Growth and Dispersal of an Erupting Large Herbivore Population in Northern Canada: The Mackenzie Wood Bison (Bison bison athabascae)

In 1973, 18 wood bison (Bison bison athabascae) were introduced to the Mackenzie Bison Sanctuary. The population has grown at a mean exponential rate of r = 0.215 ± 0.007, reaching 1718 bison >= 10 months of age by April 1987. Analysis of annual population growth revealed a maximum exponential rate of r = 0.267 in 1975, followed by a declining rate, reaching a low value of r = 0.013 in 1987. Selection predation on calves was proposed as a mechanism to explain the declining rate of population growth. The area occupied by the population increased at an exponential rate of 0.228 ± 0.017 sq km/yr. The dispersal of mature males followed a pattern described as an innate process, while dispersal of females and juveniles exhibited characteristics of pressure-threshold dispersal.

Population Dynamics, Winter Ecology and Social Organization of Coats Island Caribou

The indigenous caribou population of Coats Island, N.W.T., suffered major declines from winter mortality in the winters of 1974-75 (a 71% loss) and 1979-80. There was a minor die-off in the winter of 1983-84. Apparently in the major declines the entire calf cohorts (1974 and 1979) died. In the less drastic decline in 1983-84 males, calves and adults, died at greater rates than females. The over-winter losses occurred at different densities and hence were density independent, resulting from snow accumulation and a sparse food supply. Reproductive success was low following severe winters, with 3.7% calves in June 1975 and 8.5% in June 1980. In other years, despite poor winter nutrition, the herd was productive: fall calf: cow ratios of 76:100 in 1981, 57:100 in 1982 and 102:100 in 1983. Apparently cows that survived winter starvation were able to recover despite a short growing season, in the absence of insect and predation influences, and to conceive the following autumn. High summer calf survival in the absence of predation, plus the high proportion of cows in the herd (83%), provided the means for rapid recovery in numbers (r=0.21) when winter conditions ameliorated sufficiently that starvation did not occur.Key words: island caribou, winter mortality, population regulation, social organizationMots clés: caribou des îles, mortalité hivernale, contrôle de la population, organisation social

The Hitchin functionals and the topological B-model at one loop

The quantization in quadratic order of the Hitchin functional, which defines by critical points a Calabi-Yau structure on a six-dimensional manifold, is performed. The conjectured relation between the topological B-model and the Hitchin functional is studied at one loop. It is found that the genus one free energy of the topological B-model disagrees with the one-loop free energy of the minimal Hitchin functional. However, the topological B-model does agree at one-loop order with the extended Hitchin functional, which also defines by critical points a generalized Calabi-Yau structure. The dependence of the one-loop result on a background metric is studied, and a gravitational anomaly is found for both the B-model and the extended Hitchin model. The anomaly reduces to a volume-dependent factor if one computes for only Ricci-flat Kahler metrics.Comment: 33 pages, LaTe

Analysis of pre-weaning feeding policies and other risk factors influencing growth rates in calves on 11 commercial dairy farms

Growth rates in pre-weaned calves influence their health, age at first calving and lifetime productivity. Many farms restrict milk rations to encourage solid feed intake and facilitate early weaning, but this can compromise growth. This study determined the milk feeding policies and associated growth rates on 11 commercial dairy farms in South East England, each following their normal management regime. Between 26 and 54 heifers were recruited per farm, providing a final cohort of 492, of which 71% were pure Holstein. Information on calf rearing practices (feeding, weaning, housing) and health was collected via questionnaires and weekly observations. Estimates of actual milk fed (kg solids) between 1 and 63 days were calculated for individual calves. Morphometric data (weight, height, length) were taken at weeks 1, 5 and 9 and at a median age of 7.5 months and growth rates were calculated. Most calves were fed milk replacer via automated feeders (four farms), teat feeder (one) or buckets (four) whereas two farms provided drums of acidified waste milk. Farms fed between 4 and 6 l/day of milk at mixing rates of 10% to 15%, providing 400 to 900 g/day of milk solids. Both skeletal growth rates and average daily weight gain (ADG) increased in the second month of life compared with the first: height growth from 0.17±0.14 to 0.25±0.16 cm/day and ADG from 0.48±0.25 to 0.71±0.28 kg/day. Post-weaning heifers up to 7.5 months had height increases of 0.16±0.035 cm/day and ADG of 0.83±0.16 kg/day. From 1 to 63 days 70% of calves had growth rates <0.7 kg/day and of these 19.6% gained <0.5 kg/day. Mean ADG before 9 weeks varied between farms from 0.52±0.30 to 0.75±0.20 kg/day. This was related to the amount of milk fed at both a farm and individual calf level. Increasing the total milk solids fed between 1 and 63 days from 20.4 to 46.3 kg (the 10th to 90th percentile observed) was associated with an increase of 0.11 kg/day ADG. All farms had a wide variation in growth rates despite single feeding policies. Higher circulating immunoglobulin G and IGF1 concentrations were associated with better growth, whereas low temperatures in month of birth, high scores for diarrhoea, respiratory and umbilical disease and large birth size reduced growth. Many commercially grown dairy heifers therefore experienced growth restriction in the pre-weaned period, potentially reducing their health, welfare and productivity

Search for heavy long-lived charged R-hadrons with the ATLAS detector in 3.2 fb(-1) of proton-proton collision data at root s=13 TeV

A search for heavy long-lived charged R-hadrons is reported using a data sample corresponding to 3.2 fb−1 of proton–proton collisions at √s = 13 TeV collected by the ATLAS experiment at the Large Hadron Collider at CERN. The search is based on observables related to large ionisation losses and slow propagation velocities, which are signatures of heavy charged particles travelling significantly slower than the speed of light. No significant deviations from the expected background are observed. Upper limits at 95% confidence level are provided on the production cross section of long-lived R-hadrons in the mass range from 600 GeV to 2000 GeV and gluino, bottom and top squark masses are excluded up to 1580 GeV, 805 GeV and 890 GeV, respectively

Costs and benefits of straight versus tortuous migration paths for prairie rattlesnakes (Crotalus viridis viridis) in semi-natural and human-dominated landscapes

An individualâ s migration path shape should affect its fitness, because patchily distributed features (e.g. prey) are encountered more often on straight than tortuous paths. We hypothesized that Crotalus viridis viridis (Rafinesque, 1818) with straighter migration paths should have better body condition, because they encounter prey patches more frequently, and higher migration mortality, because they also encounter predators and hazardous human land uses more frequently, than individuals with tortuous paths. If true, then a straighter path should be favoured when the benefit (resource acquisition) outweighs the cost (mortality risk). Humans pose a significant mortality risk for migrants; thus the cost of straight-line movement should increase relative to the benefit in more human-dominated landscapes, favouring more tortuous movements. We tested these hypotheses using data on the body condition, mortality, and migration movements of 25 female rattlesnakes in one human-dominated and one semi-natural landscape. As hypothesized, we found better body condition and higher migration mortality for snakes with straighter migration paths, and that snakes followed more tortuous paths in the human-dominated landscape. Although selection for tortuous movements may reduce rates of migration mortality in human-dominated landscapes, this may ultimately contribute to population declines if poorer body condition reduces overwinter survival or reproductive success.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Towards the Development of Bitumen Carbonates: An Integrated Analysis of Grosmont Steam Pilots

The Grosmont Formation in Alberta, Canada is a highly fractured, karstified and vuggy bitumen-rich carbonate reservoir located west of and below the Athabasca oil sands deposit. The bitumen carbonate platform extends about 500 km in length and up to 150 km in width and contains an estimated 64.5 billion m3 (406.5 billion barrels) of oil. The Grosmont Formation is larger than the combined total of all other known carbonate bitumen deposits in the world. Here, we analyze early Grosmont steam pilots to improve the design of future pilots and commercial development of this massive bitumen deposit. In agreement with the conclusions of earlier analysis of these Grosmont pilots, they were reasonably successful considering the heterogeneous nature of the Grosmont Formation. Operational factors such as poor steam quality, non-optimized high injection pressures and completion issues appear to have heavily impacted recovery performances. Clearly, steam-based recovery operations have good potential for Grosmont, especially considering that it is mature commercial technology. Following an integrated analysis of early Grosmont pilots, we posit that Cyclic Steam Stimulation (CSS) using horizontal wells exhibits greater potential for the development of Grosmont carbonate, compared with Steam-Assisted Gravity Drainage technology (SAGD)