598 research outputs found

    The reintroduction of boreal caribou as a conservation strategy: A long-term assessment at the southern range limit

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    Boreal caribou were extirpated from the Charlevoix region (Québec) in the 1920s because of hunting and poaching. In 1965, the Québec government initiated a caribou reintroduction program in Charlevoix. During the winters of 1966 and 1967, a total of 48 boreal caribou were captured, translocated by plane, and released within enclosures; only their offspring (82 individuals) were released in the wild. Between 1967 and 1980, a wolf control program was applied to support caribou population growth. The caribou population, however, remained relatively stable at 45–55 individuals during this period. During the 1980s, the population grew slowly at a rate of approximately 5% each year to reach a peak of 126 individuals in 1992. At that time, Bergerud & Mercer (1989) reported that the Charlevoix experiment was the only successful attempt at caribou reintroduction in the presence of predators (in North America). Afterwards, the population declined and since then it has been relatively stable at about 80 individuals. Here we reviewed the literature regarding the ecology and population dynamics of the Charlevoix caribou herd since its reintroduction, in an attempt to critically assess the value of reintroduction as a conservation tool for this species. Indeed, the Charlevoix caribou herd is now considered at very high risk of extinction mostly because of its small size, its isolation from other caribou populations, and low recruitment. The Charlevoix region has been heavily impacted by forestry activities since the early 1980s. Recent studies have indicated that these habitat modifications may have benefited populations of wolves and black bears—two predators of caribou—and that caribou range fidelity may have exposed caribou to higher predation risk via maladaptive habitat selection. As females are ageing, and females and calves suffer high predation pressure from wolves and bears respectively, we suggest that the future of this reintroduced herd is in question and that they are facing a high probability of extinction in the near future if further action is not taken

    Perte et fragmentation en forêt boréale : impacts de différents modèles de dispersion de coupe sur les communautés de mammifères et d'oiseaux

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    La perte et la fragmentation de l'habitat constituent les deux principaux types de perturbations qui influencent la biodiversité mondiale. Dans l'hémisphère nord, l'exploitation forestière commerciale génère la perte et la fragmentation du couvert forestier mature, affectant de nombreuses espèces fauniques. En forêt boréale, plusieurs travaux se sont intéressés à caractériser et quantifier les impacts des opérations forestières sur plusieurs taxons fauniques et floristiques. Maintenant que les impacts du prélèvement forestier sont mieux documentés dans cet écosystème, le défi de conservation s'inscrit davantage dans la configuration et le maintien d'habitats forestiers résiduels à l'échelle du paysage. Le premier chapitre de cette thèse présente la situation actuelle de la forêt boréale, de son exploitation commerciale, de même que plusieurs impacts découlant de cette exploitation sur la faune vertébrée. Y sont présentées aussi certaines notions d'écologie du paysage relatives aux processus de perte et de fragmentation de l'habitat, ainsi que les objectifs et hypothèses de la thèse. Le chapitre II résume quant à lui les connaissances relatives à différentes approches d'écologie numérique utilisées tout au long de la thèse. Le chapitre III évalue le potentiel de conservation faunique de deux types de configurations de la forêt résiduelle. L'abondance de 2 espèces de petits mammifères et de 25 espèces d'oiseaux forestiers a été estimée dans des unités mosaïques de 85-100 ha ainsi que dans des méga-blocs de 250-300 ha, de même qu'en forêt mature non perturbée (à titre de situation témoin). Aucune espèce ne présentait d'abondance inférieure à celle observée en forêt témoin, quoiqu'une faible réplication limitait la puissance statistique. Les relations faune -habitat ont été explorées à l'aide de régressions multiples entre les abondances, les variables de structure de peuplement et les caractéristiques de paysage, sur une base spécifique. Ces modèles d'utilisation d'habitat (MUHs) expliquaient une large part de la variation en abondance dont la majeure part correspondait aux effets de la structure forestière des peuplements résiduels. Les résultats suggèrent que les mosaïques et les méga-blocs sont des approches de dispersion de coupes favorables au maintien des espèces recensées, et que la planification des peuplements résiduels devrait intégrer tant la structure des peuplements résiduels que les caractéristiques du paysage.\ud Le chapitre IV s'interroge sur le potentiel faunique des parterres en régénération. Plusieurs législations forestières canadiennes permettent la récolte des structures forestières résiduelles lorsque la régénération adjacente atteint une hauteur moyenne de 3 m, sans toutefois que la capacité de tels peuplements à soutenir les espèces vertébrées des forêts originales n'ait été démontrée. Ainsi, l'abondance de 2 espèces de petits mammifères et de 19 espèces d'oiseaux a été estimée dans des parterres en régénération ainsi qu'en forêt mature continue (à titre de témoin). Les parterres en régénération permettaient de soutenir des abondances supérieures à la forêt témoin pour six des 21 espèces, et équivalentes pour 12 autres. Cependant, l'abondance de trois espèces (i.e. roitelet à couronne dorée, grimpereau brun et campagnol à dos roux de Gapper) était significativement moins élevée dans les parterres en régénération qu'en forêt témoin. Les modèles de relations faune -habitat expliquaient en moyenne 87,3 ± 1,9 % de la variabilité en abondance pour 21 espèces. La structure des peuplements expliquant encore la plus grande part de la variation en abondance. Ces résultats suggèrent que certaines espèces associées à la forêt mature pourraient montrer de fortes diminutions en abondance et voir leur maintien ultimement compromis à l'échelle du paysage suivant l'application rigoureuse de la législation en vigueur. Jusqu'à ce que les effets de la récolte des peuplements résiduels sur la faune soient mieux quantifiés, il serait favorable de maintenir de grands massifs de forêt mature tout au long de la rotation forestière. Le chapitre V modélise les effets respectifs de la perte et de la fragmentation du couvert forestier mature sur l'abondance de 11 espèces d'oiseaux. Les simulations montrent que: 1) la perte d'habitat a une influence plus marquée que la fragmentation sur l'abondance des espèces étudiées; 2) la distribution spatiale des attributs fixes de paysage (routes, lacs, cours d'eau) est le deuxième facteur ayant le plus d'effet; 3) la fragmentation influence significativement l'abondance mais n'explique qu'une faible portion de variation. Dans une perspective appliquée, les principaux résultats de cette thèse suggèrent que des efforts de conservation devraient être investis en vue de réduire l'intensité de la perte d'habitat et de maintenir davantage de forêt mature dans les paysages exploités. Puisque les espèces d'intérieur sont souvent des spécialistes de forêt mature sensibles à l'exploitation forestière, il appert que la fragmentation des habitats forestiers matures devrait également être limitée. Dans un cadre d'aménagement écosystémique en forêt boréale, diversifier la configuration des interventions devrait garantir le maintien d'un spectre plus naturel de paysages et de structure des peuplements que ce que génère actuellement l'exploitation forestière. Cette variabilité ne pourra que faciliter la conservation des populations, des espèces, des communautés et des processus écologiques. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Forêt boréale exploitée, Oiseaux forestiers, Paysages, Perte et fragmentation d'habitat, Petits mammifères, Structures forestières résiduelles

    Influence of young black spruce plantations on moose winter distribution

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    Logging in the boreal forest may benefit moose by increasing food availability. However, the influence of tree plantations on moose behavior, especially on moose spatial ecology, is poorly understood. We assessed the impacts of black spruce plantations on moose winter distribution at a landscape scale in the Bas‐Saint‐Laurent region (Québec, Canada). We used winter aerial surveys to examine relationships among plantation characteristics and other habitat variables known to affect moose distribution. The total area of plantations positively influenced moose abundance, but highly aggregated plantations resulted in fewer moose. Moose abundance was also positively associated with food availability and the density of edges between stands providing cover and stands offering high food availability, but moose abundance was negatively associated with road density. Although plantation characteristics were less influential than habitat variables related to foraging and predator avoidance, we demonstrate that the area of black spruce plantations and their configuration should be considered in moose management. We conclude that an integrated management strategy is needed to find a balance between overdeveloped road networks (needed to join homogeneously distributed plantations) and agglomerated plantations in order to mitigate impacts on moose winter distribution. © 2012 The Wildlife Society

    Behavioural strategies towards human disturbances explain individual performance in woodland caribou

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    Behavioural strategies may have important fitness, ecological and evolutionary consequences. In woodland caribou, human disturbances are associated with higher predation risk. Between 2004 and 2011, we investigated if habitat selection strategies of female caribou towards disturbances influenced their calf’s survival in managed boreal forest with varying intensities of human disturbances. Calf survival was 53 % and 43 % after 30 and 90 days following birth, respectively, and 52 % of calves that died were killed by black bear. The probability that a female lose its calf to predation was not influenced by habitat composition of her annual home range, but decreased with an increase in proportion of open lichen woodland within her calving home range. At the local scale, females that did not lose their calf displayed stronger avoidance of high road density areas than females that lost their calf to predation. Further, females that lost their calf to predation and that had a low proportion of ≤5-year-old cutovers within their calving home range were mostly observed in areas where these young cutovers were locally absent. Also, females that lost their calf to predation and that had a high proportion of ≤5-year-old cutovers within their calving home range were mostly observed in areas with a high local density of ≤5-year-old cutovers. Our study demonstrates that we have to account for human-induced disturbances at both local and regional scales in order to further enhance effective caribou management plans. We demonstrate that disturbances not only impact spatial distribution of individuals, but also their reproductive success

    Multiscale assessment of the impacts of roads and cutovers on calving site selection in woodland caribou

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    Woodland caribou (Rangifer tarandus caribou) populations are declining worldwide, and predation is considered their most important limiting factor in North America. Caribou are known to reduce predation risk by spacing themselves away from predators and alternative prey. This strategy is now compromised by forestry activities that reduce the amount of suitable caribou habitat and trigger an increase in densities of alternative prey and predators. Our objective was to investigate the influence of predation risk and food availability on selection of a calving location by woodland caribou at three different spatial scales (from coarse to fine: annual home range, calving home range, and forest stand scales) in the boreal forest of Québec, Canada. Using GPS telemetry, we identified calving locations and assessed those using Resource Selection Functions. We determined habitat characteristics using digital ecoforest and topographic maps at the annual and calving home range scales, and with vegetation surveys at the forest stand scale. Caribou selected calving locations located at relatively high elevation and where road density was low, both at the annual and calving home range scales. Within the annual home range scale, they also selected calving locations where the proportion of young and old cutovers was lower than in random areas of similar size. At the forest stand scale, females calved away from roads and young cutovers, using stands where the basal area of black spruce and balsam fir trees was low. At this fine scale, females still selected calving locations located at a relatively high elevation and where the availability of food resources was lower than in random areas located within the same habitat type. The selection of a calving location was driven by predation risk from the largest to the finest spatial scale. Therefore, our results suggest that females may not be able to lower predation risk at larger scales, despite general avoidance of roads and cutovers. We recommend amalgamating all forestry activities within intensive management zones in order to spatially isolate large patches of suitable calving habitat from anthropogenic disturbances. If not possible, we recommend concentrating forestry activities in low-lying areas since caribou consistently selected for relatively high elevations at all scales

    Climate change alone cannot explain boreal caribou range recession in Quebec since 1850

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    The contraction of species range is one of the most significant symptoms of biodiversity loss worldwide. While anthropogenic activities and habitat alteration are major threats for several species, climate change should also be considered. For species at risk, differentiating the effects of human disturbances and climate change on past and current range transformations is an important step towards improved conservation strategies. We paired historical range maps with global atmospheric reanalyses from different sources to assess the potential effects of recent climate change on the observed northward contraction of the range of boreal populations of woodland caribou (Rangifer tarandus caribou) in Quebec (Canada) since 1850. We quantified these effects by highlighting the discrepancies between different southern limits of the caribou's range (used as references) observed in the past and reconstitutions obtained through the hindcasting of the climate conditions within which caribou are currently found. Hindcasted southern limits moved ~105 km north over time under all reanalysis datasets, a trend drastically different from the ~620 km reported for observed southern limits since 1850. The differences in latitudinal shift through time between the observed and hindcasted southern limits of distribution suggest that caribou range recession should have been only 17% of what has been observed since 1850 if recent climate change had been the only disturbance driver. This relatively limited impact of climate reinforces the scientific consensus stating that caribou range recession in Quebec is mainly caused by anthropogenic drivers (i.e. logging, development of the road network, agriculture, urbanization) that have modified the structure and composition of the forest over the past 160 years, paving the way for habitat-mediated apparent competition and overharvesting. Our results also call for a reconsideration of past ranges in models aiming at projecting future distributions, especially for endangered species. -- Keywords : anthropogenic disturbances ; climate niche ; eastern Canada ; modelling ; Rangifer tarandus caribou ; species distribution model

    Conservation status of caribou in the western mountains of Canada: Protections under the species at risk act, 2002-2014

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    In April 2014, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) reviewed the status of caribou in the western mountains of Canada, in keeping with the ten-year reassessment mandate under the Species at Risk Act. Assessed as two ‘nationally significant’ populations in 2002, COSEWIC revised the conservation units for all caribou in Canada, recognising eleven extant Designatable Units (DUs), three of which -- Northern Mountain, Central Mountain, and Southern Mountain -- are found only in western Canada. The 2014 assessment concluded that the condition of many subpopulations in all three DUs had deteriorated. As a result of small and declining population sizes, the Central Mountain and Southern Mountain DUs are now recognised as endangered. Recent declines in a number of Northern Mountain DU subpopulations did not meet thresholds for endangered or threatened, and were assessed as of special concern. Since the passage of the federal Species at Risk Act in 2002, considerable areas of habitat were managed or conserved for caribou, although disturbance from cumulative human development activities has increased during the same period. Government agencies and local First Nations are attempting to arrest the steep decline of some subpopulations by using predator control, maternal penning, population augmentation, and captive breeding. Based on declines, future developments and current recovery effects, we offer the following recommendations: 1) where recovery actions are necessary, commit to simultaneously reducing human intrusion into caribou ranges, restoring habitat over the long term, and conducting short-term predator control, 2) carefully consider COSEWIC’s new DU structure for management and recovery actions, especially regarding translocations, 3) carry out regular surveys to monitor the condition of Northern Mountain caribou subpopulations and immediately implement preventative measures where necessary, and 4) undertake a proactive, planned approach coordinated across jurisdictions to conserve landscape processes important to caribou conservation

    Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

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    A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

    Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan

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    This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good
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