Radio Tracking Research Articles

Design of Antenna Fields for HF Band Transmitting Radio Centers Based on Ultra-Wide-Band Antenna Systems

The current technical condition of antenna fields used in short-wave stationary transmitting radio centers is considered. The basic requirements for antenna systems used in radio centers to allow effective operation on routes having a length of 100‒5000 km are formulated. Models for the most common types of HF-band antenna systems constructed using electrodynamic modeling methods, which include logoperiodic, rhombic horizontal double, symmetrical horizontal vibrator, are described together with their energy and non-energy characteristics. Designs for a modified version of an ultra-wide-band logoperiodic structure and active phased array operating in the frequency range of 2–30 MHz are presented. Energy and non-energy parameters of existing and modified antenna systems proposed for replacement are compared. Presented results of track tests using existing and prospective antenna systems operating on a real object include an assessment of the effectiveness of each system on an average-length radio track (2100 km). The developed approach to constructing a high-frequency path of a transmitting radio center using ultra-wide-band pyramidal curved logoperiodic and pin antennas is based on calculated and experimentally obtained results. Active phased antenna arrays with controlled directional patterns developed on their basis are presented along with an appropriate antenna field layout variant.

How do we sleep while our beds are burning? Impacts of the 2019–20 mega-fires on a rainforest dependent species – the Golden-tipped Bat Phoniscus papuensis

ABSTRACT The Australian summer of 2019/20 was impacted by megafires of a magnitude and severity never previously recorded. Whilst low severity fire has positive benefits for increased insectivorous bat activity and diversity, little information is available on the impact on rainforest specialised clutter dependant species such as the Golden-tipped Bat Phoniscus papuensis. Our aims were to assess the effects of fire on occupancy of habitat across the geographic range of P. papuensis in NSW, to determine the smaller scale effects of fire on use of diurnal roosts in rainforest through radio tracking and to trial the use of artificial structures to temporarily increase roost availability in burnt habitat. We observed that widespread fire encroaching on rainforest has a negative association with occupancy by P. papuensis, with this metric ~78% lower than in unburnt forest. In burnt areas, P. papuensis preferentially used unburnt refugia for their roosting sites in suspended bird nests and the loss of these habitat structures likely contributes to the disappearance of P. papuensis from the landscape. Artificial roosts were not used in the short-term (< 2 years post fire) and do not appear to be a feasible management tool. With the increasing frequency and extent of wildfires the most important factor for P. papuensis to persist in the landscape into the future is the protection of its habitat through ensuring sensitive management of large tracts of connected rainforest to help buffer against the encroachment of future mega-fires.

Individual tracking reveals long-distance flight-path control in a nocturnally migrating moth.

Each year, trillions of insects make long-range seasonal migrations. These movements are relatively well understood at a population level, but how individual insects achieve them remains elusive. Behavioral responses to conditions en route are little studied, primarily owing to the challenges of tracking individual insects. Using a light aircraft and individual radio tracking, we show that nocturnally migrating death's-head hawkmoths maintain control of their flight trajectories over long distances. The moths did not just fly with favorable tailwinds; during a given night, they also adjusted for head and crosswinds to precisely hold course. This behavior indicates that the moths use a sophisticated internal compass to maintain seasonally beneficial migratory trajectories independent of wind conditions, illuminating how insects traverse long distances to take advantage of seasonal resources.

GPS Technology Reveals Larger Home Ranges for Immature Gopher Tortoises

Movement data and estimation of home-range sizes provide insight into the types and amount of habitat needed to support wildlife populations, which is critical for conservation planning. Gopher Tortoises, which are important ecosystem engineers and keystone species across the southeastern United States, are experiencing ongoing population declines and warrant additional habitat protection and management throughout their range. Conservation assessments for Gopher Tortoises are currently limited by scant knowledge of the ecology of younger age classes. We implemented a short-term study of immature Gopher Tortoise spatial ecology at Archbold Biological Station (ABS), Florida to determine home-range size, movements, and activity levels of 3–7-yr-old tortoises. We used GPS technology to obtain high-resolution temporal tracking data (approximately 10-fold increase compared with the radio tracking frequency in prior studies). Despite the relatively short duration of our study (≤40 d), immature Gopher Tortoises (n = 6) at ABS had home-range sizes ranging from 0.38 to 1.46 ha, which are approximately 6.6-fold larger than previously reported annual home-range estimates. Tortoises also left their burrows more often (4.0 ± 3.2 SD times per day) and for longer duration (31.5 ± 10.6 SD min per emergence) than in studies conducted elsewhere (1.6 times and 18.8 min, respectively). Our results illustrate the importance of employing new technologies to track previously difficult-to-observe life stages and improve conservation efforts for imperiled species.

Phantom Design and Verification Enabling Effective Antennas for Bird Tracking Technology

Advances in miniaturized radio tracking technology are helping to revolutionize the field of wildlife biology, especially with respect to studies of small birds. However, development of antennas for animal tracking applications often fails to formally account for the effects of the animal’s body on signal transmission. This letter describes an electromagnetic phantom that accurately represents a small bird. The phantom is validated with empirical measurements and can be easily scaled to represent larger or smaller bird species.

Frequency-dependent Ganymede’s tidal Love number [formula omitted] detection by JUICE’s 3GM experiment and implications for the subsurface ocean thickness

Ganymede will be the first icy satellite in the Solar System orbited by a spacecraft, ESA’s JUpiter ICy moons Explorer (JUICE). JUICE launch is scheduled for April 2023 and the arrival at Ganymede is foreseen in 2035.Thanks to the advanced Ka-band radio tracking system, the Geodesy and Geophysics of Jupiter and Galilean Moons (3GM) experiment aboard the mission will provide range and range-rate measurements that will be used to infer the static (up to degree 35–45) and time-varying gravity field and the internal structure of the moon. Ganymede is subject to tidal deformation, which periodically modifies its gravity field. The larger contribution to the time-varying gravity is due to the tidal interaction with Jupiter, modulated by the eccentricity and the inclination of the moon’s orbit. In addition, Ganymede also experiences a lower amplitude time-varying tidal interaction with Io, Europa and Callisto. To a good approximation, the corresponding gravitational signals are periodic and they contain several harmonics of the fundamental synodic frequencies. The elastic response of Ganymede is expected to be frequency-dependent as well. In this work we describe a procedure to estimate the Ganymede’s tidal Love number k2 at different frequencies in the orbit determination process of the 3GM experiment, supported by numerical simulations. Finally, we show that 3GM measurements can be used to characterize the interior structure of Ganymede, providing a tight constraint on the subsurface ocean thickness. The ocean density can be also constrained, but with a lower precision.

The ranging, habitat selection, and foraging ecology of an endangered small desert mammal, the sandhill dunnartSminthopsis psammophila

AbstractThe conservation of threatened species often requires an examination of home range, foraging preferences, and diet. We used radio tracking, global positioning system data loggers, and fecal pellet analyses to study the nocturnal ecology of an endangered desert mammal, the sandhill dunnart, Sminthopsis psammophila. Twenty-four individuals were tracked between 2015 and 2018. The mean home range area of S. psammophila was 70 ha (100% minimum convex polygon). Reproductive males had a mean home range of 148 ha, whereas the ranges of all other groups were comparatively smaller. Sminthopsis psammophila preferred dense, long unburned foraging habitats. There was no effect of weather (excluding extreme cold/rain) on nocturnal ranging behavior. Ants comprised a significant proportion of the diet of S. psammophila and S. hirtipes, whereas S. dolichura consumed a broader range of prey. By integrating foraging and dietary analyses, we provide new insights to improve the conservation management of one of Australia’s least studied but most threatened marsupials.

Automated radio tracking provides evidence for social pair bonds in an obligate brood parasite

Social monogamy predominates in avian mating systems, but this strategy seems unlikely among brood parasites, where the emancipation from parental care should lead to an increase in numbers of mates for both sexes. Despite this, there is great diversity in mating systems in brood parasitic birds. The Screaming CowbirdMolothrus rufoaxillarisis a brood parasite that specializes almost exclusively on one host, the Greyish BaywingAgelaioides badius. Field observations and a radio telemetry study have indicated that male–female pairs spend a great deal of time together through the day, suggesting that they may be socially monogamous. We tested the hypothesis of social monogamy by radio‐tracking male and female Screaming Cowbirds using an array of automated radiotracking receivers to collect data on spatial behaviour and social mating system. Monogamous pair bonds were recorded through social network analysis. These bonds endured throughout the entire breeding season, with males and females remaining associated throughout the day. In accordance with the hypothesis, paired Screaming Cowbirds spent significantly more time in proximity to their mates than to other conspecifics of the opposite sex, and had similar home‐ranges. Social monogamy in the Screaming Cowbird differed markedly from the social polygyny/promiscuity exhibited by the sympatric congener Shiny CowbirdMolothrus bonariensis, a generalist brood parasite.

Home ranges and activity of Garden Dormice in the Harz Mountains, Germany

For the conservation of endangered species, a good knowledge of their biology is essential. However, due to the secluded lifestyle and nocturnal activity of the Garden Dormouse (Eliomys quercinus), comprehensive research on these small mammals is difficult, resulting in a lack of data. Little is known about the habitat requirements of Garden Dormice in forest habitats. Radio tracking was used to analyze movement patterns to identify specific features of their habitat in the Harz Mountains National Park in Germany (~700 m a.s.l.). Four individuals (2 females, 2 males) were tracked during 11 weeks from May until September 2021. Home ranges were calculated using minimum convex polygon (MCP) and fixed kernel density estimation (KDE) methods. Home range sizes (100% MCP) of males were between 0.58 ha and 7.62 ha and of females between 3.63 ha and 6.39 ha. The size of the core areas (65% KDE) was 0.25 ha - 3.08 ha for males and 1.94 ha - 6.18 ha for females. Whereas the start of their daily activity did not correlate with sunset, the end of activity was associated with sunrise. The females never switched their nesting sites, but the males used 7 -10 nesting sites. Nesting sites were located between boulders and inside deadwood piles. Deadwood is an important habitat for insects which serve as food for Garden Dormice (and other small mammals). To this species in its natural habitat it is necessary to sustain deadwood in forests.

Habitat use and movement of Garden Dormice in the Harz Mountains, Germany

The Garden Dormouse (Eliomys quercinus) is an example of an endangered species with a distribution focus in Germany. Little is known about its habitat use and movements. Radio tracking is a common method used to analyze movement patterns to identify specific habitat requirements. During 11 weeks from May until September 2021, we tracked four individuals (2 females, 2 males) in the Harz Mountains National Park (~700 m a.s.l.). The study area was characterized by a predominance of rocks and spruce. Within one hour, males moved a distance of up to 173.95 m, females covered a maximum distance of 155.62 m. We analyzed whether a hiking trail cutting through the study area represented a potential barrier for the movement of these animals. Three individuals were tracked crossing the path up to 4 times a night. Raspberry bushes along the path were a potential incentive for crossing. A dense rocky cover and a well-developed shrub layer with raspberry bushes within spruce woodlands seem favorable to the presence of Garden Dormice. For the conservation of this species, it is necessary to protect similar habitats. To connect areas with populations of garden dormice, it may be important to encourage bushes with wild fruits among forest edges and pathways.

Drone-Based Position Detection in Sports-Validation and Applications.

Radio and video-based electronic performance and tracking systems (EPTS) for position detection are widely used in a variety of sports. In this paper, the authors introduce an innovative approach to video-based tracking that uses a single camera attached to a drone to capture an area of interest from a bird’s eye view. This pilot validation study showcases several applications of this novel approach for the analysis of game and racket sports. To this end, the authors compared positional data retrieved from video footage recorded using a drone with positional data obtained from established radio-based systems in three different setups: a tennis match during training with the drone hovering at a height of 27 m, a small-sided soccer game with the drone at a height of 50 m, and an Ultimate Frisbee match with the drone at a height of 85 m. For each type of playing surface, clay (tennis) and grass (soccer and Ultimate), the drone-based system demonstrated acceptable static accuracy with root mean square errors of 0.02 m (clay) and 0.15 m (grass). The total distance measured using the drone-based system showed an absolute difference of 2.78% in Ultimate and 2.36% in soccer, when compared to an established GPS system and an absolute difference of 2.68% in tennis, when compared to a state-of-the-art LPS. The overall ICC value for consistency was 0.998. Further applications of a drone-based EPTS and the collected positional data in the context of performance analysis are discussed. Based on the findings of this pilot validation study, we conclude that drone-based position detection could serve as a promising alternative to existing EPTS but would benefit from further comparisons in dynamic settings and across different sports.

Optimizing trilateration estimates for tracking fine-scale movement of wildlife using automated radio telemetry networks.

A major advancement in the use of radio telemetry has been the development of automated radio tracking systems (ARTS), which allow animal movements to be tracked continuously. A new ARTS approach is the use of a network of simple radio receivers (nodes) that collect radio signal strength (RSS) values from animal‐borne radio transmitters. However, the use of RSS‐based localization methods in wildlife tracking research is new, and analytical approaches critical for determining high‐quality location data have lagged behind technological developments. We present an analytical approach to optimize RSS‐based localization estimates for a node network designed to track fine‐scale animal movements in a localized area. Specifically, we test the application of analytical filters (signal strength, distance among nodes) to data from real and simulated node networks that differ in the density and configuration of nodes. We evaluate how different filters and network configurations (density and regularity of node spacing) may influence the accuracy of RSS‐based localization estimates. Overall, the use of signal strength and distance‐based filters resulted in a 3‐ to 9‐fold increase in median accuracy of location estimates over unfiltered estimates, with the most stringent filters providing location estimates with a median accuracy ranging from 28 to 73 m depending on the configuration and spacing of the node network. We found that distance filters performed significantly better than RSS filters for networks with evenly spaced nodes, but the advantage diminished when nodes were less uniformly spaced within a network. Our results not only provide analytical approaches to greatly increase the accuracy of RSS‐based localization estimates, as well as the computer code to do so, but also provide guidance on how to best configure node networks to maximize the accuracy and capabilities of such systems for wildlife tracking studies.

Toad invasion of Malagasy forests triggers severe mortality of a predatory snake

The Asian common toad Duttaphrynus melanostictus has been introduced to the eastern province of Toamasina in Madagascar, where it is feared to be having devastating effects on native communities by poisoning frog-eating predators. So far it is unclear whether the toad can invade forest habitats, and empirical evidence of its impact on native predators is lacking. We used radio tracking to investigate the spatial behaviour of adult toads in a small parcel of lowland humid forest and we quantify the disruptive effects of toad poisoning on a native frog-eating snake, the Malagasy cat-eyed snake (Madagascarophis colubrinus). We used N-mixture models to estimate the population size of cat-eyed snakes, and used the mortality events recorded in the same area to obtain an estimate of monthly mortality rate of snakes due to toad poisoning. Our results point to a drastic mortality rate of snakes that, if constant through the year, could halve the predator population, with the potential risk of local extirpation. We expect cat-eyed snake populations across rural and suburban areas of Toamasina to be severely affected by the toad invasion, and suggest that future research should investigate the effects of indirect facilitation of human-commensal rodents and the potential repercussions on human health and well-being.

Early-life experience shapes patterns of senescence in a food-caching passerine.

For many species, breeding performance increases through early adulthood followed by declines later in life. Although patterns of age-specific decline have been shown to vary between individuals, the factors that lead to this individual variation in the intensity of reproductive senescence are yet to be fully understood. We investigated whether early-life social status influenced age-related trends in the breeding performance of male Canada jays (Perisoreus canadensis), year-round residents of North America's boreal and sub-alpine forests. Shortly after young become nutritionally independent, intra-brood dominance struggles lead to one juvenile (Dominant Juvenile) remaining on the natal territory after expelling its subordinate siblings (Ejectees). First, we show via radio tracking that in our declining range-edge population Ejectees either join an unrelated pair (67%), form a breeding pair with another bird (28%) or occupy a territory alone (5%). Second, using 39 years of breeding data, we demonstrate that Ejectee males advanced laying dates and increased the annual number of nestlings until 6 years of age before declining, whereas Dominant Juvenile males advanced laying dates until 11 years and increased annual number of nestlings until 12 years of age before declining. This study documents clear variation in ageing patterns between dominant and expelled young, with implications for the role of early-life experiences and phenotypic quality in determining patterns of ageing.

Computational approaches to understanding interaction and development.

Audio-visual recording and location tracking produce enormous quantities of digital data with which researchers can document children's everyday interactions in naturalistic settings and assessment contexts. Machine learning and other computational approaches can produce replicable, automated measurements of these big behavioral data. The economies of scale afforded by repeated automated measurements offer a potent approach to investigating linkages between real-time behavior and developmental change. In our work, automated measurement of audio from child-worn recorders-which quantify the frequency of child and adult speech and index its phonemic complexity-are paired with ultrawide radio tracking of children's location and interpersonal orientation. Applications of objective measurement indicate the influence of adult behavior in both expert ratings of attachment behavior and ratings of autism severity, suggesting the role of dyadic factors in these "child" assessments. In the preschool classroom, location/orientation measures provide data-driven measures of children's social contact, fertile ground for vocal interactions. Both the velocity of children's movement toward one another and their social contact with one another evidence homophily: children with autism spectrum disorder, other developmental disabilities, and typically developing children were more likely to interact with children in the same group even in inclusive preschool classrooms designed to promote interchange between all children. In the vocal domain, the frequency of peer speech and the phonemic complexity of teacher speech predict the frequency and phonemic complexity of children's own speech over multiple timescales. Moreover, children's own speech predicts their assessed language abilities across disability groups, suggesting how everyday interactions facilitate development.

MANAGEMENT OF WOLF POPULATIONS IN THE CONDITIONS OF THE SOUTH PRIARALIE

The article discusses the basic principles of wolf management in the conditions of the Southern Priraralie. The management of wolf populations has its own characteristics. It is very important to know the spatial territorial structure of family-flocking areas. In addition, to have information about the number of indigenous areas occupied by him, the average fertility, mortality and the age structure of his populations. KEYWORDS: regulation, management, poaching, fertility, radio tracking, convention.

Eastern Black Rail (Laterallus jamaicensis jamaicensis) Home Range and Habitat Use in Late Winter and Early Breeding Season in Coastal Texas, USA

Habitat use by the Eastern Black Rail (Laterallus jamaicensis jamaicensis) in coastal Texas, USA is poorly understood. To provide data for effective management of the subspecies in Texas, home range size was estimated and habitat use was examined. From February-May of 2017 and 2018, regular locations of 13 radio-transmitted Eastern Black Rails were obtained at San Bernard National Wildlife Refuge, Texas. The mean fixed kernel home range for birds with ≥ 24 relocations was 2.3 ha, with a mean core area of 0.43 ha. Average 95% MCP home range was 0.98 ha with a mean core area of 0.12 ha. During radio tracking, an Eastern Black Rail nest was found on 19 March 2018, the earliest on record for the state. Birds used the Salt and Brackish High Tidal Marsh, Salty Prairie, and Baccharis (Baccharis spp.) Shrubland, and avoided Salt and Brackish Low Tidal Marsh. Home ranges contained a gently sloping elevation gradient suggesting the importance of on-foot access to higher ground. Protection and restoration of Salty Prairie, and Salt and Brackish High Tidal Marsh is recommended for maintaining Eastern Black Rail populations in coastal Texas.

The European Autumn Migration Pattern of the Blackcap, Sylvia atricapilla – From Faunistic Observations to a Basic Analysis of Orientation Cage Field Data

Abstract Presentation of a general pattern of migration is very difficult in the case of small passerines, especially nocturnal migrants, as the few accepted methods are inefficient here. It is difficult to follow migration visually (by visual field observations or moon watching). Classic ringing must be extremely intensive due to low or very low recovery rates, especially in Africa, Eastern Europe and Asia, which additionally rule out any reasonable estimation of the intensity of migration towards different destinations. Radar studies tell us nothing about the migration of individual species. Even the most modern methods, such as geolocation and radio tracking, are of very limited use for population studies. For these reasons, in most cases our knowledge in this area is fragmentary and insufficient for a satisfactory description of migration. In many cases only the breeding areas have been faunistically described in detail, while the winter-quarters and areas where the species is observed during migration are frequently described with less precision. The introduction of an effective method for studying local headings of migrants, using ‘orientation cages’, has made it possible to study the migration patterns of small passerine nocturnal migrants. The presented work is a case study on the migration pattern of the Blackcap, using data from orientation tests collected in autumn as part of the work of SEEN (SE European Bird Migration Network), consisting of 5,392 tests performed at 28 ringing sites in Central/Eastern Europe and the Middle East. The paper continues the discussion of the problem of applying the method to presentation of migration patterns in a geographically wide territory (Busse 2018, 2019, 2020). The hypothesis put forth by Busse (2019) that the arrival/departure heading axes are generally linear is accurate to within about one 10° sector was confirmed earlier. Here it was confirmed at the level of local patterns for the study sites. In general, the average deviation from the straight line is below 1°. However, there is some geographical variation, and this problem could be discussed when many more results of this kind become available for a few more species. Eight headings/streams of migrants are defined for the Blackcap within the area. Southward and south-eastern streams dominate in most of the study area. However, a very special, nearly longitudinal heading was found in southern Europe and the Middle East, which requires further study. Comparison of the patterns obtained from three different procedures strongly suggests that the general picture of Blackcap migration in Central/Eastern Europe and the Middle East is clear and coherent. Some variation in migration stream parameters (linearity and reversed heading share) suggests that further research in this direction should be conducted using data from other species.

Population dynamics of an island population of water voles Arvicola amphibius (Linnaeus, 1758) with one major predator, the eagle owl Bubo bubo (Linnaeus, 1758), in northern Norway

Predator–prey relationships are of great significance to ecosystems, and their effects on the population dynamics of voles and lemmings (Microtinae) in Boreal and Arctic environments have long been of particular interest. A simple ecosystem with one major prey and one major predator could be an ideal setting for a study of their interactions. This is the situation on several small islands on the coast of northern Norway just below the Arctic Circle, with populations of water voles Arvicola amphibius preyed upon by the eagle owl Bubo bubo. The population dynamics of the water vole was studied by trapping and tagging in 2003–2018, eagle owl pellets were collected for analyses, eagle owl breeding attempts were recorded, and some weather variables collected from official recordings. After having been introduced well into the study period, the number of sheep Ovis aries was also recorded. Water voles were the main prey of the eagle owl, with 89% occurrence in pellets, with an overrepresentation of adults and males. Both predation, sheep grazing and extreme weather events influenced the vole population. Predator exclusion, as happened in three summers due to an intensive radio tracking study, especially increased the number of surviving young (in particular from the early cohorts) and the mass of adults. Extreme weather events, such as flooding in summer and deeply frozen ground in winter, most significantly reduced vole populations. Sheep grazing may exacerbate the effects of predation. A similar multitude of factors may affect populations of other rodent species as well.

Comparison of light-time formulations in the post-Newtonian framework for the BepiColombo MORE experiment

The ESA/JAXA BepiColombo mission, launched on 20 October 2018, is currently in cruise toward Mercury. The Mercury Orbiter Radio-science Experiment (MORE), one of the 16 experiments of the mission, will exploit range and range-rate measurements collected during superior solar conjunctions to better constrain the post-Newtonian parameter γ. The MORE radio tracking system is capable of establishing a 5-leg link in X- and Ka-band to obtain 2-way range-rate measurements with an accuracy of 0.01 mm s−1 @ 60 s sampling time and 2-way range measurements at centimeter level after a few seconds of integration time, at almost all solar elongation angles. In this paper, we investigate if the light-time formulation derived by Moyer, implemented in JPL’s orbit determination code MONTE, is still a valid approximation, in light of the recent advancements in radiometric measurement performance. Several formulations of the gravitational time delay, expressed as an expansion in powers of GM/c 2 r, are considered in this work. We quantified the contribution of each term of the light-time expansion for the first superior solar conjunction experiment of BepiColombo. The maximum 2-way error caused by Moyer approximation with respect to a complete second order expansion amounts to 17 mm. This is at the level of accuracy of the novel pseudo-noise (PN) ranging system at 24 Mcps used by MORE. A complete second order expansion is then recommended for present and future superior solar conjunction experiments. The perturbation caused by the planets in the Solar System is considered as well, resulting in significant effects due to the Jupiter, the Earth and the Saturn systems. For these bodies the classical Shapiro time delay is sufficient. The corrections due to the Sun oblateness and angular momentum are negligible. The aforementioned considerations are valid for all superior conjunction experiments involving state-of-the-art radio-tracking measurements.