Time-like flows of energy-momentum and particle trajectories for the Klein-Gordon equation

The Klein-Gordon equation is interpreted in the de Broglie-Bohm manner as a single-particle relativistic quantum mechanical equation that defines unique time-like particle trajectories. The particle trajectories are determined by the conserved flow of the intrinsic energy density which can be derived from the specification of the Klein-Gordon energy-momentum tensor in an Einstein-Riemann space. The approach is illustrated by application to the simple single-particle phenomena associated with square potentials.Comment: 14 pages, 11 figure

Reduced breeding success in great black-backed gulls (Larus marinus) due to harness-mounted GPS device

Animal-borne bio-logging devices are routinely fitted to seabirds to learn about their behaviour and physiology, as well as their interactions with the marine environment. The assessment and reporting of deleterious impacts from such devices on the individuals carrying them is critical to inform future work and improve data quality and animal welfare. We assessed the impacts of thoracic-harness attachments on the breeding performance and inter-annual return rates of Great Black-backed Gulls. We found that tagged individuals hatched fewer eggs per nest (0.67) than two different control groups (handled but not tagged – 2.0, and not handled – 1.9) and had lower hatching success rates per nest (27% compared with 81% and 82% in control groups). Inter-annual return rates were similar between tagged and control groups, but the harness attachment potentially caused the death of an individual 5 days after deployment. Overall, the harness attachment was a lead driver of nest failure. We urge extreme caution for those wanting to use harness-mounted devices on Great Black-backed Gulls

Partial niche partitioning in three sympatric gull species through foraging areas and habitat selection

Anthropogenic habitat change is having a detrimental impact on biodiversity worldwide, altering the foraging behaviour and population dynamics of many species. Generalist species often adapt by broadening their resource use and/or exploiting human‐modified environments. However, habitat changes that reduce the availability of good quality resources can lead to increased interspecific competition among sympatric species and increased conflict with human activities. We investigated the breeding season foraging ecology of three sympatric gull species, Lesser Black‐backed (Larus fuscus), Herring (Larus argentatus) and Great Black‐backed Gulls (Larus marinus), from the same colony in Scotland. Using GPS tracking data, we analysed foraging ranges, spatial distributions and habitat preferences to determine the extent of the gulls' niche partitioning and use of human‐modified landscapes. Our findings revealed considerable overlap in resource use between species. However, species‐level differences in spatial distributions and habitat selection demonstrated partial niche partitioning. Lesser Black‐backed Gulls had significantly larger foraging ranges than Herring and Great Black‐backed Gulls, indicating spatial segregation. Herring and Great Black‐backed Gulls strongly selected for landfill and coastal habitats. Lesser Black‐backed Gulls also selected for these habitats but primarily used agricultural areas. Individual‐level analysis revealed that most species‐level selection for urban, landfill and harbour habitats was driven by a subset of individuals. The observed limited niche partitioning indicates that further habitat loss or degradation could negatively impact all three gull species unless the extent of niche partitioning changes. Given that most habitats used were linked to human activities, further anthropogenic change may displace gulls from preferred foraging areas, increasing competition for limited resources and exacerbating conflicts with human activities in alternative habitats. By simultaneously tracking sympatric species, we can better understand how shifts in resource availability may impact interspecific competition and interactions with human activities to help inform management actions and mitigate conflict with humans, particularly around licensed control

Hotspots in the grid: Avian sensitivity and vulnerability to collision risk from energy infrastructure interactions in Europe and North Africa

Wind turbines and power lines can cause bird mortality due to collision or electrocution. The biodiversity impacts of energy infrastructure (EI) can be minimised through effective landscape-scale planning and mitigation. The identification of high-vulnerability areas is urgently needed to assess potential cumulative impacts of EI while supporting the transition to zero carbon energy. We collected GPS location data from 1,454 birds from 27 species susceptible to collision within Europe and North Africa and identified areas where tracked birds are most at risk of colliding with existing EI. Sensitivity to EI development was estimated for wind turbines and power lines by calculating the proportion of GPS flight locations at heights where birds were at risk of collision and accounting for species' specific susceptibility to collision. We mapped the maximum collision sensitivity value obtained across all species, in each 5 × 5 km grid cell, across Europe and North Africa. Vulnerability to collision was obtained by overlaying the sensitivity surfaces with density of wind turbines and transmission power lines. Results: Exposure to risk varied across the 27 species, with some species flying consistently at heights where they risk collision. For areas with sufficient tracking data within Europe and North Africa, 13.6% of the area was classified as high sensitivity to wind turbines and 9.4% was classified as high sensitivity to transmission power lines. Sensitive areas were concentrated within important migratory corridors and along coastlines. Hotspots of vulnerability to collision with wind turbines and transmission power lines (2018 data) were scattered across the study region with highest concentrations occurring in central Europe, near the strait of Gibraltar and the Bosporus in Turkey. Synthesis and applications. We identify the areas of Europe and North Africa that are most sensitive for the specific populations of birds for which sufficient GPS tracking data at high spatial resolution were available. We also map vulnerability hotspots where mitigation at existing EI should be prioritised to reduce collision risks. As tracking data availability improves our method could be applied to more species and areas to help reduce bird-EI conflicts