Patterns and correlates of claims for brown bear damage on a continental scale

Wildlife damage to human property threatens human-wildlife coexistence. Conflicts arising from wildlife damage in intensively managed landscapes often undermine conservation efforts, making damage mitigation and compensation of special concern for wildlife conservation. However, the mechanisms underlying the occurrence of damage and claims at large scales are still poorly understood. Here, we investigated the patterns of damage caused by brown bears Ursus arctos and its ecological and socio-economic correlates at a continental scale. We compiled information about compensation schemes across 26 countries in Europe in 2005-2012 and analysed the variation in the number of compensated claims in relation to (i) bear abundance, (ii) forest availability, (iii) human land use, (iv) management practices and (v) indicators of economic wealth. Most European countries have a posteriori compensation schemes based on damage verification, which, in many cases, have operated for more than 30 years. On average, over 3200 claims of bear damage were compensated annually in Europe. The majority of claims were for damage to livestock (59%), distributed throughout the bear range, followed by damage to apiaries (21%) and agriculture (17%), mainly in Mediterranean and eastern European countries. The mean number of compensated claims per bear and year ranged from 0·1 in Estonia to 8·5 in Norway. This variation was not only due to the differences in compensation schemes; damage claims were less numerous in areas with supplementary feeding and with a high proportion of agricultural land. However, observed variation in compensated damage was not related to bear abundance. Synthesis and applications. Compensation schemes, management practices and human land use influence the number of claims for brown bear damage, while bear abundance does not. Policies that ignore this complexity and focus on a single factor, such as bear population size, may not be effective in reducing claims. To be effective, policies should be based on integrative schemes that prioritize damage prevention and make it a condition of payment of compensation that preventive measures are applied. Such integrative schemes should focus mitigation efforts in areas or populations where damage claims are more likely to occur. Similar studies using different species and continents might further improve our understanding of conflicts arising from wildlife damage

Search for a muon EDM at the Paul Scherrer Institute

Electric dipole moments (EDM) of non-degenerate systems with angular momentum violate parity and time symmetry, and by the virtue of the CPT-theorem also the combined symmetry of charge and parity (CP). Although CP violation (CPV) is an established ingredient of the weak sector of the standard model of particle physics (SM), its contribution to an EDM of a fundamental particle is too small to be measured any time soon. Therefore, any discovery of an EDM would be a genuine signal of yet unobserved physics. As the muon is the only accessible probe of the second generation of fermions and the only fermion of which the EDM can be measured on the bare particle, a search for a muon EDM thus uniquely complements more established searches using atoms and neutrons. Here we report on the status of a search for the muon EDM using the frozen-spin technique in a compact storage ring, aiming for an improvement by three orders of magnitude in sensitivity compared to the current best direct limit dμ ≤ 1.8 × 10-19 e·cm

Anomalous spin precession systematic effects in the search for a muon EDM using the frozen-spin technique

At the Paul Scherrer Institut (PSI), we are currently working on the development of a high-precision apparatus with the aim of searching for the muon electric dipole moment (EDM) with unprecedented sensitivity. The underpinning principle of this experiment is the frozen-spin technique, a method that suppresses the spin precession due to the anomalous magnetic moment, thereby enhancing the signal-to-noise ratio for EDM signals. This increased sensitivity facilitates measurements that would be difficult to achieve with conventional $g - 2$ muon storage rings. Given the availability of the $p = 125$ MeV/$c$ muon beam at PSI, the anticipated statistical sensitivity for the EDM after a year of data collection is $6\times 10^{-23}e\cdot$cm. To achieve this goal, it is imperative to meticulously analyse and mitigate any potential spurious effects that could mimic EDM signals. In this study, we present a quantitative methodology to evaluate the systematic effects that might arise in the context of employing the frozen-spin technique within a compact storage ring. Our approach entails the analytical derivation of equations governing the motion of the muon spin in the electromagnetic (EM) fields intrinsic to the experimental setup, validated through subsequent numerical simulations. We also illustrate a method to calculate the cumulative geometric (Berry's) phase. This work complements ongoing experimental efforts to detect a muon EDM at PSI and contributes to a broader understanding of spin-precession systematic effects.Comment: submitted to The European Physical Journal

Status of the search for a muon EDM using the frozen-spin technique

Despite the many successes of the Standard Model of particle physics, there are still several physical observations that it cannot explain, such as the matter-antimatter asymmetry, non-zero neutrino masses, and the microscopic nature of dark matter. To address these limitations, extensions to the standard model are necessary, and searches for electric dipole moments (EDMs) of leptons are valuable test. The search for a muon EDM is the only search on a bare lepton of the second generation, complementing the searches for an EDM of the electron using polar molecules. A non-zero EDM of the muon would indicate Charge-Parity symmetry violation beyond the standard model. A dedicated experimental search for the muon EDM is being set up at PSI using the frozen-spin technique. In this technique, the anomalous spin precession of the muons in a storage ring is suppressed by applying an electric field in the radial direction. The muon EDM experiment will take place in two phases: the first phase will demonstrate the frozen-spin technique using a precursor experiment with 28 MeV/c muons, while the second phase will make use of 125 MeV/c muons, which could search for the muon EDM with a sensitivity of 6 × 10-23 e·cm. In this talk, we describe the precursor experiment at PSI and provide an update on the status of the experiment

A compact frozen-spin trap for the search for the electric dipole moment of the muon

The electric dipole moments~(EDM) of fundamental particles inherently violate parity~(P) and time-reversal~(T) symmetries. By virtue of the CPT theorem in quantum field theory, the latter also implies the violation of the combined charge-conjugation and parity~(CP) symmetry. We aim to measure the EDM of the muon using the frozen-spin technique within a compact storage trap. This method exploits the high effective electric field, \$E \approx 165\$ MV/m, experienced in the rest frame of the muon with a momentum of about 23 MeV/c when it passes through a solenoidal magnetic field of \$|\vec{B}|=2.5\$ T. In this paper, we outline the fundamental considerations for a muon EDM search and present a conceptual design for a demonstration experiment to be conducted at secondary muon beamlines of the Paul Scherrer Institute in Switzerland. In Phase~I, with an anticipated data acquisition period of 200 days, the expected sensitivity to a muon EDM is 4E-21 ecm. In a subsequent phase, Phase~II, we propose to improve the sensitivity to 6E-23 ecm using a dedicated instrument installed on a different beamline that produces muons of momentum 125 MeV/c}

Trophic Interactions Are Key to Understanding the Effects of Global Change on the Distribution and Functional Role of the Brown Bear

Biotic interactions are expected to influence species' responses to global changes, but they are rarely considered across broad spatial extents. Abiotic factors are thought to operate at larger spatial scales, while biotic factors, such as species interactions, are considered more important at local scales within communities, in part because of the knowledge gap on species interactions at large spatial scales (i.e., the Eltonian shortfall). We assessed, at a continental scale, (i) the importance of biotic interactions, through food webs, on species distributions, and (ii) how biotic interactions under scenarios of climate and land-use change may affect the distribution of the brown bear (Ursus arctos). We built a highly detailed, spatially dynamic, and empirically sampled food web based on the energy contribution of 276 brown bear food species from different taxa (plants, vertebrates, and invertebrates) and their ensemble habitat models at high resolution across Europe. Then, combining energy contribution and predicted habitat of food species, we modelled energy contribution across space and included these layers within Bayesian-based models of the brown bear distribution in Europe. The inclusion of biotic interactions considerably improved our understanding of brown bear distribution at large (continental) scales compared with Bayesian models including only abiotic factors (climate and land use). Predicted future range shifts, which included changes in the distribution of food species, varied greatly when considering various scenarios of change in biotic factors, providing a warning that future indirect climate and land-use change are likely to have strong but highly uncertain impacts on species biogeography. Our study confirmed that advancing our understanding of ecological networks of species interactions will improve future projections of biodiversity change, especially for modelling species distributions and their functional role under climate and land-use change scenarios, which is key for effective conservation of biodiversity and ecosystem services

Brown bear attacks on humans : a worldwide perspective

The increasing trend of large carnivore attacks on humans not only raises human safety concerns but may also undermine large carnivore conservation efforts. Although rare, attacks by brown bears Ursus arctos are also on the rise and, although several studies have addressed this issue at local scales, information is lacking on a worldwide scale. Here, we investigated brown bear attacks (n = 664) on humans between 2000 and 2015 across most of the range inhabited by the species: North America (n = 183), Europe (n = 291), and East (n = 190). When the attacks occurred, half of the people were engaged in leisure activities and the main scenario was an encounter with a female with cubs. Attacks have increased significantly over time and were more frequent at high bear and low human population densities. There was no significant difference in the number of attacks between continents or between countries with different hunting practices. Understanding global patterns of bear attacks can help reduce dangerous encounters and, consequently, is crucial for informing wildlife managers and the public about appropriate measures to reduce this kind of conflicts in bear country.Peer reviewe

Trophic interactions are key to understanding the effects of global change on the distribution and functional role of the brown bear

Biotic interactions are expected to influence species' responses to global changes, but they are rarely considered across broad spatial extents. Abiotic factors are thought to operate at larger spatial scales, while biotic factors, such as species interactions, are considered more important at local scales within communities, in part because of the knowledge gap on species interactions at large spatial scales (i.e., the Eltonian shortfall). We assessed, at a continental scale, (i) the importance of biotic interactions, through food webs, on species distributions, and (ii) how biotic interactions under scenarios of climate and land-use change may affect the distribution of the brown bear (Ursus arctos). We built a highly detailed, spatially dynamic, and empirically sampled food web based on the energy contribution of 276 brown bear food species from different taxa (plants, vertebrates, and invertebrates) and their ensemble habitat models at high resolution across Europe. Then, combining energy contribution and predicted habitat of food species, we modelled energy contribution across space and included these layers within Bayesian-based models of the brown bear distribution in Europe. The inclusion of biotic interactions considerably improved our understanding of brown bear distribution at large (continental) scales compared with Bayesian models including only abiotic factors (climate and land use). Predicted future range shifts, which included changes in the distribution of food species, varied greatly when considering various scenarios of change in biotic factors, providing a warning that future indirect climate and land-use change are likely to have strong but highly uncertain impacts on species biogeography. Our study confirmed that advancing our understanding of ecological networks of species interactions will improve future projections of biodiversity change, especially for modelling species distributions and their functional role under climate and land-use change scenarios, which is key for effective conservation of biodiversity and ecosystem service