Bridge Movement Research Articles

Machine Learning Clustering Techniques to Support Structural Monitoring of the Valgadena Bridge Viaduct (Italy)

The lack of precise and comprehensive information about the health of bridges, and in particular long span ones, can lead to incorrect decisions regarding maintenance, repair, modernization, and reinforcement of the structure itself. While the consequences of inadequate interventions are quite apparent, incorrect decisions can also result in unnecessary or misdirected actions. For example, an inadequate assessment of the structural health can lead to the modernization and replacement of some components that are still sound. Structural Health Monitoring (SHM) involves the use of time series derived from periodic measurements of the structure’s behavior, considered in its operational and load environment. The goal is to determine its response to various solicitations and, in particular, to highlight any critical issue in the structure’s behavior that may affect its reliability and safety due to anomalies and deterioration. This paper proposes an SHM method applied to the Valgadena bridge, one of the tallest viaducts in Italy and Europe (maximum height 160 m), located on the Altopiano dei Sette Comuni in the Province of Vicenza. Despite the fact that the viaduct itself had already been monitored during its construction using classical geometric leveling techniques, the methodology proposed here is based instead on the use of affordable dual-frequency GNSS (Global Navigation Satellite System) receivers to determine static and dynamic components of the bridge movements. Specifically, an effective combination of time series analysis methods and machine learning techniques is proposed in order to determine the vibration modes of the monitored viaduct. Monitoring is performed in regular operation conditions of the bridge (operational modal analysis (OMA)), and the use of certain machine learning methods aims at supporting the development of an effective automatic OMA procedure. To be more specific, the random decrements technique is used in order to make the vibration characteristics of the collected signals more apparent. Time-domain-based subspace identification is applied in order to determine a proper model of the collected measurements. Then, clustering methods, namely DBSCAN (Density-Based Spatial Clustering of Applications with Noise) and GMMs (Gaussian Mixture Models), are used in order to reliably estimate the system poles, and hence the corresponding vibration characteristics. The performance of the considered methods is compared on the Valgadena bridge case study, showing that the use of GMM clustering reduces, with respect to DBSCAN, the impact of the choice of certain parameter values in the considered case.

Modeling regional occupancy of fishes using acoustic telemetry: a model comparison framework applied to lake trout

Acoustic telemetry is a common tool used in fisheries management to estimate fish space use (i.e., occupancy) from a local habitat scale to entire systems. Numerous analytical models have been developed to estimate different aspects of fish movement from telemetry datasets, yet evaluations of model performance and comparisons among models are limited. Here, we develop a framework to evaluate model estimates of regional occupancy in large and fragmented systems using an acoustic receiver array in Lake Champlain. We simulated the tracks of 100 acoustically tagged fish using a random walk function and created detection events based on receiver positions and distance-based detection probability. Regional occupancy for the simulated data was estimated by six movement models that ranged in analytical complexity, and results were compared to the true distributions for each simulated track to evaluate model error. The six movement models included: (1) a basic residency index using detections alone; (2) a residency index using last-observation-carried-forward; (3) a centers of activity model; (4) linear and non-linear interpolations (i.e., least-cost paths); and (5 and 6) two dynamic Brownian bridge movement models generated using separate packages in R. We developed a model selection process to compare model performance and select the optimal analysis based on simulation error. This process showed significant differences in model performance among the six movement models based on model error. Overall, the model generating least-cost paths using linear and non-linear interpolations consistently provided the most accurate regional occupancy estimates. Based on these simulation results, we applied this model to a case study that evaluated patterns in the regional distribution of stocked lake trout (Salvelinus namaycush) in Lake Champlain, which demonstrated distinct regional occupancy of two stocked lake trout groups. These results demonstrate potential for large variability in interpretation of acoustic telemetry data for describing regional fish distribution dependent on the analytical method used.

Estimating ungulate migration corridors from sparse movement data

AbstractMany ungulates migrate between distinct summer and winter ranges, and identifying, mapping, and conserving these migration corridors have become a focus of local, regional, and global conservation efforts. Brownian bridge movement models (BBMMs) are commonly used to empirically identify these seasonal migration corridors; however, they require location data sampled at relatively frequent intervals to obtain a robust estimate of an animal's movement path. Fitting BBMMs to sparse location data violates the assumption of conditional random movement between successive locations, overestimating the area (and width) of a migration corridor when creating individual and population‐level occurrence distributions and precluding the use of low‐frequency, or sparse, data in mapping migration corridors. In an effort to expand the utility of BBMMs to include sparse GPS data, we propose an alternative approach to model migration corridors from sparse GPS data. We demonstrate this method using GPS data collected every 2 h from four mule deer (Odocoileus hemionus) and four elk (Cervus canadensis) herds within Wyoming and Idaho. First, we used BBMMs to estimate a baseline corridor for the 2‐h data. We then subsampled the 2‐h data to one location every 12 h (a proxy for sparse data) and fitted BBMMs to the 12‐h data using a fixed motion variance (FMV) value, instead of estimating the Brownian motion variance empirically. A range of FMV values was tested to identify the value that best approximated the baseline migration corridor. FMV values within a species‐specific range (mule deer: 400–1200 m2; elk: 600–1600 m2) successfully delineated migration corridors similar to the 2‐h baseline corridors; overall, lower values delineated narrower corridors and higher values delineated wider corridors. Optimal FMV values of 800 m2 (mule deer) and 1000 m2 (elk) decreased the inflation of the 12‐h corridors relative to the 2‐h corridors from traditional BBMMs. This FMV approach thus enables using sparse movement data to approximate realistic migration corridor dimensions, providing an important alternative when movement data are collected infrequently. This approach greatly expands the number of datasets that can be used for migration corridor mapping—a useful tool for management and conservation across the globe.

3D Bionic Water Harvesting System for Efficient Fog Capturing and Transporting

AbstractFog harvest has emerged as a direct and efficient water harvesting technology to relieve the intense pressure of freshwater scarcity worldwide. With the vagaries of climate and increasing amount of energy consumption, high‐efficiency fog harvest devices focus on the fast water droplet capture and transportation are highly desired. In this study, a novel harp structure is developed using cross‐twisted copper filaments arranged in a spatial triangular pattern to enhance water droplet capture and transportation. Inspired by the natural differences in Laplace pressure observed in cactus and spider silks, this design accelerates the movement of water bridges. Besides, drawing on the fruit waxes on the surface of hogweed and blueberries, a paraffin wax coating is applied on the copper sheet frame to create a solid slip frame, improving the synergy between filament capture and frame transportation. The monolithic fog collector (MFC) thus achieves a significant increase in fog harvest efficiency and demonstrates excellent durability. Integration of the MFCs into a 3D high‐efficiency fog harvest system results in a harvest rate of 0.5027 g cm−2 min−1, showing promise for practical applications due to its durability, simplicity, and environmental friendliness.

Female black bear home range and resource selection in relation to West Virginia mine lands

AbstractWildlife space use is a key component to consider when determining effective conservation and management practices. Home range size and resource selection can vary temporally and spatially depending on mortality risks in the area and access to food resources. Lands used for coal mining can contain unique mortality risks and food resources for American black bears (Ursus americanus) relative to surrounding landscapes due to hunting restrictions, vegetation planted as part of the reclamation process, and other anthropogenic food resources. We examined the influence of mining sites on resource selection of female black bears in southern West Virginia, USA, during 2007 and 2008. We estimated home range size with Brownian Bridge movement models and evaluated variation in home range size with mixed‐effects linear regression. We evaluated resource selection with mixed‐effects Poisson point process models. On mine sites, the mean 95% home range for female black bears was 1,996 ha (SD = 2,633) in the autumn and 544 ha (SD = 238) in the spring, and on non‐mine sites the mean 95% home range was 1,926 ha (SD = 1,292) in the autumn and 771 ha (SD = 480) in the spring. Our resource selection model indicated black bears used nonhunting zones associated with mine lands much greater than their availability, and that black bears in mine areas disproportionately used areas in close proximity to anthropogenic structures. Interannual variation in home range size was likely associated with mast conditions, because smaller home ranges were associated with high mast production. Our data suggest black bears may be using non‐hunting zones within mine lands as refugia from hunting and are using anthropogenic food sources available at refuse sites on mine lands, which may increase regional black bear populations in areas with high mining activity.

Spatial overlap of gray wolves and ungulate prey changes seasonally corresponding to prey migration

BackgroundPrey are more vulnerable during migration due to decreased familiarity with their surroundings and spatially concentrated movements. Predators may respond to increased prey vulnerability by shifting their ranges to match prey. Moose (Alces alces) and white-tailed deer (Odocoileus virginianus) are primary gray wolf (Canis lupus) prey and important subsistence species for Indigenous communities. We hypothesized wolves would increase use of ungulate migration corridors during migrations and predicted wolf distributions would overlap primary available prey.MethodsWe examined seasonal gray wolf, moose, and white-tailed deer movements on and near the Grand Portage Indian Reservation, Minnesota, USA. We analyzed GPS collar data during 2012–2021 using Brownian bridge movement models (BBMM) in Migration Mapper and mechanistic range shift analysis (MRSA) to estimate individual- and population-level occurrence distributions and determine the status and timing of range shifts. We estimated proportional overlap of wolf distributions with moose and deer distributions and tested for differences among seasons, prey populations, and wolf sex and pack affiliations.ResultsWe identified a single migration corridor through which white-tailed deer synchronously departed in April and returned in October–November. Gray wolf distributions overlapped the deer migration corridor similarly year-round, but wolves altered within-range distributions seasonally corresponding to prey distributions. Seasonal wolf distributions had the greatest overlap with deer during fall migration (10 October–28 November) and greatest overlap with moose during summer (3 May–9 October).ConclusionsGray wolves did not increase their use of the white-tailed deer migration corridor but altered distributions within their territories in response to seasonal prey distributions. Greater overlap of wolves and white-tailed deer in fall may be due to greater predation success facilitated by asynchronous deer migration movements. Greater summer overlap between wolves and moose may be linked to moose calf vulnerability, American beaver (Castor canadensis) co-occurrence, and reduced deer abundance associated with migration. Our results suggest increases in predation pressure on deer in fall and moose in summer, which can inform Indigenous conservation efforts. We observed seasonal plasticity of wolf distributions suggestive of prey switching; that wolves did not exhibit migratory coupling was likely due to spatial constraints resulting from territoriality.

Female Deer Movements Relative to Firearms Hunting in Northern Georgia, USA.

Perceived risk associated with hunters can cause white-tailed deer (Odocoileus virginianus) to shift their activity away from key foraging areas or alter normal movements, which are important considerations in managing hunting and its effects on a population. We studied the effects of seven firearms hunts on the movements of 20 female deer in two Wildlife Management Areas within the Chattahoochee National Forest of northern Georgia, USA, during the 2018-2019 and 2019-2020 hunting seasons. Deer populations and the number of hunters in our study area have declined significantly since the 1980s. In response, hunting regulations for the 2019-2020 hunting season eliminated opportunities for harvesting female deer. To evaluate the indirect effects of antlered deer hunting on non-target female deer, we calculated 90% utilization distributions (UDs), 50% UDs, and step lengths for pre-hunt, hunt, and post-hunt periods using the dynamic Brownian bridge movement model. Data included 30 min GPS locations for 44 deer-hunt combinations. Pre-hunt 50% UDs (x- = 7.0 ha, SE = 0.4 ha) were slightly greater than both hunt (x- = 6.0 ha, SE = 0.3 ha) and post-hunt (x- = 6.0 ha, SE = 0.2 ha) 50% UDs (F = 3.84, p = 0.03). We did not detect differences in step length, nor did we detect differences in size or composition of 90% UDs, among the periods. Overall, our results suggest that the low level of hunting pressure in our study area and lack of exposure to hunters led to no biologically significant changes in female deer movements. To the extent of the findings presented in this paper, adjustments to the management of hunting in our study area do not appear to be necessary to minimize hunting-related disturbances for female deer. However, managers should continue to consider female deer behavior when evaluating future changes to hunting regulations.

GPS Tracking Reveals the White-Tailed Eagle Haliaeetus albicilla as an Ambassador for the Natura 2000 Network

The Natura 2000 network of protected areas is the backbone of species conservation in the European Union. We investigated whether Austrian-hatched white-tailed eagles (Haliaeetus albicilla) make particular use of this multinational network during their natal dispersal, and what habitats were of importance to the eagles. We analyzed the utilization distribution of 907,466 GPS locations from 38 dispersing white-tailed eagles using a dynamic Brownian Bridge Movement Model. Eagles ranged over a huge area of central-eastern Europe. Natura 2000 sites overlapped with 67% of the resulting 50% isopleth; i.e., a high probability of utilization of Natura 2000 areas by white-tailed eagles was found. White-tailed eagles used wetlands, waterbodies, and deciduous forests adjacent to wet habitats disproportionately often. Coniferous forests and settlements were avoided. Anthropogenically caused mortalities hardly occurred within Natura 2000 sites. Our study suggests that the Natura 2000 network is a crucial tool for conserving the white-tailed eagle. This top predator is an ambassador for the Natura 2000 idea during all life stages, and should continue to be a conservation priority of the network.

Survival and behavior of Mojave desert tortoises head‐started with and without outdoor rearing

AbstractMojave desert tortoise (Gopherus agassizii) populations in some regions have declined by >50% since 2004, prompting the need for more research on ways to recover populations. One possible recovery tool is head‐starting (i.e., the act of protecting and raising juvenile tortoises to sizes that increase survival upon release); however, head‐starting can have high start‐up and maintenance costs that can limit its feasibility. Strategies that reduce cost and rearing duration may foster broader and more effective use. We released and radio‐tracked 60 juvenile tortoises in the Mojave National Preserve in California, USA, that had been reared under 2 treatments: those reared 1 year indoors after hatching, then 1 year outdoors (combo) and those reared just 1 year indoors (indoor‐only). We tested whether indoor‐only rearing alone could be a more efficient means of producing robust head‐started tortoises. We examined the behavior, movement, and survival of tortoises after release into the wild from 2020 to 2021 to determine whether these outcomes differed between husbandry treatments. Combo tortoises tended to perform settling behaviors (mean ± 1 SE days to building first burrow = 6.7 ± 0.8, entering dormancy = 23.3 ± 2.1, and emerging from dormancy = 189.6 ± 4.4) earlier than indoor‐only tortoises (7.4 ± 0.9, 31.5 ± 2.6, and 193.9 ± 5.9, respectively), but this difference was not significant, suggesting the rearing method did not greatly alter settling behavior. Indoor‐only tortoises dispersed at least twice as far from their release site (156.2 ± 26.3 m compared with 77.3 ± 20.6 m for combo tortoises), had larger mean use areas (3.7 ± 0.1 ha compared with 2.8 ± 0.3 ha for combo tortoises for 95% Brownian bridge movement model estimates), and greater variability in their movements than combo tortoises (daily average step length post‐emergence: 4.3 ± 0.2 m compared with 2.8 ± 0.1 m for combo tortoises). Despite differences in their movements, indoor‐only and combo tortoises had similar survival rates over the study, 51% versus 42%, respectively, during a period of extreme drought in 2021. The similarity in survival between groups gives head‐starting practitioners freedom in their rearing methods. The indoor‐only group had lower site fidelity, which should be considered when this is an undesirable trait for released tortoises.

Design of Automated Bascule Bridge and Collision Avoidance with Water Traffic

Abstract The development of movable bridges is a modern technological advancement that requires the integration of multi-disciplinary concepts such as control, automation, and design. In order to demonstrate how a collision avoidance system works, this research offers the design of an automated double-leaf bascule bridge with a pulley-rope moving mechanism and Pratt truss. The bridge is created where a settled railway or roadway intersection of a navigable stream cannot attain a steep profile. The design took into account the length, height, and width of the bridge as well as automatic ship identification and scaffold leaf movement activity for ship crossing. For the safe passage of cars on the bridge and for stopping vehicles during bridge movement, the system includes a collision avoidance control system and an automated road barrier system. After sensor adjustment, the model bridge’s performance under test produced results that were adequate, with a success rate of 100%.

Pygmy Blue Whale Home Ranges and Their Overlaps with Indonesian and Australian Marine Protected Areas: Comparison between a-LoCoH and BBMM Methods

Information on the distribution of marine migratory species is lacking, and for a long time, these species have been overlooked in the designation of Marine Protected Areas (MPAs). This study analysed the home range of pygmy blue whales (PBWs) from western Australia to eastern Indonesia to be able to assess the overlap with current MPAs. In this study, data from 11 individual PBWs tagged in the Perth Canyon were used. Two home range methods, adaptive Local Convex Hull (a-LoCoH) and Brownian Bridge Movement Model (BBMM), were performed and compared to identify core use areas and connections between these areas (i.e., migration corridors). By assessing the relative properties and visually inspecting the home ranges, 90% BBMM (home range and migration corridor) and 50% BBMM (core use area) are chosen as the best results, because they cover the connected core-use areas to a large extent. The home ranges that were covered by current MPAs were only 2% in Indonesia and 16% in Australia. Important migration corridors without current protection are in the east Savu Sea, south of Timor Island, and wider Banda Sea. It is noteworthy that comparing methods is relevant to be able to choose the most suitable method for the data used and the goal of this study. The limited overlap between the calculated home ranges and the MPAs of the Indonesian waters articulates the importance of in-depth scientific studies to be able to evaluate, implement and develop marine conservation planning.

Conservation of Bewick’s swans (Cygnus columbianus bewickii): Insights from the identification of critical stopover sites and migration corridors

Migratory birds face diverse threats during migration. Critical stopover sites (CSSs) are essential refueling and resting sites for migratory birds that ensure their complete migration and survival. Therefore, identifying bird migration patterns, routes, and critical habitats is vital for conservation. From 2018–2022, we deployed satellite tracking devices on 30 Bewick’s swans (Cygnus columbianus bewickii) wintering in China to determine their migration routes. Using a dynamic Brownian bridge movement model, we identified migration corridors, core movement areas, and CSSs for Bewick’s swans. Combining protected area databases and human settlement types, we further assessed the swans’ conservation status and human impacts on CSSs. The results showed that Bewick’s swans migrated north from their wintering grounds using one of three routes (west, middle, and east), passing through Mongolia to reach the Russian Arctic (breeding grounds) in spring. They followed similar routes during autumn to return to wintering grounds. We found a new middle route within the East Asian–Australasian Flyway (EAAF) and several northward expanded wintering sites. Our study revealed similarities and differences in the spring and autumn migrations, with longer stopover durations in spring due to migration strategies and ice conditions. Moreover, our findings identified the Inner Mongolia region, the Songnen Plain, the Bohai Rim of China, and the main streams of the Lena River and the Ob River of Russia as CSSs for Bewick’s swans. However, the conservation status of the CSSs was relatively low; and the situation was more severe in spring than in autumn, only 4.3% of the total area was protected, likely due to the distribution of farmland and urban areas. Specifically, 14.3% of the CSSs in China were in urban areas during spring, while in Mongolia and Russia this figure was less than 1%. Therefore, it is necessary to balance waterbird conservation with sustainable agriculture and urban development. This research contributes to our understanding of the migratory ecology of Bewick’s swans wintering in China. The identified migration corridors and CSSs are crucial for the future conservation of swans along the EAAF.

Spatial Ecology of an Arboreal Iguana (Oplurus cyclurus) in a Treeless Landscape.

Understanding the spatial ecology of species has important implications for conservation, as it helps identify suitable habitats and minimum requirements for biodiversity monitoring and management. The spiny-tailed lizard Oplurus cyclurus is a widespread endemic iguanid occurring in dry areas of southern and western Madagascar. While the species is known to be mostly arboreal, populations of the Isalo sandstone massif suggest local adaptation to a less forested savannah and a more exposed habitat. We radio-tracked 19 spiny-tailed lizards to investigate the species' rock-dwelling behaviour and spatial ecology at Isalo National Park. Tracked individuals showed high site and burrow fidelity, and a basking behaviour mostly tied to the accessibility of their burrow, the time of day, and their life stage. Activity peaked during the sunniest hours, while juveniles were more active than adults with unfavourable weather conditions. Despite high burrow fidelity, lizards used shelters non-exclusively, regularly changing (approx. once a week) with neighbouring burrows (average distance between burrows = 13.6 m). However, there was no obvious relation between lizards' body and/or tail size and the width and depth of selected burrows. Dynamic Brownian Bridge Movement Models estimated frequented areas over 247.8 m2 (95% isopleth), where territorial overlap is common. Our results challenge the notion that burrow-site fidelity is the sole driving factor behind space utilization in the studied population. We argue that the apparently unusual saxicolous habits imposed by habitat features (the absence of trees) may lead to local behavioural adjustments influencing antipredatory and foraging strategies, as well as intraspecific interactions.

Potential Effects of Habitat Change on Migratory Bird Movements and Avian Influenza Transmission in the East Asian-Australasian Flyway

Wild waterbirds, and especially wild waterfowl, are considered to be a reservoir for avian influenza viruses, with transmission likely occurring at the agricultural-wildlife interface. In the past few decades, avian influenza has repeatedly emerged in China along the East Asian-Australasian Flyway (EAAF), where extensive habitat conversion has occurred. Rapid environmental changes in the EAAF, especially distributional changes in rice paddy agriculture, have the potential to affect both the movements of wild migratory birds and the likelihood of spillover at the agricultural-wildlife interface. To begin to understand the potential implications such changes may have on waterfowl and disease transmission risk, we created dynamic Brownian Bridge Movement Models (dBBMM) based on waterfowl telemetry data. We used these dBBMM models to create hypothetical scenarios that would predict likely changes in waterfowl distribution relative to recent changes in rice distribution quantified through remote sensing. Our models examined a range of responses in which increased availability of rice paddies would drive increased use by waterfowl and decreased availability would result in decreased use, predicted from empirical data. Results from our scenarios suggested that in southeast China, relatively small decreases in rice agriculture could lead to dramatic loss of stopover habitat, and in northeast China, increases in rice paddies should provide new areas that can be used by waterfowl. Finally, we explored the implications of how such scenarios of changing waterfowl distribution may affect the potential for avian influenza transmission. Our results provide advance understanding of changing disease transmission threats by incorporating real-world data that predicts differences in habitat utilization by migratory birds over time.

CONTRASTING HOME RANGE CHARACTERISTICS AND PREY OF SYMPATRIC HAWKS (BUTEO SPP) NESTING IN THE UPPER COLUMBIA RIVER BASIN

Between 2007 and 2021 we monitored adult hawks (Buteo spp.) nesting in the upper Columbia River Basin of Washington and Oregon using global positioning system (GPS) telemetry on 17 Ferruginous Hawks (B. regalis), 9 Red-tailed Hawks (B. jamaicensis), and 14 Swainson's Hawks (B. swainsoni). Our main objectives were to: (1) provide contemporary home-range estimates using fixes generated by the global positioning system to better inform protective buffers on Buteo ranges in the Columbia River Basin; and (2) describe prey analyzed from pellets collected at 47 Buteo territories. Breeding home ranges (Brownian bridge movement model, 95% isopleths) of Ferruginous Hawks (B. regalis) were substantially larger (x̄ = 378, sx = 133 km2) than those published previously, as were home ranges of Swainson's Hawks (x̄ = 276, sx = 146 km2) and Red-tailed Hawks (x̄ = 28, sx = 12 km2). Diets of Ferruginous Hawks on the study area were dominated (60%) by Northern Pocket Gophers (Thomomys talpoides), whereas Swainson's Hawks primarily (83%) ate grasshoppers (Apote notablis and Melanoplus spp.). Red-tailed Hawks ate a less-specialized diet of reptiles (40%), mammals (38%), and birds (13%). We provide models that show the probable degree of protection afforded by different-sized buffers when applied to species-specific home ranges and core areas for hawks in the Columbia River Basin.

Sharing habitat: Effects of migratory barnacle geese density on meadow breeding waders

1.Following targeted conservation actions most goose populations have increased. The growing goose populations caused an increase in human-wildlife conflicts and have the potential to affect nature values. As meadow birds, including meadow-breeding waders, were declining throughout Western Europe, the possible negative effect of rising numbers of foraging barnacle geese on their breeding success has been questioned.2.We used GPS-transmitter data to measure the density of foraging barnacle geese during daylight hours. Using dynamic Brownian Bridge Movement Models (dBBMM), we investigated the effect of barnacle goose density on the territory distribution of five wader species, and on nest success of the locally common Northern lapwing. We used model selection methods to identify the importance of barnacle goose density related to other environmental factors.3.Our results showed an insignificant positive association between barnacle goose density and nest territory density of the Northern lapwing and common redshank. Barnacle goose density had no influence on territory selection of godwit, oystercatcher and ringed plover. We did, however, find a negative correlation between barnacle geese density and the nest success of the Northern Lapwing.4.We infer that either barnacle goose foraging leads to improved territory conditions for some wader species, or that both barnacle geese and waders prefer the same type of habitat for foraging and nesting. Higher barnacle goose density was correlated with fewer Northern lapwing nests being successful.5.Synthesis and application: Experimental research is needed to disentangle the causal chain, but based on our observational findings, we suggest to increase water logging that may attract both barnacle geese and wader species. Further investigation on the effects of barnacle geese on wader species is necessary to identify the cause of the negative correlation between barnacle geese density and nest success of lapwings; nest protection experiments could give further insight.

Movement ecology of exotic nilgai antelope: A threat to the re‐emergence of cattle fever ticks in the southern USA

AbstractWildlife plays an important role in the emergence of livestock diseases, and their movements can complicate disease management efforts. One of the most significant vector‐borne diseases of livestock worldwide is bovine babesiosis, spread by cattle fever ticks (CFTs; Rhipicephalus [=Boophilus] microplus and Rhipicephalus [=Boophilus] annulatus). Although CFTs were eradicated from the United States by 1943, bovine babesiosis and CFTs are prevalent in México. Recently, management of CFTs in the Texas–México region has been complicated by the presence of free‐ranging, exotic nilgai antelope (Boselaphus tragocamelus). Nilgai are abundant in this region and are competent hosts for CFTs. The goal of this study was to better understand nilgai movements and space use to inform CFT treatment strategies. We analyzed hourly locations from 40 GPS‐collared nilgai in Cameron County, TX, USA, from April 2019 to September 2020. We assigned each nilgai a movement behavior using the net squared displacement metric. We estimated nilgai home range sizes at different temporal scales (monthly, seasonally, and overall) using Brownian bridge movement models. We observed movement patterns consistent with residency (52.5%), seasonal movers (17.5%), dispersal (5%), and unclassified (25%). Resident nilgai had an average maximum axial distance of 7.8 km, while two young females made separate dispersal movements of about 40 km within a year. Overall, nilgai had large and highly variable home ranges: annual median home range estimate for females was 563 ha (range = 105–1545 ha), and for males, it was 937 ha (range = 221–1602 ha). Peak nilgai movements occurred during crepuscular hours, and median hourly movement for females was 57 m/h, and for males, it was 66 m/h. Nilgai home ranges and long‐distance movements have the potential to overlap multiple ranches, as the typical ranch size in South Texas ranges from 250 to 6000 ha. Resident nilgai were more likely to maintain local infestations of CFT. Dispersal events took place during peak tick season, demonstrating the potential for nilgai to aid in the spread of CFT. Understanding these behaviors will help the CFT Eradication Program develop more efficacious treatment strategies to treat infestations in nilgai.

Migration routes and stepping stones along the western flyway of Lesser White-fronted Geese (Anser erythropus)

Summary In 2015 and 2016 four Lesser White-fronted Geese (Anser erythropus), a globally threatened species, were caught and tagged during spring migration representing nearly 10% of the entire Swedish breeding population at the time. Two of the birds were followed over more than one season. Tracking data revealed an unexpected wide network of migration corridors and staging sites. Autumn and spring migration differed by stepping-stone sites and migration speed. So far unknown key stopover sites were discovered in Denmark, northern Germany, and Sweden. By using dynamic Brownian bridge movement models, the potential areas that Lesser White-fronted Geese used during migration are described and conservation implications spotlighted. This study provides another important piece of the puzzle describing the migration of Lesser White-fronted Geese in Western Europe.

Movement and ranging behaviour of long-nosed potoroos (Potorous tridactylus) in south-west Victoria, Australia

Context A comprehensive understanding of movements and space use can underpin the effective management of threatened species. GPS dataloggers can collect large amounts of high-quality movement data, and recent advances in statistical approaches allow for robust estimates of home range size to be generated. Until recently, technological and practical constraints have generally restricted the collection of movement data via GPS dataloggers to larger species. However, reductions in the size and weight of GPS dataloggers now allow for this technology to be applied to smaller species. Aims The aim of this study was to describe the home range and movement patterns of a nationally vulnerable, native Australian ground-dwelling mammal, the long-nosed potoroo (Potorous tridactylus), in south-west Victoria, mainland Australia. Methods We attached GPS dataloggers to 40 long-nosed potoroos between 2020 and 2022 and estimated home range size using dynamic Brownian Bridge movement models. We evaluated the influence of physiological factors such as body mass and sex on home range size and described patterns of home range overlap between and within sexes. Key results Mean home range sizes were estimated to be 13.73 ha (95% CI: 10.9–16.6) and 6.67 ha (95% CI: 5.49–7.85) for males and females respectively. Home range size scaled with body mass in males but not females, and ranges were largely overlapping – although there was some evidence of intrasexual spatial partitioning of core range areas in females. Conclusions Ours is the first application of GPS dataloggers to this species, and our home range estimates are over twice as large as other reported estimates for mainland Australia. Long-nosed potoroos may range across larger areas than previously predicted on mainland Australia. Implications This knowledge may be used to optimise the management of long-nosed potoroo populations before and after fire – a key threatening process for this species. Our study highlights the value of integrating GPS dataloggers and robust home range estimators when describing the movement ecology of a population.

Natal Dispersal of Eastern Imperial Eagles: Preliminary Results For the Central European Population

The Central European Population of the Eastern Imperial Eagle (Aquila heliaca) is located on its most western global distribution edge. After a strong decline in the last two centuries, the population recovered in the past decades not least due to extensive protection measurements. Conservation and scientific programs on international and national level were implemented in several countries, especially in Hungary, Slovakia, Austria, Czech Republic, and Serbia. In frame of these activities imperial eagle were tagged by satellite transmitter since 2003 in several projects by different organisations of the region. In the current presentation we show preliminary results of an analysis of the natal dispersal movements of the immature birds of this residential population of Eastern Imperial Eagles. Therefore, more than 14 million data points of more than 130 individuals were available and analysed. We defined start of natal dispersal as the point when the young birds left their natal territory (5 km from natal nest) for at least 10 consecutive days. Because of high individual variability, we decided to classify the end of dispersal manually as the time the bird became territorial for the first time. We analysed movement pattern for the whole period of natal dispersal as well as for different life stages/age classes. Therefore we distinguished between breeding (1.2–30.9) and non-breeding season (1.10–30.2) for each year of life of the birds. It turns out that daily travel ranges are higher during the breeding season than outside the breeding season and that activity decreases over the years until the birds start establishing a territory. Furthermore, we estimate utilization distribution (UD) by calculating a dynamic Brownian Bridge Movement Model (dBBMM). Therefor in a first step, a dBBMM was calculated for each single individual. Those individual UDs were summarised up by using days of tracking as weight. The resulting UD gives an overview of distribution and space use of immature Eastern Imperial Eagles. It shows that while wide explorative flights of single birds occur, the majority of the birds stays mainly in Central Europe within the range of the breeding distribution of the population. Additional, there is a connection to the western parts of Greece and the island of Crete. The results help to enhance knowledge about habitat use and identify hotspots for further conservation efforts.