Core Activity Areas Research Articles

Area sharing among tigers in re-introduced population of Sariska tiger reserve demonstrating space crunch in Human dominated landscape

We examined the home range dynamics, dispersal patterns, and space-sharing behaviour of reintroduced tigers and their progenies in different generations in Sariska Tiger Reserve (STR) from 2018 to 2022. During the study period, the tiger population increased from four males and eight females to seven males, 11 females, and three sub-adult females. Mean home ranges were 34 ± 2 km² (SE) for female tigers (n=11) and 95 ± 6 km² for male tigers (n=10), while core activity areas (50% KDE) averaged 6 ± 1 km² for females and 23 ± 3 km² for males. Female home ranges showed a decreasing trend due to natal dispersal by sub-adults, whereas male home ranges expanded due to territorial consolidation. Instances of territorial overlap, including fatal conflicts, highlighted the competitive pressures in this human dominated landscape. To accommodate the growing tiger population and mitigate human-tiger conflicts, we recommend enhanced monitoring, relocation of villages to create inviolate spaces, and strengthening the protection regime.

Response of Guiana dolphins to the construction of a bridge in Ilhéus, Northeastern Brazil.

This study aimed to investigate whether the use of space and movements of Guiana dolphins were altered during the construction of a cable-stayed bridge at the mouth of the Cachoeira River estuary in Ilhéus, Brazil. We described and compared the visitation rate, use of space, and movements of the Guiana dolphins across two periods: before the construction began (2015-2016) and during the construction of the bridge (2017-2020). A theodolite and a total station were used to observe and record the trajectories of the dolphins. From these trajectories, we estimated the Utilization Distribution (UD) using the biased random bridge kernel (BRBK) method, the area of use, and the core area, based on the 95% and 50% BRBK density, respectively. The dolphins did not change their visitation frequency to the estuary. No significant change in area fidelity was identified by comparing the overlap of areas used during two-month periods. No change occurred in the velocity and linearity of the trajectories of the dolphins swimming close to the bridge. However, contrary to expectations, the results indicated an increase in the use of areas close to the bridge during its construction. This may have been caused by the change in the distribution of their prey in the estuary due to the emergence of a sandbank near the bridge. Bridge construction work seems not to have directly affected the Guiana dolphins' use of the area, but the impact of the construction on the local topography has changed their areas of use and core areas of activity.

Advancing spatial analysis of invasive species movement data to improve monitoring, control programs and decision making: feral cat home range as a case study

Context Many invasive animals are typically active across large areas, making monitoring and control programs expensive. To be efficacious, monitoring devices and control tools need to be strategically located to maximise the probability of encounter. This requires an understanding of how the target species uses the landscape, through identifying key habitat or landscape features that are preferred and used disproportionately more frequently by the species. Spatial analysis of animal movements can help identify high use areas. Aims The variability introduced by different range calculation methods can lead to uncertainty in subsequent habitat analyses. We aimed to determine which method is superior for accurate delineation of core areas for feral cats. Methods We analysed spatial data from 35 collared feral cats across four Australian study sites between 2016 and 2019, and compared the core areas generated using seven commonly used home range estimation methods. Key results We found that the α-hull method provided a higher precision of polygon placement, resulting in lower Type I and II errors and higher conformity to landscape features than other methods. The α-hull used a single default parameter and required no subjective input, making it a more objective, superior method. Conclusions We recommend that the α-hull method be used to define core activity areas for feral cats, enabling more robust habitat analysis, and identification of key habitat and landscape features to strategically target for monitoring and control programs. Implications This strategic approach could significantly improve cost efficiencies, particularly where existing management is widely dispersed, and core activity areas are clumped.

Microhabitat characterization in the home range of the Mule deer (Odocoileus hemionus) in arid zones

Knowing the home range of a species helps to identify the resources it needs to survive and reproduce and how this behavior is expressed spatially. Within home ranges, core areas are the sites where the main resources are abundant. The microhabitat is a spatial area composed of variables that can affect individual behavior. In this sense, the characterization of this inner part of the home range can contribute significantly to understanding the elements that these areas offer compared to the rest of the habitat of a population. This work characterized the home range and areas outside it, as well as the core areas of female mule deer on a microhabitat scale in the Chihuahuan Desert, México. The structure and composition of the vegetation were characterized according to three habitat use hierarchies: interior of the core areas and zones within and outside the home ranges of seven female mule deer. A Principal Component Analysis (PCA) was performed, and a hierarchical clustering was used to relate the variables. The variation in structure and composition in each hierarchy was evaluated by performing multivariate permutation tests. Twenty-five plant species were recorded in the transects. The PCA showed the most similar use hierarchies are the core and home range inner areas. The core area presents higher density and cover-dominance values, and the zone outside the home range showed high values of distance to the individual closest to the central point and greater variation in this parameter. The MANOVA indicated a significant variation in vegetation structure and composition in relation to use hierarchies. Significant differences in vegetation structure and composition were found at the microhabitat level between the core area of activity and the zones within and outside the home range. The core area has a greater structural complexity of vegetation, with greater plant coverage-abundance and density; this suggests that the core area is located in a more competitive and saturated environment. Outside the home range, the microhabitat has greater spatial heterogeneity of vegetation, with greater distance and variation of plant cover. Future research could address the spatial (micro-macro) and temporal scales to better understand the ecological dynamics of the species in different habitat use hierarchies.

A Symmetrical Double Step-Down Converter With Extended Voltage Conversion Ratio

The Hybrid DC-DC converter, especially with multiple inductors targeting high current delivery, has the advantages of high efficiency and power density with a large voltage conversion ratio (VCR), due to the combination of the benefits of both switched-capacitor-based and inductor-based buck converters. However, a higher number of inductors means that the energizing time for each inductor has more limitations, resulting in a relatively narrower VCR range. To reduce the conduction loss and extend the voltage conversion ratio scope, this paper presents a symmetrical double step-down (SDSD) converter with a VCR range up to 1/3, regulating an output voltage interval of 0.5 V-0.8 V from a 2.7 V-4.2 V Lithium-ion battery. This converter, implemented in 65 nm CMOS, occupies a core active area of 1.53 mm2. This work obtains 86.5% peak efficiency and 326 mA/mm2 maximum current density, with an effective switching frequency of 3 MHz.

Spatial ecology meets eradication of feral cats on Auckland Island

Restoration initiatives of ecosystems transformed by human actions require optimisation of eradication measures of introduced species, particularly in fragile insular ecosystems. We studied aspects of the spatial ecology of introduced feral cats (Felis catus) on subantarctic Auckland Island of New Zealand to assist eradication efforts of pests from this remote, biologically rich island. Firstly, we estimated home range sizes and identified core areas of activity based on movement-rooted dynamic Brownian bridge models.

Research and analysis of the effect between the power level and economy on the lead-based modular nuclear power reactor

The fast reactor is gradually being paid attention to in nuclear power due to a better breeding effect, and its economy is also directly followed. Due to the restriction of the core power density, the core power level is directly related to the volume of the core active area. When the power level and the volume of the core gradually increase, the mass of uranium and 235U in the core at the beginning of life will gradually increase on the basis of a critical uranium inventory. At the same time, due to the gradual increase in the breeding effect, the utilization rate of uranium resources at the end of life will gradually increase. Due to the characteristics of the large critical uranium mass and high breeding effect, the mass of uranium and 235U in the low power level core at the beginning of life cannot be further reduced because of the critical uranium inventory. The lifetime of the high power level core should be extended to use the wealthy reactivity of the core because of the improvement in the breeding effect. However, due to the requirements of the nuclear power refuel time and the limitation to fuel consumption, the breeding effect brought by the improvement in the core power level and the size of the active zone may be less effective. In this article, the power level and economy of lead-based modular nuclear power are analyzed, and the economy of different power level fast reactors with 2,000 EFPD lifetime such as 100 MWt, 300 MWt, 500 MWt, 700 MWt, and 1000 MWt thermal power is designed and analyzed. By analyzing the invention of uranium and 235U and the fuel utilization of different core schemes, the best economic analysis of the single reactor power of the current lead-based modular reactor is proposed and the foundation of the lead-based modular nuclear power is provided.

Advancing global health and the sustainable development goals through transdisciplinary research and equitable publication practices

Advancing global health and the sustainable development goals through transdisciplinary research and equitable publication practices

Delineating and characterizing critical habitat for the Eastern Pacific olive ridley turtle (Lepidochelys olivacea): Individual differences in migratory routes present challenges for conservation measures

The effective conservation of highly migratory marine species is only possible if core areas of activity and critical habitat can be identified within the vast and dynamic oceanic environment and later on used to delineate marine protected areas (MPAs). However, gathering population-level data and identifying universal patterns within a species or population can be difficult when only a small sample size exists and individuals are not ecologically interchangeable. In addition, the open ocean beyond the Exclusive Economic Zone (EEZ) of a country is considered the high-seas and is not part of any jurisdiction and therefore challenging to govern by laws. Granting protection to species using these waters is sometimes virtually impossible. Another challenge is the dynamic nature of the oceanic environment. MPAs are usually based on spatially explicit and static areas, but migratory routes can shift following available food, currents, and temperatures or else, potentially rendering designated areas useless. The red-listed olive ridley turtle is known for its nomadic migratory and feeding behavior and a divergent nesting strategy among females. Our study used two approaches to identify critical habitats for the population nesting in Costa Rica and feeding in the Eastern Tropical Pacific. One was based on a static Kernel Density Approach to identify core areas. The other was a habitat preference model that took into account changing environmental variables such as sea surface temperature and chlorophyll-a concentrations. We were able to identify core areas at the population level by pooling two datasets and increasing our sample size. Our habitat preference model showed a high correlation of olive ridley presence with all tested environmental variables, except chlorophyll-a concentration. Our results reveal that olive ridleys use mainly regions that fall within EEZs and, therefore, the jurisdiction of six countries in Central America and provide an essential conservation tool.

Seasonal space use and habitat selection in magpie geese: implications for reducing human‐wildlife conflicts

AbstractNegative interactions between waterbirds and people are increasing. Waterbirds feeding on agricultural crops cause significant losses to farmers worldwide, but so far most research to address these conflicts has been conducted on migratory species in the temperate northern hemisphere. We investigated the space use and habitat selection of the magpie goose (Anseranas semipalmata), a taxonomically distinct waterbird endemic to Australia and southern Papua New Guinea. In tropical northern Australia, magpie geese are protected but are increasingly persecuted by farmers to protect crops during the late dry–early wet season (~Sep–Jan), a bottleneck of natural resources for waterbirds in the monsoonal tropics. Using satellite telemetry of 38 geese spread across 3 seasons (2016–2017, 2017–2018, 2018–2019), we evaluated daily and seasonal space use, individual site fidelity, and habitat selection to determine the extent of use of agricultural fields by geese, and the spatiotemporal scales at which management should be undertaken. Geese used relatively small daily areas (x̄ = 8.2 km2) consistently throughout the late dry–early wet season, and repeatedly used agricultural fields, forested bushlands, and local wetlands. Geese used comparatively large seasonal areas (x̄ = 219.5 km2) encompassing several agricultural areas, and had a low mean overlap between successive weekly core activity areas, indicating that site fidelity rapidly weakened over time. These results suggest that farm‐scale (<30 ha) management of geese is unlikely to be effective because hazed individuals are likely to be replaced soon afterwards. Instead, our findings suggest that goose management should be coordinated strategically at the local (~1,000 ha), or regional (~100,000 ha) scale. Farm‐level management would likely be more effective if implemented in conjunction with the creation of regional sanctuaries where geese could rest and potentially feed undisturbed away from farms. Our findings can be used by wildlife managers for optimizing the location of such sanctuaries and highlight the necessity for management to be adaptive given the opportunistic nature of the species.

Identifying habitat preferences and core areas of Amazon River dolphin activity using spatial ecology analysis

Identifying habitat preferences and core areas of Amazon River dolphin activity using spatial ecology analysis

Seasonal and age-specific dynamics of the Griffon Vulture’s home range and movements in the Eastern Rhodopes

Abstract The spatial ecology of the Eurasian Griffon Vulture (Gyps fulvus) has been a subject of scientific interest for long due to its conservation status, critical ecosystem role, gregarious lifestyle and complex foraging behavior. The trans-border Eastern Rhodope Mountain in Bulgaria and Greece holds an increasing population of the species and one of the largest on the Balkan Peninsula. We used high-frequency GPS data from 13 Griffon Vultures from this population to study their movements, home range size and its seasonal or age specific dynamics. The overall foraging home range (95% kernel) was 3,204 km2 and the core area of activity (50% kernel) was 256.5 km2. We found high seasonal variation of the home range size. Vultures were foraging over larger areas in the summer and spring but their activity was limited to four times smaller areas in winter. We found no age specific variation in the home range sizes but the non-adult vultures showed tendency to conduct exploratory movements far from the breeding colony. Our results can be used for planning conservation efforts in the areas of high importance for the species.

Habitat use and activity patterns of female Deacon Rockfish (Sebastes diaconus) at seasonal scales and in response to episodic hypoxia

We combined a high-resolution acoustic telemetry array with presence/absence receivers to conduct a preliminary study of the seasonal movements, activity patterns, and habitat associations of the newly described Deacon Rockfish (Sebastes diaconus). Eleven mature female Deacon Rockfish were tagged and monitored during an 11-month period, at a nearshore rocky reef off Seal Rock, Oregon, USA, an area of recurring seasonal hypoxia (defined as dissolved oxygen concentration [DO] < 2 mg l−1). Two tags were detected leaving the study area by day 35, indicating predation or emigration. Three tags became inactive within the array, indicating tag loss or fish death. Six “resident” fish inhabited the array for 246–326 days. Resident fish exhibited high site fidelity, small home ranges (mean 95% KDE = 4907 m2), and consistent activity patterns for the duration of the summertime high-resolution array (5 months), except during seasonal hypoxia. Resident fish were strongly diurnal in summer, with high levels of daytime activity above the bottom in relatively rugose habitat, followed by nighttime rest periods in deeper, less rugose habitat. During summertime hypoxia, resident fish exhibited less daytime activity during daytime hours with no rest periods at night, inhabited shallower water depths, and moved well away from their core activity areas on long, erratic forays. During the winter, diel patterns were less evident with higher activity levels at night (than in the summer) and lower activity levels in the day (than in the summer). We propose that some Deacon Rockfish continuously inhabit nearshore reefs throughout the year, but that daily/seasonal movement patterns, seasonally occurring hypoxia, and prey preferences for planktonic organisms influence relocation.

ОБ ЭКСПЕРТНО-ОБРАЗОВАТЕЛЬНОМ ПРОЕКТЕ «ТОЧКИ РОСТА»

The present review is concerned with the participation of an associate professor of the Institute of Post-Soviet and Interregional Studies of RSUH in the project “Points of growth”. During the project activities, A.V. Gushchin gave lectures, presentations, took part in a situational analysis. The project “Points of growth”, which is an expert and educational platform for Eurasian integration, is dedicated to the core area of activity for Institute – the study and forecasting of international, socio-political, economic and cultural processes in post-Soviet Eurasia. The program of the forum platforms provides for meetings in the format of “Dialogue on equal terms” with the leading Rus- sian and foreign experts in the field of international relations, political science and geo-economics, the diplomats, the representatives of government and busi- ness. The target audience of the project are the leaders of youth organizations, young representatives of political parties and experts in the field of interna- tional relations and Russian foreign policy, students interested in international relations and Eurasian issues. It is implemented by the Institute of Russian Abroad in cooperation with the partner organizations using a grant from the President of the Russian Federation provided by the Presidential Grants Fund. The present review contains information about the key activities of the project that took place in Pskov, Minsk and Kolomna in 2021.

Life in the suburbs: artificial heat source selection for nocturnal thermoregulation in a diurnally active tropical lizard

Abstract. The rapid expansion of urban environments invariably presents a novel series of pressures on wildlife due to changes in external environmental factors. In reptiles, any such changes in temperature are critical since thermoregulation is the key driver in the function of many physiological processes. How reptiles adapt to such changes may vary from those species that are impacted negatively to others that have the behavioural flexibility to exploit new conditions. In this paper we describe retreat site selection, movements and aspects of the thermal ecology of the African lizard Agama agama in urban environments of West Africa. In early evening lizards began movement from late-afternoon core activity areas and ascended the walls of houses for overnight retreats. A high proportion retreated to locations in groups under or on top of warm electrical panels. The thermal potential these panels offered was the attainment of body temperatures equal to or higher than the minimum preferred body temperature (PBT ≈ 36 ∘C in A. agama) and hence increased physiological performance. The lizards that took advantage of the heat sources travelled further each day to and from diurnal activity areas than individuals that spent the night high on walls but not next to heat panels. There were both potential costs (enhanced predation pressures) and benefits (impacts on thermal ecology, retreat site selection) of this behaviour for lizards living in urban environments.

Individual specialization in the use of space by frugivorous bats.

Natural populations are not homogenous systems but sets of individuals that occupy subsets of the species' niche. This phenomenon is known as individual specialization. Recently, several studies found evidence of individual specialization in animal diets. Diet is a critical dimension of a species' niche that affects several other dimensions, including space use, which has been poorly studied under the light of individual specialization. In this study, which harnesses the framework of the movement ecology paradigm and uses yellow-shouldered bats Sturnira lilium as a model, we ask how food preferences lead individual bats of the same population to forage mainly in different locations and habitats. Ten individual bats were radiotracked in a heterogeneous Brazilian savanna. First, we modelled intraspecific variation in space use as a network of individual bats and the landscape elements visited by them. Second, we developed two novel metrics, the spatial individual specialization index (SpatIS) and the spatial individual complementary specialization index (SpatICS). Additionally, we tested food-plant availability as a driver of interindividual differences in space use. There was large interindividual variation in space use not explained by sex or weight. Our results point to individual specialization in space use in the studied population of S. lilium, most probably linked to food-plant distribution. Individual specialization affects not only which plant species frugivores consume, but also the way they move in space, ultimately with consequences for seed dispersal and landscape connectivity.

Mountain hares Lepus timidus follow the green‐up wave in the pursuit of high‐quality food

Spatial patterns in animal behavior can provide insight into habitat quality and the distribution of resources. Understanding how, when, and why animals use certain areas is critical to their conservation and management. We investigated the distribution of pellets of mountain hares Lepus timidus in the Swiss Alps and compared differences between spring and autumn. 1515 pellet locations from 119 individuals (70 males, 49 females) were used. Pellets were collected from 2014 to 2019; individuals were determined using an established, non‐invasive genetic technique. We found evidence of an altitudinal shift in the occurrence of pellets from lower elevations in spring to higher elevations in autumn. This seasonal pattern is also supported by altitudinal shifts of three individual core activity areas (2 males, 1 females) and by higher hare activities at the high plateau in autumn. We conclude that the annual ‘wave’ of greening from lower to higher elevations, which correlates with forage availability and quality, explains this shift.

A 15-Gb/s 0.0037-mm² 0.019-pJ/Bit Full-Rate Programmable Multi-Pattern Pseudo-Random Binary Sequence Generator

This brief presents a compact low-power programmable multi-pattern pseudo-random binary sequence (PRBS) generator. It is capable of producing 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> - 1, 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> - 1, 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">23</sup> - 1 and 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sup> - 1 test patterns to meet multiple testing requirements. To reduce power and area, the full-rate architecture with the truly-single-phase clock logic (TSPC) D-flip-flops (DFF) instead of the current-mode logic (CML) DFF is adopted. The multiplexer (MUX) merged TSPC DFF is proposed to avoid the delay of the MUX in conventional multiple pattern PRBS generators. Hence, the critical path delay is reduced, and thus, the maximum data rate can be improved. Fabricated in a 40-nm CMOS process (260-GHz <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> f_T</i> ), this PRBS occupies a core active area of 0.0037 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and operates at a maximum data rate of 15 Gb/s. The measured power consumption is 8.778 mW with 1.1-V supply. The figure-of-merit (FoM) is 0.019 pJ/bit at the pattern length of 2 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">31</sup> - 1.

Urban fringe dweller: the European red fox (

The spatial ecology of the European red fox in urban environments has not been widely studied in Australia. The spatial organisation and habitat selection of red foxes in coastal south-east Queensland was investigated using the GPS data from 17 collared foxes from seven putative fox families. Home range and core activity areas were calculated using 95% (KDE95) and 50% (KDE50) kernel density estimates respectively. Mean KDE95 home range size was 198 ha, and the mean core (KDE50) use area was 34 ha. Habitat selection, based on four broad habitat classes – Beach, Dunes, Urban and Green Space – was assessed using compositional analyses. At both 2nd order (study site) and 3rd order (home range) habitat selection, urban space was overwhelmingly the least preferred habitat in the study area despite being the most extensive habitat type. The unusual findings of this study contribute to a broader understanding of the ecology of this previously unstudied fox population.

A 0.65-V 12-16-GHz Sub-Sampling PLL With 56.4-fsrms Integrated Jitter and -256.4-dB FoM

This article presents a low-voltage (LV) sub-sampling phase-locked loop (LVSSPLL). The architecture of hybrid dual-path loop-based SSPLL is proposed to mitigate the issue of limited output voltage range of LV charge pump (CP). Four LV building blocks, including a proportional path sub-sampling CP (SSCP), an integral path SSCP, an LV sub-sampling phase detector, and an LV digitally controlled capacitor array in the LC -based voltage-controlled oscillator, are proposed to simultaneously reduce the PLL integrated jitter and the jitter variation over supply voltage variation. Fabricated in 40-nm CMOS process with a core active area of 0.24 mm2, the LVSSPLL operates at 0.65-V supply and achieves 12–16-GHz tuning range, 56.4-fs integrated jitter at 14 GHz, 7.2-mW power consumption, and −256.4-dB figure-of-merit (FoM). The measured integrated jitter variation is less than 14.5 fs within the supply voltage range from 0.62 to 0.7 V, which shows robustness over supply voltage variation.