are elicited by two songs heard simultaneously. Our results are discussed in relation to current views on the song preferences of females and the phenomenon of chorus singing in songbirds.
Effects of blow fly (Protocalliphora spatulata: Diptera: Calliphoridae) parasitism on the growth of nestling savannah sparrows in Alaska
Authors: Miller Clinton K. , Fair Jeanne M.
Published: April 2008

We investigated the effect of blow fly larvae (Protocalliphora spatulata) on nestling savannah sparrows (Passerculus sandwichensis) in Alaska subject to biennially fluctuating prey abundance. Grasshopper populations in some regions of interior Alaska can show a strong biennial periodicity. Growth of nestling savannah sparrows, numbers of blow fly larvae in nests and on nestlings, and grasshopper populations were monitored during four breeding seasons (1990–1993) on the Delta Agriculture Project site near Delta Junction, Alaska. Growth parameters for parasitized and nonparasitized nestlings were compared within and between years. There were no significant differences in growth parameters between parasitized and nonparasitized nestlings between any years. There were also no differences in growth parameters within years, except for tarsus length in 1991 and nestling mass in 1993 (low grasshopper years); in 1993, parasitized nestlings were heavier and the sample size was small. Additionally, there were no differences in fledging success within years. Although parasitism combined with other factors (e.g., food limitation) may have an impact on avian reproduction, our data do not support this.
Completing the life cycle: detachment of an aquatic parasite (Arrenurus cuspidator, Hydrachnellae) from an aerial host (Coenagrion puella, Odonata)
Authors: Rolff Jens , Martens Andreas
Published: April 2008

Water mites are are very important parasites of aerial stages of aquatic insects. Their larvae parasitize semiaquatic hosts and must detach while the host is in a suitable habitat for reproduction of parasite and host. Therefore, water mites should respond to stimuli indicating this situation. Different stimuli were tested experimentally in the host – parasite system Coenagrion puella – Arrenurus cuspidator in outdoor cages; this method provides exact data on the initial intensity of mite larvae per host. It was found that mites detach during tandem oviposition by the host. The detachment rate does not correlate with the host's sex or with the intensity of mite larvae per host. Ectoparasitic water mites are apparently influenced by the host's condition because mites did not detach from dead hosts even in water. Proximity to water also seems to have an impact: mites exposed at a height of 10 mm above water detached, whereas mites exposed at 25 mm or higher did not. We suggest that detachment of mite larvae is triggered by a group of stimuli associated with the egg-deposition behaviour of the host.
A taxonomic revision of the Pacific black fly subgenus Inseliellum (Diptera: Simuliidae)
Authors: Craig D. A.
Published: April 2008

The simuliid subgenus Inseliellum is revised and additional diagnostic characters are provided. This taxon, found in Guam, Truk, Cook, Austral, Marquesas, and Society islands, now comprises 40 species. Sixteen new species are described: S. bogusium, S. clibanarium, S. concludium, S. connae, S. dojeycorium, S. dussertorum, S. evenhuisi, S. fossatiae, S. jnabsium, S. lonckei, S. maraaense, S. middlemissae, S. proctorae, S. pufauense, S. rurutuense, and S. shannonae. Additional descriptions are given for most other species. A key to the larvae of Society Islands species is given. Brief comments are made concerning relationships within Inseliellum, larval habitats, and biology.
Food availability and primary feather molt in European starlings, Sturnus vulgaris
Authors: Swaddle John P. , Witter Mark S.
Published: April 2008

The effects of food quality and overall food intake on molt have been experimentally investigated in a number of species. However, little is known concerning the influence of periodic food availability on molt parameters, although there are some associations in the field. In this study, we experimentally manipulated food availability through food deprivation during the molt of adult and juvenile European starlings, Sturnus vulgaris. By monitoring molt scores, wingtip shape, and lengths and length asymmetries of primary feathers during molt, we demonstrated that food deprivation can influence molt. Food-deprived juvenile starlings exhibited slower feather growth rates, although the duration and rate of molt were not affected. There were no differences in wingtip shape between food-deprived and control birds at the end of molt for either adults or juveniles. We also observed erratic reshedding of previously molted primary feathers in juveniles, although this did not appear to be related to the experimental treatments. The results of this study imply that feather growth rates and shedding rates are differentially affected by food availability: growth rates may be decreased when food deprivation occurs, whereas shedding rates are relatively unaffected.
Time-budget variations in relation to density-dependent social interactions in female and yearling male fallow deer during the rut
Authors: Pélabon Christophe , Komers Petr E.
Published: April 2008

We investigated time-budget variations among female and yearling (socially immature 1.5-year-old) male fallow deer (Dama dama) during the rutting season in six captive populations in central Sweden. The effects of population density, male density, and operational sex ratio on time budgets were analyzed. Although no differences were apparent before the rut, populations differed in the time budgets of females and yearling males during the rut. During this period, the time spent by females in feeding and resting activities of yearling males decreased with increasing population density, whereas feeding and resting activities of yearling males decreased with increasing male density. Behaviour of adult males during the rut and interactions of adult males with other animals appeared to be the principal factors affecting the time budgets of both females and yearling males. Our results show that density-dependent effects may occur through social interactions alone, regardless of the effects on resource depletion. The decrease in the proportion of time spent in restoring (lying and grazing) behaviours represents an energy cost for both females and young males. Given the timing of the rut just before the winter, this cost may negatively effect the condition of individuals.
Histology and teratology of pink salmon larvae near the time of emergence from gravel substrate in the laboratory
Authors: Marty Gary D. , Heintz Ronald A. , Hinton David E.
Published: April 2008

During salmonid larval development, emergence from gravel substrate is a major event marked by final yolk absorption and transition to exogenous feeding. The gross and histological changes associated with this fundamental biological process were investigated in pink salmon (Oncorhynchus gorbuscha) 4 weeks before emergence (alevins), at emergence (swim-up fry), and 2 weeks after emergence with or without exogenous feeding. Larvae were derived from artificially spawned eggs reared in gravel-filled incubators in the laboratory. Less than 1% of emergent larvae had gross lesions. These included opercular hypoplasia or dysplasia (semioperculum), spinal anomalies (lordosis and kyphosis), conjoined twins, and ophthalmic dysplasia. Apoptosis, or programmed cell death, was a common cellular change, and several cell types were involved: (i) intragonadal supporting cells, (ii) gastric submucosal gland epithelial cells, and (iii) midventral skin cells. Semiquantitative scores for apoptosis were usually highest in pre-emergent larvae and lowest in postemergent larvae. Larvae that were not fed during the first 2 weeks after emergence had slightly higher scores for apoptosis and hepatocellular megalocytosis than did fed controls.
Sugar-meal sources used by female black flies (Diptera: Simuliidae): a four-habitat study
Authors: Burgin Steven G. , Hunter Fiona F.
Published: April 2008

Adult black flies were sampled by sweep-netting vegetation in four habitats within Algonquin Provincial Park, Ontario: Davies Bog, the airfield, deciduous habitat, and coniferous habitat. Sugars in the crops and midguts of female flies (n = 773) were tested by thin-layer chromatography to determine whether the flies had fed on nectar or homopteran honeydew. Melezitose and stachyose were used as honeydew-indicator sugars. For Simulium venustum, it was found that significantly fewer black flies (19%) from the airfield contained honeydew sugars than black flies from the other three sites (34% from Davies Bog; 36% from deciduous habitat; 25% from coniferous habitat). We argue that black flies will feed on nectar or honeydew according to availability.
Genetic analysis of hybrid sterility in crosses of the tsetse fliesGlossina palpalis palpalisandGlossina palpalis gambiensis(Diptera: Glossinidae)
Authors: Gooding R. H.
Published: April 2008

Reciprocal crosses of Glossina palpalis gambiensis Vanderplank and Glossina palpalis palpalis (Robineau-Desvoidy) were carried out using flies that had four marker genes on the X chromosome, two in linkage group II and one in linkage group III: The results of the reciprocal crosses conformed to Haldane's rule: F1males were sterile and most F1females were fertile. F1females mated to G. p. gambiensis were more likely to be fertilized than females that were mated to G. p. palpalis. In three of the four experiments, the fertility of backcross females was not significantly different from that of F1females, and there was little evidence that specific chromosomal combinations influenced the fertility of backcross females. Intrachromosomal recombination was lower in hybrid females than in G. p. palpalis. The major genetic factor associated with sterility among backcross males was the presence of sex chromosomes from two subspecies; a minor factor was the number of heterozygous autosomes, but interactions between sex chromosomes and autosomes from different taxa did not contribute to hybrid male sterility. Evidence is presented that a major factor causing hybrid male sterility lies between the loci tan (an eye color) and Est-t (testicular esterase) on the X chromosome. The use of differences between the fertility of males produced by backcrossing F1females to the two parental subspecies as indicators that other X chromosome loci have a role in hybrid sterility is discussed.
Grazing strategies of muskoxen (Ovibos moschatus) during winter in Angujaartorfiup Nunaa in western Greenland
Authors: Nellemann Christian
Published: April 2008

Terrain and vegetation use by muskoxen (Ovibos moschatus) during winter was examined through surveys of fecal pellet groups in western Greenland in 1994. Being virtually free of snow, Kobresia myosuroides steppe and dry and moist shrub heath were used extensively by muskoxen. Use varied among the three heath vegetation types in relation to the proportion of shrubs to graminoids, with most use being made of K. myosuroides steppe. Density of fecal pellet groups varied from 300 groups/ha at a graminoid biomass of ca. 30 g/m2to > 2500 groups/ha where biomass exceeded 100 g/m2. Within K. myosuroides steppe, density of fecal pellet groups was < 500 groups/ha on narrow ridges compared with > 2000 groups/ha on wider steppe formations. Adaptation by muskoxen to grazing steppe-like vegetation throughout the Late Pleistocene may explain the extraordinarily rapid growth of the population in this grass steppe landscape in western Greenland.
Summer foods of Atlantic walrus,Odobenus rosmarus rosmarus, in northern Foxe Basin, Northwest Territories
Authors: Fisher K. I. , Stewart R. E. A.
Published: April 2008

Stomach contents of Atlantic walrus, Odobenus rosmarus rosmarus, taken by Inuit hunters in northern Foxe Basin in July 1987 and 1988 (n = 105) and September 1988 (n = 2) were examined. In July, 20 of 94 stomachs from immature and adult walrus contained > 5 g of food representing 17 prey taxa, including bivalves, gastropods, holothurians, polychaetes, and brachiopods. The bivalve Mya truncata contributed 81.4% of the total gross energy in the diet, with the bivalve Hiatella arctica, holothurians, and the polychaete Nereis sp. contributing 7.5, 3.5, and 2.8%, respectively. The diets of male and female walrus were similar except that females received a significantly (P < 0.05) greater percentage of gross energy in their diet from H. arctica than did males. Walrus less than 3 years old (n = 11) consumed mostly milk, although some benthic invertebrates were eaten. Analysis of the contents of two stomachs collected in September suggested that walrus may feed more intensively in the fall. Mya truncata was again the predominant prey, contributing 59.9% of total gross energy, with the bivalve Serripes groenlandicus (37.9%) replacing H. arctica (0.3%) as the second most important prey.
Line-transect sampling for estimating ptarmigan (Lagopus spp.) density
Authors: Pelletier Luc , Krebs Charles J.
Published: April 2008

Current methods of estimating ptarmigan density require total counts, and hardly apply to areas exceeding 1 km2. We evaluated the applicability, accuracy, and efficiency of line-transect sampling as an alternative method for estimating breeding density of male ptarmigan. We compared Hayne's and generalized Hayne's estimators with line-transect estimators based on perpendicular distance. We surveyed 6 subalpine areas in Kluane, Yukon, with 231 km of transects in 1995 and 1996, in addition to a 77-ha grid where we also conducted total counts. Estimates of perpendicular distance were accurate (bias = −3 to −7%). Their efficiency resides mainly in detecting changes in density over 2-year periods in highly or moderately fluctuating populations. Performance of Hayne's estimator was close to that of perpendicular distance (coefficient of correlation, r = 0.95), even if in many cases the average sighting angle was not 32.7°. The generalized Hayne's estimator was not robust; biases were up to −90%. The results of this survey, with densities ranging between 0 and 65 males/km2 for similar and adjoining subalpine areas, dispute the principle that the "health" of a population can be assessed by censusing only a small area.
Age-related changes in the biliary bile acid composition of bovids
Authors: Hagey Lee R. , Gavrilkina Miriam A. , Hofmann Alan F.
Published: April 2008

The biliary bile acid composition of 12 tribes of bovids (66 species, 168 animals) was determined by high-performance liquid chromatography and mass spectrometry. In adult animals, the biliary bile acids were conjugated with taurine or glycine and consisted mostly (> 90%) of three bile acids: cholic acid (CA), chenodeoxycholic acid (CDCA), and deoxycholic acid (DCA). Biliary bile acid composition did not vary among species, and was identical in male and female bovids. Within each species, there were consistent changes in biliary bile acid composition with age. Three steady-state stages could be distinguished: (1) the fetal stage, when bile acid input is from placental transfer from the mother as well as biosynthesis (from cholesterol) by the newborn liver (45 ± 12% CA; 50 ± 11% CDCA; 5 ± 4% DCA (mean ± SD)); (2) the infant stage, when bile acid input is solely from biosynthesis by the infant liver (80 ± 6% CA; 20 ± 6% CDCA; 0.5 ± 0.7% DCA); and (3) the adult stage, when bile acid input is not only from biosynthesis by the adult liver but also from intestinal absorption of DCA, formed by bacterial 7-dehydroxylation of CA (75 ± 12% CA; 6 ± 7% CDCA; 19 ± 9% DCA). The transition from the infant stage to the adult stage, indicating the development of an anerobic cecum, occurred before weaning. These three stages of biliary bile acid composition are likely to be present in other placental vertebrates, including most primates, in whom a cecum containing an anerobic flora develops after birth; the functional implications of these changes are discussed.
Ontogenetic diet shifts in age-0 striped bass, Morone saxatilis, from the Miramichi River estuary, Gulf of St. Lawrence
Authors: Robichaud-LeBlanc Kimberly A. , Courtenay Simon C. , Hanson J. Mark
Published: April 2008

Stomach contents of 2928 age-0 striped bass, Morone saxatilis (2.9–153.3 mm total length (TL)), collected from June to November 1992 in the Miramichi River estuary were examined. Seventy-seven percent of the fish stomachs examined contained food organisms and 34 prey taxa were identified. Larval striped bass (< 25 mm TL) fed primarily on immature and adult copepods. The onset of exogenous feeding correlated both spatially and temporally with a peak in the abundance of prey. Chesson's α index indicated progressive selection of larger prey with increasing size of larval striped bass, from small rotifers to larger calanoid copepods to the relatively large calanoid Eurytemora sp. Mysids (Neomysis americand) and sand shrimp (Crangon septemspinosa) were the principal prey of striped bass > 50 mm TL. Contributions by other prey groups (molluscs, polychaetes, amphipods, insects, and larval fish) were minor. Large underyearlings, 64–84 mm TL, in near-fresh water ate proportionally more mysids than fish downriver in more saline waters. Feeding ceased when water temperatures declined below about 3 °C in November.
Effects of polyunsaturated fatty acids and some of their metabolites on mitotic activity of vascular smooth muscle explants from the coronary artery of rainbow trout (Oncorhynchus mykiss)
Authors: Gong B. , Townley R. , Farrell A. P.
Published: April 2008

This study is the first to examine the effects of polyunsaturated fatty acids and some of their metabolites on [3H]thymidine incorporation into vascular smooth muscle explants from the coronary artery of rainbow trout (Oncorhynchus mykiss). At a concentration of 120 μM, eicosapentaenoic acid (EPA; 20:5ω3), arachidonic acid (AA; 20:4ω6), and eicosatrienoic acid (ETA; 20:3ω6) all approximately doubled [3H]thymidine incorporation relative to controls. At a concentration of 20 μM, EPA had no significant effect, while ETA inhibited and AA caused an almost 5-fold increase in [3H]thymidine incorporation. The large mitogenic effect of 20 μM AA was completely inhibited by simultaneous addition of EPA to the culture medium. ETA only partially inhibited the mitogenic effect of 20 μM AA. Four AA-derived eicosanoids (or their stable analogues) were also tested. [3H]Thymidine incorporation was at least doubled with 1000 ng/mL carbacyclin (a prostacyclin analogue), 120 ng/mL prostaglandin F2α, and U-46619 (a thromboxane A2 analogue), but did not reach the level of stimulation produced by 20 μM AA. Leukotriene C4 had no significant effect. We conclude that dietary modulation of polyunsaturated fatty acids (PUFAs) in salmonids could have significant effects on coronary vascular smooth muscle mitosis through the incorporation of PUFAs into cell membranes and the production of eicosanoids.
Food cache recovery by Northwestern Crows (Corvus caurinus)
Authors: Verbeek N. A. M.
Published: April 2008

This field study examined experimentally whether Northwestern Crows (Corvus caurinus) used random search or memory to relocate food caches. The crows cached food items in the ground, one per cache, and covered the cache before leaving the site. Most caches were recovered within 24 h. The crows found caches made by me 1 m from their own caches significantly less often than they found their own caches. Replacing the covering of the cache with material other than the crows used did not significantly affect recovery success, but the crows found significantly fewer of their caches when the latter were experimentally moved 15 cm. Adding a 25 cm long stick to the site 15 cm from the cache significantly decreased a crow's ability to relocate its cache, but not when it was placed 30 cm away. A 50 cm long stick placed 15 or 30 cm away had the same negative effect on a crow's ability to relocate its cache, but not when it was placed 45 cm away. When memory is used, recovery success can be as high as 99%; when random search is used, it can be as low as 6%.
The effect of strain of donor eggs, culture conditions, and experimental protocol on release of eggshell calcium by the chick chorioallantoic membrane in vitro
Authors: Packard Mary J.
Published: April 2008

Factors affecting release of calcium by the chick chorioallantoic membrane in vitro were assessed by culturing explants of shell with and without the chorioallantoic epithelium. Explants were removed from eggs on day 16 of incubation and cultured using techniques similar to those used to examine resorption of bone in vitro. The region of an egg from which an explant is removed, the strain of donor eggs used, and addition of bovine serum albumin to the culture medium did not affect release of calcium. In contrast, exposure of explants to a variety of different culture media (DMEM, Medium 199, BGJb, and RPMI) introduced considerable variation in calcium release. Calcium release in vitro was also examined by removing the blunt end of a fertile egg as well as the embryo and yolk. The remaining preparation was filled with culture medium, covered, and cultured for two 24-h periods, with a change of medium after the first 24 h. Preparations from which the chorioallantoic membrane had been removed released very little calcium during culture, whereas those with the epithelium in place released considerable quantities. However, release of calcium by preparations with the membrane declined during the second interval. When surface area is taken into account, such preparations mobilize less calcium than explants cultured under similar conditions.
Evaluation of the urinary allantoin:creatinine ratio as a nutritional index for elk
Authors: Garrott Robert A. , Cook John G. , Berardinelli James G. , White P. J. , Cherry Steve , Vagnoni David B.
Published: April 2008

We conducted experiments with captive female elk (Cervus elaphus) to explore the utility of allantoin:creatinine (A:C) ratios as a noninvasive index of nutrition in free-ranging ungulates. Pens of animals were assigned to one of four dietary treatments, each treatment being given to 6 animals. One treatment involved gradually increasing the daily metabolizable energy intake (MEI) from approximately 650 to 1200 kJ metabolizable energy (ME)/kg body mass (BM)0.75in weekly increments over 8 weeks. In a second treatment, daily MEI was decreased in a similar manner from approximately 900 to 250 kJ ME/kg BM0.75. Urine samples (96 in total) were collected from each animal in these treatments 5 days after each change in diet. Two additional treatments involved relatively large and abrupt changes in daily diet ranging from 120 to 500 kJ ME/kg BM0.75, with successive diets being alternately increased and decreased at 2-week intervals for 10 weeks. Urine samples (179 in total) were collected from each animal 3, 5, and 13 days after a dietary change was initiated. The underlying relation between A:C ratio and MEI was consistent among the four treatments and indicated that the urinary A:C ratio is a reliable index of dietary intake in elk across a variety of dietary regimes. A:C ratios responded relatively quickly to changes in diet, indexing the dietary intake of the animals during a several-day period immediately prior to the time the urine was voided. The results of this and previous studies indicate that the urinary A:C ratio has significant potential as a nutritional index for wild ruminants; however, we recommend additional research before the use of A:C ratios is integrated into ecological or management applications.
Relationships among problematic North American stagnicoline snails (Pulmonata: Lymnaeidae) reinvestigated using nuclear ribosomal DNA internal transcribed spacer sequences
Authors: Remigio E. A. , Blair D.
Published: April 2008

The taxonomic relationships among four stagnicoline snail species from North America were reassessed by analysing nucleotide sequences from their nuclear ribosomal internal transcribed spacer (ITS) region. Three of the species (Stagnicola catascopium, Stagnicola emarginata, and Stagnicola elodes) are representatives of the subgenus Stagnicola s.str. from the northern U.S.A. and the fourth is a closely related Canadian species (Stagnicola caperata) belonging to the subgenus Hinkleyia. Members of the two subgenera differed considerably in their ITS sequences, demonstrating the usefulness of these sequences for distinguishing species from closely related lymnaeid subgenera. In contrast, ITS sequences for the three members of the subgenus Stagnicola s.str. were very similar, which supports an earlier view that they may not be separate species.
Geographical displacement and timing of molt of the remiges in male Wood Ducks
Authors: Vrtiska Mark P. , Kaminski Richard M. , Prince Harold H. , Thompson John D.
Published: April 2008

Captive wild-strain male Wood Ducks, Aix sponsa, reared in Mississippi and transported to Michigan and Illinois in 1993 and 1994 were used to test the effect of geographical displacement and age on timing of molt of the remiges. Males transported to both northern sites initiated remex molt later (P = 0.0001) in 1993 than males remaining in Mississippi. In 1994, males continued to molt later at northern sites than in Mississippi, but earlier molting at both northern sites in 1994 than in 1993 resulted in no detectable differences (P = 0.31) in molting date. Although there were no differences (P > 0.05) in date of remex molt between adult and yearling males in 1992 and 1993, molt occurred earlier (P = 0.0006) each year for birds remaining in Mississippi during 1992–1994. Timing of remex molt in male Wood Ducks may be influenced by photoperiodic, environmental, and social cues associated with geographical displacement, but other factors (e.g., genetics) may also influence annual timing.
Influence of diet on survivorship and growth inPortia fimbriata, an araneophagic jumping spider (Araneae: Salticidae)
Authors: Li Daiqin , Jackson Robert R.
Published: April 2008

The influence of diet on survival rate and growth was investigated in Portia fimbriata, an araneophagic salticid spider in Queensland. Portia fimbriata spiderlings were reared on one of three different diets: spiders only, insects only, and a mixture of spiders and insects. For each diet, various spider and insect species were used, and the spider diets included as prey both cursorial salticid species and web-building species. Individuals on the insects-only diet did not survive past the fifth instar, whereas juveniles reached maturity when raised on the other diets. Survivorship of P. fimbriata raised on the spiders-only diet was significantly higher when they were fed on the mixed diet. Diet treatment had a significant effect on body dimensions measured at the fourth instar and at maturity. In addition, P. fimbriata reared on the spiders-only diet reached sexual maturity earlier than those reared on the mixed diet. These results suggest that there are fitness-related consequences of prey specialization in P. fimbriata.
Effects of weather and parasitic insects on behavior and group dynamics of caribou of the Delta Herd, Alaska
Authors: Mörschel Frank M. , Klein David R.
Published: April 2008

The influence of weather and parasitic insects on the behavior and group dynamics of caribou (Rangifer tarandus) of the Delta Herd in the north-central Alaska Range was investigated. Data on weather, insect abundance, and caribou behavior were collected during summer in 1994 and 1995. High ambient temperature had the greatest influence on activity budgets and rates of change in activity of caribou. In the insect season, rates of activity changes and standing increased and feeding decreased with high temperature. Rates of activity changes and moving increased and feeding decreased with high temperature, even in the absence of insects. Caribou decreased feeding and increased standing in the presence of oestrid flies, and increased the rate of activity changes in the presence of mosquitoes and oestrid flies. Weather, especially high temperature, and parasitic insects, particularly oestrid flies, affected caribou mainly by decreasing foraging opportunities and increasing energy-expending activities.
An evaluation of snow-urine ratios as indices of ungulate nutritional status
Authors: White P. J. , Garrott Robert A. , Heisey Dennis M.
Published: April 2008

We monitored trends in urea nitrogen: creatinine (UN:C), cortisol:creatinine (Co:C), and allantoin:creatinine (A:C) ratios of snow-urine samples from 5 free-ranging female elk (Cervus elaphus) in Yellowstone National Park over a three-winter period to determine their potential as indices of nutrition or nutritional stress. UN:C ratios indicated that elk were nutritionally deprived during winter, but values did not vary significantly among winters despite interannual differences in winter severity inferred from snowpack measurements and declines in calf:cow ratios. The UN:C ratio appears to be an insensitive indicator of nutritional stress over a wide range of nutritional conditions. Co:C ratios demonstrated a significantly different linear trend during each winter, but we were unable to interpret these trends because they were not related to interannual differences in indices of nutritional stress. A:C ratios demonstrated a consistent, seasonal, parabolic pattern of nutrition, with lower values occurring in midwinter and higher values in December and April. There was also a significant year effect, with lower values occurring during the hardest winter and higher values during the mildest winter. Hence, trends in A:C ratios were sensitive, interpretable, and consistent with variations in winter severity and digestible energy intake, suggesting that this metabolite warrants further scrutiny.
Relative body sizes of neonatal marine mammals
Authors: Webb Peter I.
Published: April 2008

I compared relative neonatal body masses of cetaceans and pinnipeds with those of terrestrial mammal groups. At any given adult body mass, neonatal mass was greater in cetaceans than in any other order (including pinnipeds) and neonatal mass was greater in pinnipeds than in fissipeds. I propose a number of alternative or complementary explanations for these differences.
Vocal solicitation of heat as an integral component of the developing thermoregulatory system in young domestic chickens
Authors: Bugden Shawn C. , Evans Roger M.
Published: April 2008

Young domestic chickens (Gallus gallus) were able to regulate their body temperature in a laboratory setting, where vocalizations triggered a period of rewarming (35 °C) in an otherwise cold environment. Vocal solicitation of a rewarming period functioned in an analogous manner to the parental brooding response to a vocalizing chick. The number of vocally generated rewarming bouts increased if the cold-challenge temperature was decreased from 20 to 5 °C. The body temperature and ambient temperature maintained during vocal regulation were not significantly affected by the cold-challenge temperature. Thermoregulatory reliance on vocally induced rewarming bouts decreased with age as endothermic capability and the ability to retain heat improved. This decreased reliance on vocally induced heat inputs matches the pattern of decline of parental brooding seen in chicks reared in a natural setting. Body temperature at both cold-challenge temperatures increased with age, while the preferred ambient temperature decreased with age. This pattern is also found in the young of many birds species tested in spatial thermal gradients. Vocal solicitation of heat thus appears to form an integral and finely tuned part of the overall thermoregulatory system of these young precocial birds.
Individual responses to predation risk and food density in perch (Perca fluviatilisL.)
Authors: Utne A. C. W. , Brännäs E. , Magnhagen C.
Published: April 2008

Perch, Perca fluviatilis, of different sizes and ages were allowed to choose between two feeding patches differing in food ratio and (or) predation risk (presence versus absence of a pike, Esox lucius). The aim of our study was to test whether food-patch choice and risk-taking behaviour (time with the predator present) were related to size, phenotype (fast- versus slow-growing) and (or) stage of development (mature versus immature). Movements of individual fish were continuously monitored with an automatic system employing passive integrated transponder (PIT) tags. Food distribution did not seem to be important in determining perch distribution. Predation risk, however, had a significant influence. The presence of a predator in a patch significantly reduced the proportion of time spent in that feeding patch by all perch. However, the strength of this effect was dependent on individual characteristics, both the slow-growing phenotype and the mature fish spending a significantly lower proportion of time in the risky patch than the fast-growing and immature fish. Switching rates, which differed between character groups, also had an effect on growth rate, varying with predation risk.
Biogeographic and evolutionary implications of size variation in North American least weasels (Mustela nivalis)
Authors: Reig Santiago
Published: April 2008

Geographic variation in the skulls of least weasels, Mustela nivalis, from North America, Central Europe, and Siberia was investigated to determine the influence of environmental variation and recent biogeographic history. The clustering pattern of 16 populations, based on overall morphological similarity, revealed the existence of four large groups, which were assigned to the subspecies rixosa, eskimo, vulgaris, and subpalmata, each associated with a specific geographic area and showing a distinct degree of sexual dimorphism. Variation in size was not associated with these four groups. Variation in degree of sexual dimorphism was less within each of these groups than among them, despite considerable environmental changes, suggesting that ecological factors are not significant. Relative to M. erminea, which was used as the outgroup, M. subpalmata constitutes a very distinct taxon that deserves consideration as a separate species. The eskimo and rixosa groups, though differing in size, still show large differences in shape that cannot be explained by simple isometric or allometric size gradients of variation. Isolation of the North American fauna during the glaciations, rather than ecological factors, seems to be the key factor determining differences between the eskimo and rixosa populations. This suggests that M. rixosa should be considered a valid species.
Effect of recycling temperature on the infectivity of entomopathogenic nematodes
Authors: Jagdale Ganpat B. , Gordon Roger
Published: April 2008

Four strains of entomopathogenic nematodes were recycled in vivo for 2 years at temperatures ranging from 10 to 25 °C, then the infectivity of their infective juveniles was compared. Infectivity was examined by measuring LC50 values for wax moth (Galleria mellonella) larvae at bioassay temperatures ranging from 5 to 25 °C. Of the four strains examined, only the Umeå and NF strains of Steinernema feltiae that had been recycled at 10 °C infected and killed the insects at a bioassay temperature of 5 °C. The Steinernema carpocapsae All and Steinernema riobravis TX strains were infective at 10 °C only when the recycling temperature was ≤ 20 °C. The infectivity of the two strains of S. feltiae at 10 or 15 °C was compromised by propagating them at higher temperatures (20–25 °C). The Umeå strain of S. feltiae displayed an impaired capacity to infect hosts at higher temperatures (20–25 °C) when recycled at lower (≤ 15 °C) temperatures. The capacity of these nematodes to adjust to different recycling temperatures is discussed in relation to their infectivity in different field situations.
Facultative storage of spermatozoa by the female Geoffroy's horseshoe bat (Rhinolophus clivosus)
Authors: Wessels K. J. , Merwe M. van der
Published: April 2008

The winter breeding biology of Rhinolophus clivosus on the Gauteng Highveld, South Africa (25°S), was investigated. In contrast with a previous study in Natal (29°S), spermatozoa were not found to be stored in the uterine lumen and glands, since the spermatozoa were phagocytosed by polymorphonuclear leucocytes in the uterus. Only 25% of the females collected contained spermatozoa in their uterotubal junctions and oviducts, where the spermatozoa were oriented towards the epithelium with their heads parallel to one another, an arrangement that is characteristic of sperm-storage sites. The uteri of 66% of the females were infiltrated by large numbers of polymorphonuclear leucocytes, most probably in response to recent inseminations. The results indicate that only 25% of the females retained spermatozoa in their reproductive tracts for an undetermined length of time, whereas 66% of the females were most likely inseminated but did not store spermatozoa for the duration of the winter (May to August). In contrast with R. clivosus in Natal, females of this species on the Gauteng Highveld do not uniformly store spermatozoa for prolonged periods and sperm storage seems to be the responsibility of the males. This illustrates the divergent geographic variability in the reproduction of this species.
DESIGN AND IMPLEMENTATION OF A FOVEAL PROJECTION DISPLAY
Authors: AHLBORN BENJAMIN A. , KREYLOS OLIVER , SHAFII SOHAIL , HAMANN BERND , STAADT OLIVER G.
Published: April 2008

We introduce a system that adds a foveal inset to large-scale projection displays. The effective resolution of the foveal inset projection is higher than the original display resolution, allowing the user to see more details and finer features in large data sets. The foveal inset is generated by projecting a high-resolution image onto a mirror mounted on a panCtilt unit that is controlled by the user with a laser pointer. Our implementation is based on Chromium and supports many OpenGL applications without modifications.We present experimental results using high-resolution image data from medical imaging and aerial photography.
THE DYADIC LIFTING SCHEMES AND THE DENOISING OF DIGITAL IMAGES
Authors: TÜRÜKI TURGHUNJAN ABDUKIRIM , HUSSAIN MUHAMMAD , NIIJIMA KOICHI , TAKANO SHIGERU
Published: April 2008

The dyadic lifting schemes, which generalize Sweldens lifting schemes, have been proposed for custom-design of dyadic and bi-orthogonal wavelets and their duals. Starting with dyadic wavelets and exploiting the control provided in the form of free parameters, one can custom-design dyadic as well as bi-orthogonal wavelets adapted to a particular application. To validate the usefulness of the schemes, two construction methods have been proposed for designing dyadic wavelet filters with higher number of vanishing moments; using these design techniques, spline dyadic wavelet filters have been custom-designed for denoising of digital images, which exhibit enhanced denoising effects.
ON THE COMPUTATION OF GRAMIAN MATRICES FOR REFINABLE BASES ON THE INTERVAL
Authors: PRIMBS MIRIAM
Published: April 2008

In this paper, we discuss a simple method for the numerical computation of Gramian matrices, that appears within the construction of multiresolution analysis on the interval. The presented approach covers all, the orthogonal, the semiorthogonal and the biorthogonal cases. We consider constructions, which are based on translates of a known pair of compactly supported functions ϕ,[Formula: see text] inside the interval, and supplemented by boundary functions. Using the given two-scale-coefficients of these boundary functions, we can reduce the problem to a linear system of equations. Furthermore, we discuss conditions providing that these systems are uniquely solvable. In particular, no integrals have to be computed numerically. Finally, using the Schoenberg spline basis on the interval as an example, we show how to apply the method to a well-known problem.
DEPTH ESTIMATION USING MULTIWAVELET ANALYSIS BASED STEREO VISION APPROACH
Authors: BHATTI ASIM , NAHAVANDI SAEID
Published: April 2008

The problem of dimensional defects in aluminum die-casting is widespread throughout the foundry industry and their detection is of paramount importance in maintaining product quality. Due to the unpredictable factory environment and metallic, with highly reflective, nature of aluminum die-castings, it is extremely hard to estimate true dimensionality of the die-casting, autonomously. In this work, we propose a novel robust 3D reconstruction algorithm capable of reconstructing dimensionally accurate 3D depth models of the aluminum die-castings. The developed system is very simple and cost effective as it consists of only a stereo camera pair and a simple fluorescent light. The developed system is capable of estimating surface depths within the tolerance of 1.5 mm. Moreover, the system is invariant to illuminative variations and orientation of the objects in the input image space, which makes the developed system highly robust. Due to its hardware simplicity and robustness, it can be implemented in different factory environments without a significant change in the setup.