418 research outputs found

    The ecology of reintroduced lions on the Welgevonden Private Game Reserve, Waterberg

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    Five lions were reintroduced to the Welgevonden Private Game Reserve in 1998. These lions were studied to increase the limited knowledge of the ecology of reintroduced lions on small wildlife reserves, and to provide baseline data to the reserve management from which to develop management decisions. In the past, reintroduction attempts of felids have often failed because the animals failed to establish ranges in the new environment. During the current study, homing behaviour and range establishment of the reintroduced lions were studied and used as an indication of the success of the reintroduction attempt. The ease with which lions on Welgevonden established ranges indicated that they did not experience problems with adapting to their new environment The population dynamics of the reintroduced lion population were investigated. The population grew rapidly due to early breeding and short inter-litter intervals. The collected data were used to model the lion population using VORTEX population modelling software. Various potential management strategies to reduce the population growth were also modelled and discussed. The feeding ecology and predation patterns of the reintroduced lions• were investigated to give an indication of the predator-prey relationships on Welgevonden. These data were used in a model that investigated the effect of lion predation on the various prey populations of Welgevonden. The model was also used to test the influence of other factors on the prey populations, as well as the number of killing lions that can be supported by the prey population. The study has shown that reintroduction can be used successfully to establish a lion population on a small game reserve, but that certain management actions will increase the chances of success. However, continual monitoring and management will be necessary to ensure the long-term viability of the lion and prey populations. <p.Dissertation (MSc (Wildlife Management))--University of Pretoria, 2006.Centre for Wildlife Managementunrestricte

    Foraging and habitat specialization by female leopards (Panthera pardus) in the Waterberg Mountains of South Africa

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    Carnivores that persist outside of protected areas are often deemed to have highly adaptable and generalist foraging strategies. Using data from three GPS-collared female leopards (Panthera pardus) and over an eight-month period, we attempted to establish whether leopards in a mountainous landscape display preferential behaviour (i.e. specialist) or not (i.e. generalist).We investigated whether female leopards used habitats in accordance with availability for both hunting and regular activities, and whether female leopards demonstrated preference for a particular prey species. Finally, we assessed tree caching behaviour and discuss leopard spatial dynamics in the context of superior competitors, such as lions (Panthera leo). Female leopards demonstrated selection for certain prey species. Mixed closed woodland (greatest vegetation density; lowest prey density) and tall open woodland (greatest vegetation biomass; high prey density) were preferred over other habitats. Female leopards on Welgevonden cached significantly larger prey species in trees. Our results suggest that female leopards in this landscape are selecting habitats – enabling the exploitation of certain ecological features – that balance energy expenditure against the likelihood of capturing prey in an attempt to maximize efficiency, whilst reducing inter-specific competition.We suggest that female leopards are limited in their foraging ability as a result of interference competition by superior species like lions, which in turn, affects their choice of prey. These findings highlight the potential importance of numerous ecological, spatio-temporal, and anthropogenic factors that influence leopard behaviour, and therefore have significant implications for leopard persistence and conservation.The Wilson Foundation and the Centre for Wildlife Management. L.H.S. was supported by a NRF grant (No. 74819).http://www.sawma.co.za/am201

    Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

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    Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

    Religiosit\ue0 e civilt\ue0. Conoscenze, confronti, influssi reciproci tra le religioni (secoli X-XIV)

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    Si riflette su come i cristiani medievali abbiano percorso itinerari che, a partire dalla coscienza del loro essere profondo, li hanno portati a misurarsi con i messaggi sacri ed etici delle altre religioni, utilizzando sia le osservazioni empiriche, sia lo studio approfondito delle altrui tradizioni culturali, sia la traduzione e la riflessione sui testi sacri delle altre fedi religiose, con particolare riferimento al Corano

    Multiplicity dependence of light (anti-)nuclei production in p–Pb collisions at sNN=5.02 TeV

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    The measurement of the deuteron and anti-deuteron production in the rapidity range −1 < y < 0 as a function of transverse momentum and event multiplicity in p–Pb collisions at √sNN = 5.02 TeV is presented. (Anti-)deuterons are identified via their specific energy loss dE/dx and via their time-of- flight. Their production in p–Pb collisions is compared to pp and Pb–Pb collisions and is discussed within the context of thermal and coalescence models. The ratio of integrated yields of deuterons to protons (d/p) shows a significant increase as a function of the charged-particle multiplicity of the event starting from values similar to those observed in pp collisions at low multiplicities and approaching those observed in Pb–Pb collisions at high multiplicities. The mean transverse particle momenta are extracted from the deuteron spectra and the values are similar to those obtained for p and particles. Thus, deuteron spectra do not follow mass ordering. This behaviour is in contrast to the trend observed for non-composite particles in p–Pb collisions. In addition, the production of the rare 3He and 3He nuclei has been studied. The spectrum corresponding to all non-single diffractive p-Pb collisions is obtained in the rapidity window −1 < y < 0 and the pT-integrated yield dN/dy is extracted. It is found that the yields of protons, deuterons, and 3He, normalised by the spin degeneracy factor, follow an exponential decrease with mass number

    W and Z boson production in p-Pb collisions at sNN\sqrt{s_{\rm NN}} = 5.02 TeV

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    The W and Z boson production was measured via the muonic decay channel in proton-lead collisions at sNN=5.02 \sqrt{s_{\mathrm{NN}}}=5.02 TeV at the Large Hadron Collider with the ALICE detector. The measurement covers backward (−4.46 10 GeV/c are determined. The results are compared to theoretical calculations both with and without including the nuclear modification of the parton distribution functions. The W-boson production is also studied as a function of the collision centrality: the cross section of muons from W-boson decays is found to scale with the average number of binary nucleon-nucleon collisions within uncertainties

    Measurement of the production of high-pTp_{\rm T} electrons from heavy-flavour hadron decays in Pb-Pb collisions at sNN\mathbf{\sqrt{\it s_{\rm{NN}}}} = 2.76 TeV

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    Electrons from heavy-flavour hadron decays (charm and beauty) were measured with the ALICE detector in Pb–Pb collisions at a centre-of-mass of energy sNN=2.76 TeV . The transverse momentum ( pT ) differential production yields at mid-rapidity were used to calculate the nuclear modification factor RAA in the interval 3<pT<18 GeV/ c . The RAA shows a strong suppression compared to binary scaling of pp collisions at the same energy (up to a factor of 4) in the 10% most central Pb–Pb collisions. There is a centrality trend of suppression, and a weaker suppression (down to a factor of 2) in semi-peripheral (50–80%) collisions is observed. The suppression of electrons in this broad pT interval indicates that both charm and beauty quarks lose energy when they traverse the hot medium formed in Pb–Pb collisions at LHC

    Centrality dependence of the pseudorapidity density distribution for charged particles in Pb-Pb collisions at sNN=5.02\sqrt{s_{\rm NN}}=5.02 TeV

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    We present the charged-particle pseudorapidity density in Pb–Pb collisions at sNN=5.02 TeV in centrality classes measured by ALICE. The measurement covers a wide pseudorapidity range from −3.5 to 5, which is sufficient for reliable estimates of the total number of charged particles produced in the collisions. For the most central (0–5%) collisions we find 21400±1300 , while for the most peripheral (80–90%) we find 230±38 . This corresponds to an increase of (27±4)% over the results at sNN=2.76 TeV previously reported by ALICE. The energy dependence of the total number of charged particles produced in heavy-ion collisions is found to obey a modified power-law like behaviour. The charged-particle pseudorapidity density of the most central collisions is compared to model calculations — none of which fully describes the measured distribution. We also present an estimate of the rapidity density of charged particles. The width of that distribution is found to exhibit a remarkable proportionality to the beam rapidity, independent of the collision energy from the top SPS to LHC energies
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