Search

Platypuses are a unique freshwater mammal native to eastern Australia. They are semi‐aquatic, predominantly nocturnal, and nest in burrows dug into the banks of waterbodies. Quantifying nesting burrow characteristics is challenging due to the species' cryptic nature. We radio‐tagged 11 female platypuses during their breeding season (September to November) on the Snowy River, located their resting and nesting burrows by radiotracking, and assessed plasma triglyceride concentration as a biomarker of egg production. We quantified and tested for differences in height and distance from water of resting and nesting burrows, as well as for differences in both canopy and ground cover in the vicinity of resting and nesting burrows in comparison with background control sites in the area. Female platypuses displayed a strong selection for trees and shrubs, placing both their resting and nesting burrows within 5 m of these features. Compared with resting females, nesting females selected to dig nesting burrows higher above the river (nesting 1.98 m ± 0.27 SE vs. resting 1.15 m ± 0.10 SE) that were also further away from water (9.10 m ± 1.08 SE vs. 4.77 m ± 0.53 SE). Camera trap footage captured mice (Mus musculus) and black rats (Rattus rattus) entering two confirmed nesting tunnels on numerous occasions. During the first 3 weeks following the onset of nesting behaviour in two platypuses, rats entered the nesting tunnel a total of eight times and 31 times. Whether this is a previously unconsidered predator by invasive species remains to be evaluated. Synthesis: Riparian vegetation is a critical component of platypus habitat, providing stability for burrows, protection from predators, retaining high bank necessary to avoid inundation of burrows, and providing organic matter for nesting material and for abundant macroinvertebrate communities. Given ongoing declines and habitat degradation across their range, riparian habitat must be conserved and restored to promote breeding and population persistence. [ABSTRACT FROM AUTHOR]

The Gran Canaria Blue Chaffinch is the rarest forest passerine in the western Palaearctic with a population reduced to a single locality, Inagua, in the west of the island. After a forest fire, some birds were established in another location and a reinforcement programme was launched with the aim of consolidating this new population. Between 2010 and 2019, 194 Blue Chaffinches were released in the pine forest of La Cumbre, in the centre of the island and at a higher altitude than the previous one. Birds of two origins were used for this action: captive-bred birds were released using "soft" release methods, and wild-caught birds from the Inagua source population were released using "hard" release methods. Survival of radio-tagged birds (20–42 days of battery life) was high and similar between the two groups. Wild-caught birds occupied 12–15 times more surface area than captive-bred birds that remained close to supplementary feeding sites. All translocated birds displayed breeding behaviour in the following breeding season, although the rate of contribution to the new population was significantly lower for wild-caught birds (21% compared to 54% for captive-bred birds). This disparity can be partly attributed to nearly one-fifth of the wild-caught birds returning to Inagua. We conclude that the establishment phase of the Blue Chaffinch reinforced program in Gran Canaria has been successful. To retain wild-caught birds and deter their return to the source population, we recommend employing methods akin to the soft-release techniques utilized for captive-bred birds. Ongoing monitoring of the enhanced population, collecting data on survival and breeding success, will enable the evaluation of the long-term success of the translocation program. [ABSTRACT FROM AUTHOR]

Post‐release monitoring is critical for assessing translocation outcomes. Yet the quality of information gained from monitoring can vary greatly, and perceived monitoring costs often results in reduced monitoring effort. Selecting cost‐effective monitoring strategies that provide high quality data are therefore important for assessing translocation outcomes and making informed management decisions.To compare how monitoring strategy affects information gained, we monitored a toutouwai/North Island robin (Petroica longipes) reintroduction in Aotearoa New Zealand, based on monitoring objectives of determining survival, site fidelity and whether the extent of management was large enough to protect dispersing individuals. We compared how these objectives were met through four monitoring strategies: (1) comprehensive surveys with ground radio telemetry and playback; (2) aerial drone telemetry; (3) dedicated playback by trained surveyors and (4) opportunistic playback by predator control contractors. We undertook a viewshed analysis to determine search coverage of each strategy and compared detection rates, efficiency and cost.Comprehensive ground telemetry and playback, while costly, covered the largest area and provided the most accurate data on dispersal, survival and the translocation outcome. In comparison, opportunistic playback monitoring detected substantially fewer individuals, giving a false impression of low site fidelity and survival and a failed translocation. Although drone telemetry had considerable site‐specific limitations, which limited its effectiveness during our study, it was the most cost‐effective with a high detection rate and low search effort.Synthesis and applications: Our study shows the value of intensive monitoring in facilitating management decisions for wildlife translocations. Comprehensive telemetry and playback, while costly, were invaluable for gaining high quality information on the translocation outcome. Without suitable monitoring, reintroduction outcomes can be difficult to assess and potentially result in unnecessary, ineffective or overly expensive management actions. We recommend that monitoring intensity and methodology should reflect the site, species and level of uncertainty regarding the translocation outcome. Prioritising monitoring can help reduce long‐term costs, increase quality of information gained and allow for more informed management decisions that can improve subsequent translocation outcomes. [ABSTRACT FROM AUTHOR]

One of the conservation efforts for the Komodo Dragon (Varanus komodoensis) is the translocation of the Komodo. Six juvenile captive-bred Komodo Dragons were translocated from Bogor to Wae Wuul Nature Reserve, East Nusa Tenggara Province, on 23rd September 2023. This research aims to calculate and describe home ranges total daily movements and the habitat conditions of Komodo Dragons. The research was carried out at the Wae Wuul Nature Reserve using the radio tracking method for 11 days, as most of the translocated Komodo Dragons could only survive in the short term. Results showed that translocated Komodo Dragons tend to stay near the initial release location. The average total daily movement translocated Komodo Dragons was 424.53 m day–1 with an average home range of 34.11 ha and an average core area of 8.20 ha. The habitats used by Komodo Dragons are savanna and monsoon forests dominated by bushes and trees. The presence of feral dogs and vehicle road access have the potential to pose a threat to the translocated Komodo Dragons. [ABSTRACT FROM AUTHOR]

Understanding a species' distribution is vital for making sound conservation and management decisions. Secretive behaviors and complicated seasonal movement patterns have made range delimitation surprisingly elusive for some North American birds, including the Northern Saw-whet Owl (Aegolius acadicus). Despite being among the most common of North American forest owls, only the species' breeding range is well demarcated. This has resulted in the species historically being considered a "northern" bird, with eastern migratory and nonbreeding ranges extending only as far south as central Missouri and eastern Tennessee. Recent banding efforts have shown that saw-whet owls are fall migrants much farther south. We extend this work by investigating stopover duration and nonbreeding habitat selection during 2 winters at the edge of the species' southern distribution in the Ozark Highlands of northwest Arkansas. We used radio telemetry to track 27 owls, with 17 individuals detected at least once post-release (n = 54 surveys and 131 total detections). Length of stay in the study area was most influenced by year—birds remained an average of 3.6 weeks longer during an irruption year—and our data suggest that the species uses the Ozark Highlands for both nonbreeding residency and brief stopover periods. During the 2 year study, 37% of marked owls were winter residents, 26% remained in the area temporarily, and 37% were not redetected. Winter habitat preferences of saw-whet owls in the southeast are consistent with what is known about the species in its more northernly range, with birds selecting conifers on south-facing slopes in areas with an open understory. Overall, our results suggest that saw-whet owls are not rare fall migrants and winter residents in Arkansas as was previously assumed, and more generally, are likely underappreciated winter predators in southern pine ecosystems. [ABSTRACT FROM AUTHOR]

Background: Automated radio telemetry (ART) systems enable high-temporal resolution data collection for species unsuited to satellite-based methods. A challenge of ART systems is estimating the location of radio tagged animals from the radio signals received on multiple antennas within an ART array. Localisation methods for ART systems with omni-directional receivers have undergone rapid development in recent years, with the inclusion of machine learning techniques. However, comparable machine learning methods for ART systems with directional antennas are unavailable, despite their potential for improved accuracy and greater versatility. To address this, we introduce an open-source machine learning-based location fingerprinting method for directional antenna-based ART systems. We compare this method to two alternative localisation approaches. Both alternatives use relative signal strengths recorded among multiple antennas to estimate the signal's angle of arrival at each receiver. In the 'biangulation' approach, the location is estimated by finding the intersection of these angles from two receivers. In contrast, the 'linear regression' approach uses a linear regression model to estimate the distance from the receiver along the angle of arrival, providing a location estimate. We evaluate these methods using an ART data set collected for the southern black-throated finch (Poephila cincta cincta), in the Desert Uplands Bioregion of Queensland, Australia. Results: The location fingerprinting method performed slightly better than the best performing alternative, the linear regression method, with mean positional errors of 308 m (SE = 17.7) and 335 m (SE = 18.5), respectively. The biangulation method performed substantially worse, with a mean positional error of 550 m (SE = 42.9, median = 540 m). Improved accuracy was observed with shorter distances between transmitters and receivers, higher signal strengths, and a greater number of detecting receivers, suggesting that increasing receiver density improves localisation accuracy, albeit with potential trade-offs in system coverage or cost. Furthermore, shorter pulse intervals of transmitters resulted in greater accuracy, highlighting the trade-offs among battery life, transmitter weight and radiative power. Conclusions: The open-source location fingerprinting method offers an improved and versatile localisation approach suitable for a wide variety of ART system designs, addressing the challenge of developing study-specific localisation methods using alternative approaches. [ABSTRACT FROM AUTHOR]

The mortality rate of long-distance migrants is known to peak in the period between fledging and completing the first year of life. Our understanding of this sensitive life stage, however, lags behind our understanding of determinants of nestling success (at least for temperate breeding birds). Here we collect diverse data (morphometrics, phenology, nest videos, radio tracking detections) on two generations of a long-distance migrant (the Purple Martin, Progne subis). We examine multiple life stages, to understand how in-nest conditions may carry over to the post-fledge period. Our data show that an earlier first-egg date is associated with higher parental quality as determined by their tracked movements and provisioning effort. Despite high variability in first-egg date, the duration of the nestling phase was approximately consistent between nests, with fledge-date and date of fledgling departure from the breeding grounds highly constrained by a relatively fixed duration of nestling development. Offspring of early-nesting parents fledged in better body condition, as evidenced by their larger wing chord measurements. Given the fixed nesting duration, this higher parental quality in early nesters led to early-season nestlings having the dual advantage of elevated body condition and early departure dates—two known predictors of first migration survival in this species and many others. Our work illustrates a potential carry-over effect from the nestling phase to fall-migration, and provides a useful example of linking diverse data sets across multiple life stages to extend our knowledge of breeding success to the less-understood post-breeding phase. [ABSTRACT FROM AUTHOR]

The hazel dormouse is mainly an arboreal species with nocturnal habits that, in northern European countries, moves down to the ground to hibernate in the autumn where they stay until spring at locations not well understood. To prepare for hibernation, dormice accumulate fat reserves necessary to maintain vital bodily functions when food supply is lower and the energy cost of staying active exceeds the amount of energy that can be harvested in their habitat. Little is known about the hibernation ecology of hazel dormice or where they go in the winter. In this study, different methods to identify dormouse hibernacula were used: telemetry, systematic searches, and wildlife detection dogs. The movements of 31 individuals prior to and during hibernation were observed using radiotelemetry. Weight measurements of eight wild hazel dormice were recorded during the hibernation period and the rate of weight loss of each individual calculated as proportion of body mass per day. A total of 44 hazel dormouse hibernacula were identified: 24 by telemetry, 20 by systematic searches and none by wildlife detection dogs. Telemetry results indicated that dormice selected sites for their hibernaculum within 43m (SD=30) from the place where they were captured while active, suggesting that hibernation normally takes place within their home range. The timing of hibernation varied amongst individuals, with some dormice remaining active and feeding throughout the month of December. On average dormice lost 0.47% of their body mass per day during hibernation bouts. Despite dormice hibernating largely in leaf litter on the woodland floor, often at conspicuous locations, detecting hibernacula without the use of radiotelemetry proved labour intensive but possible through systematic searches. The fact that hazel dormice lose a relatively high proportion of their body mass during the winter highlights the challenges wild animals face to survive hibernation. [ABSTRACT FROM AUTHOR]

Very high frequency (VHF) radio tracking technology deployed on terrestrial vertebrates has been well utilized in ecology without much evolution since the 1960s. With the advent of multi‐species rewilding projects, and the new field of reintroduction biology, there has been an increase in requirements for telemetry systems to monitor survival and mortality for many animals simultaneously. Common, pulsed VHF can only monitor one individual on each radio frequency, and the number of individuals monitored is constrained by the amount of time spent on each frequency to facilitate a detection and the number of receivers. Coded VHF largely removes these constraints by using a digital code that can simultaneously monitor up to 512 individuals on a single frequency. Incorporated into an autonomous monitoring system, the coded VHF system also greatly reduces time in the field to confirm the status of individuals. Here we demonstrate the utility of coded VHF technologies applied to monitoring a reintroduced population of brush‐tailed bettong (Bettongia penicillata) on the Southern Yorke Peninsula in southern Australia. A system of autonomous monitoring towers was able to monitor 28 different individuals simultaneously without having to change frequency on any of the towers. During a single 24‐h period, one individual was recorded 24,078 times. Key benefits of the high detection rate and autonomous recording are, a timely response to mortalities or a predation event, the detection of nocturnal, cryptic, or burrowing species whenever they are active, and the reduced need for personnel to be in the field. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aims to investigate the behavior and ecology of nutria (Myocastor coypus), a semi-aquatic rodent that was introduced to South Korea for commercial farming and subsequently damaged aquatic ecosystems after its release. How the behavioral ecology of introduced nutria changes over time and across seasons remains unclear. Twenty-four adult nutria (twelve males and twelve females) were radio tracked in 2015–2016 to identify their home range size and activity patterns in the Macdo wetland, South Korea. This study found that the nutria home range size varied seasonally, with males having larger home ranges than females. Additionally, nutria showed crepuscular and nocturnal activity patterns throughout the year, with no significant difference between sexes. The findings of this study provide crucial information on the home range and activity patterns of introduced nutria in the Macdo wetland, which can guide management efforts to mitigate their impacts on the ecosystem. It is the first quantitative analysis of the home range and activity patterns of introduced nutria based on radio tracking data in the Macdo wetland. Nutria (Myocastor coypus) are semi-aquatic rodents that were introduced in South Korea for commercial farming but significantly damaged aquatic ecosystems. Understanding nutria ecological behavior is essential for developing effective control and eradication strategies to mitigate their impacts. Thus, this study aimed to investigate the home range and activity patterns of 24 nutria (12 males and 12 females) in the Macdo wetland in South Korea from 2015–2016 through radio tracking. The average minimum convex polygon home range of the nutria was 0.29 ± 0.55 km2, with a 95% kernel density estimation (KDE) home range of 0.43 ± 0.85 km2 and a 50% KDE home range of 0.05 ± 1.1 km2. The home range of males was larger than that of females; however, the winter home range of females was as large as that of males. The home range also varied seasonally, with the smallest observed in winter. The nutria showed crepuscular and nocturnal activity patterns throughout the year, with no significant difference between sexes. The activities in spring, summer, and autumn showed no significant differences, but the activity in winter was significantly different from that in the other seasons. This study may serve as a basis for developing appropriately timed and scaled management strategies to mitigate the impacts of nutria on ecosystems. In conclusion, several environmental and biological factors contribute to the behavior of nutria in South Korea. [ABSTRACT FROM AUTHOR]

The Short-eared Owl (Asioflammeus) inhabits open grasslands and belongs to the ground-breeding birds that have experienced the most severe declines during recent decades. Here, we studied nest and fledgling survival of the owl species in relation to (i) habitat composition, (ii) vegetation structure, (iii) weather conditions and (iv) vole abundance. The study was conducted on the East Frisian Island of Spiekeroog (southern North Sea, Lower Saxony, Germany), which harbours one of the last remaining permanent populations of the species in Central Europe. With a mean hatching success of 5.6 young per nest (N = 34) and an average probability of nest survival of 0.9 (N = 28), values ascertained in this study exceeded those reported in previous research. We attribute this to the special environmental conditions on the island, i.e. (i) the absence of mammalian mesopredators such as the Red Fox (Vulpesvulpes), (ii) nearly no disturbance through agricultural measures and (iii) low level of human disturbance due to legal regulations of the National Park. By contrast, the survival of fledglings was lower than survival of nests and varied considerably between the investigated years. Weather conditions were the key driver of fledgling survival. Maximum wind speed and sunshine duration had a negative effect on the probability that chicks successfully fledged. Both lead to reduced hunting success, and the former is also associated with increased costs for thermoregulation. Consequently, increasing frequency of extreme weather events caused by climate change could negatively impact the breeding success of vole-dependent raptors, such as the Short-eared Owl. [ABSTRACT FROM AUTHOR]

Semipalmated sandpipers are Arctic breeding shorebirds that migrate to South America during the non‐breeding season. Little work has been done to understand the daily movements, foraging habits and metabolic state of this species on stationary nonbreeding grounds. Our work was conducted at the Banco dos Cajuais Western Hemisphere Shorebird Reserve Network (WHSRN) site in Northeast Brazil. We captured semipalmated sandpipers in February and March 2019 and 2020 and attached nanotags to monitor their daily movements. Blood samples were taken to measure plasma triglycerides (an index of fattening rate). We also conducted behavioral observations on foraging birds. Using tracking data we determined that most semipalmated sandpipers appeared to use sunrise/sunset as an indicator for movement between salina and tidal flat habitats, and a smaller portion used tidal height. We found birds spent similar amounts of time foraging on tidal flats and in salinas, though different foraging modes were used. Plasma triglyceride measures suggest semipalmated sandpipers had not started preparing to migrate when sampled. We successfully tracked semipalmated sandpipers to North America during northward migration in 2020, detecting eight within the United States. Tracking results suggest many stopped elsewhere in South America to fuel for migration, though some may have fueled at the Banco dos Cajuais. By demonstrating substantial use of both natural and altered habitats in the region by migrant semipalmated sandpipers, these data highlight the need for broader conservation measures throughout coastal regions of South America. [ABSTRACT FROM AUTHOR]

Radio Doppler measurements between the InSight lander and NASA's Deep Space Network have been acquired for measuring the rotation of Mars. Unlike previous landers used for this purpose that utilized steerable high-gain antennas, InSight uses two fixed medium-gain antennas, which results in a lower radio signal-to-noise ratio (SNR). Lower SNR results in additional thermal noise for Doppler measurements using standard processes. Through a combination of phase averaging and traditional data compression, the increased thermal noise due to low SNR can be removed for most of the signal of interest, resulting in more accurate Doppler measurements. During the first 900 days of InSight operations, Doppler measurements were improved by ~25% on average using this method. [ABSTRACT FROM AUTHOR]

In the context of conservation science and management, the Judas technique refers to outfitting an animal (a Judas animal) with a radio transmitter or other identifier so that its movements can be tracked to locate conspecifics. Although this term is commonly used, some consider it offensive due to historical associations of the word Judas with anti‐Semitic sentiments. Thus, the term has a negative sentiment polarity (i.e., the assertion that words can have positive, negative, or neutral connotations). We investigated the etymology of the Judas term in peer‐reviewed scientific literature to outline its contextual introduction and use. Prior to the term being co‐opted by conservation scientists Judas [animal] was a common term in the livestock industry to describe animals used to lead herds to slaughter. Subsequently, the term has been published and promulgated through conservation‐related research and the literature. Due to a negative sentiment polarity linked to this term, especially among members of the public, alternative nomenclature may be preferred to increase objective and dispassionate scientific communication. [ABSTRACT FROM AUTHOR]

In migratory birds, constraints due to breeding are relaxed during the non-breeding season and thus, social behaviours and spatial associations are potentially more directly coupled to food resources and habitats. Use of space and territorial behaviour has rarely been studied in Afro-Palearctic migrants. Variation in strategies could exist among species within the same habitat because of differences in foraging, diet and microhabitat. We compare use of space and association with conspecifics in Common Chiffchaffs Phylloscopus collybita and Subalpine Warblers Sylvia cantillans at a non-breeding site in northern Senegal using radio telemetry and playback experiments. Home ranges of Chiffchaffs were larger and overlapped more than those of Subalpine Warblers. Though Chiffchaffs were often close together, we found no signs of spatial association among individuals in either species. Chiffchaffs showed no clear pattern of territorial response to conspecific song; whereas, playback elicited a territorial response in most Subalpine Warblers. Our results suggest species-specific differences in use of space that might reflect differences in foraging ecology and microhabitat. [ABSTRACT FROM AUTHOR]

A detailed understanding of the spatial ecology and habitat requirements of endangered species is critical for population restoration and conservation. Home ranges and movements of the endangered Chinese softshell turtle (Pelodiscus sinensis) were investigated in the Yellow River, northwestern China, from October 2016 to July 2018. We monitored 9 adult turtles (5 females and 4 males) with radio transmitters. Mean linear range size was 440 ± 161 m SD, mean river channel area was 1.98 ± 0.72 ha SD, the average minimum convex polygon was 1.36 ± 0.65 ha SD, average 95% kernel density estimator measured 0.84 ± 0.51 ha SD, with a core area (50% kernel density estimator) of 0.30 ± 0.20 ha SD. Home range values were not significantly different between the sexes nor were they related to straight-line carapace length or mass. Daily movements of P. sinensis averaged 35 ± 18 m SD for males and 43 ± 18 m SD for females, and there was no significant difference between sexes or significant correlation between movement patterns and body size. However, during the nesting season, there was a significant difference between sexes. Turtle activity was highest in May (average daily movement 59 ± 6 m SD) and lowest in January (0.4 ± 0.6 m SD). Given that P. sinensis individuals have small home ranges and are capable of existing in small rivers, management efforts should protect smaller rivers that may be easily overlooked. Results from this study provide the first assessment of home range requirements for P. sinensis, which may be used in future population modeling efforts and are important for establishing conservation strategies for this vulnerable species. [ABSTRACT FROM AUTHOR]

From 2000 to 2002, the reproductive ecology of the endangered Hainan four eye-spotted turtle (Sacalia insulensis) was studied on Hainan Island, China. A total of 147 adult females were captured, and their reproductive status was evaluated by palpation, X-ray imaging, and ultrasound. Twenty-two gravid females were under observation when they laid their eggs. We observed gravid females and nesting behavior along stream banks between December and April. Nest dimensions ranged from 5 to 6 cm in diameter and from 2 to 3 cm in depth. No females in our study produced more than 1 clutch per season. Clutch size average was 1.9 eggs (range = 1–3 eggs, SD = 0.56, n = 22) with an average egg mass of 16.05 g (range = 11.8–21.0 g, SD = 2.417, n = 21), an average egg width of 2.36 cm (range = 2.1–2.7 cm, SD = 0.135, n = 21), and an average length of 4.65 cm (range = 3.9–5.3 cm, SD = 0.400, n = 21). Hatching success rate was 53%, and hatchlings emerged after an average of 120.9 d (range = 98–148 d, SD = 14.94, n = 21) in late June to early July. The mean nesting site ground temperature was 24.43°C (range = 15.0°C–30.2°C, SD = 2.712, n = 7). [ABSTRACT FROM AUTHOR]

Although radio collars are widely applied in movement ecology, their use in animals with changing neck circumferences is challenging. We are proposing a model of a simple, cheap, and expandable collar that is suitable for the monitoring of young terrestrial mammals. We tested the collar on young crab-eating foxes. There was no register of injuries caused by the collar to the tagged animals, and they functioned appropriately. Thus, we hope this note will encourage further researchers to use our method to monitor the movement patterns of young animals, not only for canids but also for other species of terrestrial mammals. [ABSTRACT FROM AUTHOR]

As part of a project to introduce avian predators for biological pest control, we used hard and soft release methods to introduce Barn Owls (Tyto alba) in the urban area of Universiti Sains Malaysia in Penang, Malaysia. We tested five methods: (1) hard release of non-acclimated adults, (2) hard release of non-acclimated juveniles, (3) soft release of hand-reared fledglings, (4) soft release of acclimated juveniles, and (5) soft release of acclimated adults. We employed radio-tracking to analyze the success of all methods, and the movement and survival of some of the released birds. We analyzed regurgitated pellets to study the diet of the successfully introduced owls. All hard-released non-acclimated adults and non-acclimated juveniles left the study area within a few days after their release. Soft release of hand-reared fledglings was also unsuccessful, as we could only detect the radio-tracked owls for ≤10 d after their release. Of the nine acclimated juveniles that were soft released, one stayed within the study area for 25 d but eventually dispersed. The soft release using acclimated adults was the most successful release method, as 60% (3 of 5 birds) of the released owls were tracked for >30 d and became established as resident birds in the study area. We observed these adults roosting and hunting prey within the study area. Analysis of regurgitated pellets showed the resident Barn Owls preyed primarily on small mammals. Our results suggest that the most suitable method to introduce and establish Barn Owl populations in an urban area was by using soft release of acclimated adults. [ABSTRACT FROM AUTHOR]

Amphibians are among the most threatened vertebrate taxa due to anthropogenic habitat change and emerging pathogens. The fungus Batrachochytrium dendrobatidis (Bd) may cause trade‐offs between the immune responses and other important functions, such as mobility. The pool frog (Pelophylax lessonae) is red‐listed in Sweden, and an earlier study conducted in our study area did not detect the fungus. In this study, 67 Swedish pool frogs were tested for Bd. Of these, 28 adults were provided with external radio transmitters and tracked during the summer and autumn to compare movement among infected and non‐infected individuals. Additionally, we tested some individuals for Bd twice during the summer to study intra‐seasonal variation in individual infections. Our results suggest that Bd has recently invaded these pool frog populations. During autumn, movement distances of infected pool frogs were shorter compared to uninfected individuals, and summer movements within ponds were reduced by increasing Bd load. We also found that the frogs can clear (or reduce) Bd infection during their active season. The results from this study increase understanding of the implications of Bd infections in an anuran fringe population, as well as in amphibian metapopulations, and can further guide amphibian conservation planning and management. [ABSTRACT FROM AUTHOR]

African tigerfish Hydrocynus vittatus (n = 35) were tagged with external radio‐transmitters in the Kavango River, Namibia, to determine whether freshwater protected areas could be an effective tool for the management and conservation of this species. They were manually tracked in the core study area of 33 km every c. 12 days from July–October 2016 to May 2017 for between 123 to 246 days. In addition, 14 extended surveys were carried out for up to 680 km to determine the total area use of the tagged individuals. Tigerfish displayed at least two behavioural patterns either having high site fidelity with shorter movements or using larger areas with longer movements. Twenty‐three (66%) of the tigerfish had high site fidelity using an area of less than 33 km of river, whereas 12 tigerfish (34%) undertook long distance movements of up to 397 km upstream and 116 km downstream from their tagging locations. During the long‐distance movements tigerfish crossed the territorial boundaries of Angola, Namibia and Botswana. Of the 35 fish that were monitored, 14 (40%) spent more than 80% of the monitored time in the 33 km study area and 18 (51%) stayed within the study area for at least 50% of the monitored time. These findings suggest that freshwater protected areas may be a useful management tool and we predict that a protected river area of 2–5 km river length could protect 25.9–34.6% of the population for at least 75% of the time whereas protection of 10 km river length could protect at least 50% of tigerfish for at least 75% of the time. [ABSTRACT FROM AUTHOR]

Mammalian space‐use patterns are largely determined by the resources utilized as well as by given habitat characteristics, as can be illustrated by rodents displaying predominantly subterranean activity. These rodents are largely limited in their use of space by their burrow systems. This results in smaller home ranges than is usual for rodents of a similar size. However, there is little information regarding how stable these home ranges are over time. We studied space use in the giant root‐rat, Tachyoryctes macrocephalus, a large fossorial rodent endemic to the Bale Mountains of southern Ethiopia where it is the principal prey of the Ethiopian wolf Canis simensis. We radio‐tracked 22 root‐rats during a period of 36 days in the early dry season and 17 of them once again during a period of 37 days in the late dry season. The root‐rats occupied very small (around 100 m2) home ranges which were often tightly packed, especially on a wetland shore that was a part of the study locality, but displayed little overlap. Almost 30% of the radio‐collared root‐rats of either sex dispersed (80–428 m from their original home range) during the 5 months of the study, mostly in a period between the early and late dry season characterized by a decreasing food supply and the soil becoming dry and hard. Individuals who did not disperse during this time usually shifted their home range. Root‐rats living on the wetland shore, which were the largest and therefore likely competitively strongest individuals, shifted their home ranges into the wetland, likely for the purpose of increasing their food supply. [ABSTRACT FROM AUTHOR]

At present, tracking data for planetary missions largely consists of radio observables: range-rate (Doppler), range and angular position (VLBI/ Δ DOR). Future planetary missions may use Interplanetary Laser Ranging (ILR) as a tracking observable. Two-way ILR will provide range data that are about 2 orders of magnitude more accurate than radio-based range data. ILR does not produce Doppler data, however. In this article, we compare the relative strength of radio Doppler and laser range data for the retrieval of parameters of interest in planetary missions, to clarify and quantify the science case of ILR, with a focus on geodetic observables. We first provide an overview of the near-term attainable quality of ILR, in terms of both the realization of the observable and the models used to process the measurements. Subsequently, we analyse the sensitivity of radio Doppler and laser range measurements in representative mission scenarios for parameters of interest. We use both an analytical approximation and numerical analyses of the relative sensitivity of ILR and radio Doppler observables for more general cases. We show that mm-precise range normal points are feasible for ILR, but mm-level accuracy and stability in the full analysis chain are unlikely to be attained, due to a combination of instrumental and model errors. We find that ILR has the potential for superior performance in observing signatures in the data with a characteristic period of greater than 0.33–1.65 hours (assuming 2–10 mm uncertainty for range and 10 μ m/s at 60 s for Doppler). This indicates that Doppler tracking will typically remain the method of choice for gravity field determination and spacecraft orbit determination in planetary missions. ILR data will be able to supplement the orbiter tracking data used for the estimation of parameters with a once-per-orbit signal. Laser ranging data, however, are shown to have a significant advantage for the retrieval of rotational and tidal characteristics from landers. Similarly, laser ranging data will be superior for the construction of planetary ephemerides and the improvement of solar system tests of gravitation, both for orbiter and for lander missions. [ABSTRACT FROM AUTHOR]

We used externally applied transmitters to study movements of female grass snakes (Natrix natrix) during the egg-laying period in a near-urban landscape in Sweden. Half of the studied snakes were residents while the other half were translocated individuals with no previous experience of the area. As predicted, resident females moved more goal-oriented and shorter distances than did translocated individuals. Habitat use did not differ between resident and translocated snakes; they were typically found in bushes, reeds, and tall vegetation. Habitat preference (use in relation to availability) showed that bushy habitats, tall grassy vegetation and reedbeds were over-used in proportion to availability, whereas forest and open grass lawns were used less than expected based on availability. Our study highlights the importance of preserving and restoring linear habitat components providing shelter and connectivity in conservation of grass snakes. We suggest that externally applied transmitters are a better option than surgically implanted ones in movement studies of grass snakes, and that translocation as a conservation method for snakes has drawbacks. [ABSTRACT FROM AUTHOR]

Adult Podocnemis unifilis were monitored using VHF radio tracking from September 2013 to September 2014 in the Rio Trombetas Biological Reserve, Pará, Brazil. Our aim was to analyze the use of space by this species near the nesting beach base by describing size and overlap of estimated home ranges. Transmitters were attached to 10 males and 10 females. The mean home range size calculated through the fixed-kernel (FK) method with 95% of the fixes was 79.28 ± 77.08 ha (0.56–215.07 ha; n = 13). The mean of overlapping areas was 14% with FK95% (0.02%–81%; n = 13) and 5% with FK50% (0.1%–23%; n = 9). There was a significant difference in the mean overlapping areas between females and males. The analysis of the overlap of activity centers estimated by FK50% is extremely important for the establishment of conservation strategies in the management plan for this species in the reserve. We were able to identify 2 critical areas for the maintenance of this population where there was a frequent overlap of activity centers: the first, identified during the dry season, was composed of small overlaps among 7 turtles and was near the nesting areas on the clay banks within the Lago Jacaré; the second, identified during the rainy season, was composed of a concentration of overlap areas of larger size among 6 turtles and was an open area in the flooded forest. It is important not only to protect the nesting areas during the dry season but also to protect flooded forest areas with the major intensity of use along with the canals that link the flooded forests to the lakes in the rainy season. For conservation purposes, it is necessary to continue the protection of the nesting beaches throughout the savannas inside the lake where the species nests in the dry season. The flooded forest areas that are zones of intense use during the rainy season, and the canals where the turtles can move between lakes must be protected throughout the year. [ABSTRACT FROM AUTHOR]

Aim: To investigate the ecological relationship between breeding and wintering in specialist and generalist long‐distance migratory species, and the links between densities and range sizes. Location: Denmark, Senegal and Ghana. Methods: We use radio tracking to study spatial behavior and habitat use in three morphologically and ecologically similar and closely related Phylloscopus species on their widely separated breeding and wintering distributions. During wintering and breeding, willow warblers P. trochilus (winter: n = 9, breeding: n = 13), chiffchaffs P. collybita (n = 11, n = 7), and wood warblers P. sibilatrix (n = 17, n = 14) were tracked. Results: Willow warblers P. trochilus increased home range sizes in winter, whereas it was similar in chiffchaffs P. collybita and wood warblers P. sibilatrix, in both seasons. Home ranges overlapped more in winter than in the breeding season. In winter, home range overlap was similar among species but larger overlap during breeding was indicated for willow warblers. Tree cover was unrelated to home range size but significantly higher in breeding than in winter in all species. However, whereas willow warblers and wood warblers maintained some degree of tall tree cover inside their home ranges in winter, chiffchaffs changed from more than 80% to <1% tree cover, indicating a niche shift. Main conclusions: Individuals of all three species showed changes between breeding and wintering areas in spatial behavior and habitat availability, with larger overlap in winter. The differences in patterns were potentially related to being generalist (willow warbler) or specialist (chiffchaff and wood warbler). These ecological relationships are important for the conservation of migrants and for understanding the link between breeding and wintering distributions and ecology. [ABSTRACT FROM AUTHOR]

Geodetic analysis of radio tracking measurements of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging spacecraft while in orbit about Mercury has yielded new estimates for the planet's gravity field, tidal Love number, and pole coordinates. The derived right ascension (α = 281.0082° ± 0.0009°; all uncertainties are 3 standard deviations) and declination (δ = 61.4164° ± 0.0003°) of the spin pole place Mercury in the Cassini state. Confirmation of the equilibrium state with an estimated mean (whole planet) obliquity ϵ of 1.968 ± 0.027 arcmin enables the confident determination of the planet's normalized polar moment of inertia (0.333 ± 0.005), which indicates a high degree of internal differentiation. Internal structure models generated by a Markov Chain Monte Carlo process and consistent with the geodetic constraints possess a solid inner core with a radius (ric) between 0.3 and 0.7 that of the outer core (roc). Key Points: New solution for Mercury's gravity field provides crucial information on the planet's tidal response and orientationNew determination of Mercury's pole position fully satisfies the equilibrium Cassini stateNew estimate of Mercury's polar moment of inertia supports the presence of a large solid inner core [ABSTRACT FROM AUTHOR]

Increasingly high bandwidths are desired in modern navigation and autonomous RF ranging signal design to achieve better pseudo-noise (PN) ranging accuracy. However, fulfilling the Nyquist criterion for such high-bandwidth signals would be a challenging issue for system design. Considering that the Nyquist criterion is not a necessary condition for PN code tracking, sub-Nyquist sampling can be adopted as a feasible solution to this issue. Nevertheless, it is at the expense of an increase in thermal noise caused by tracking error. This problem is particularly prominent for tracking weak signals such as navigation signals, which limits the applicability of this sampling scenario. As far as high-precision autonomous PN ranging is concerned, however, the tracking error due to digital implementation is not negligible and even becomes the dominating factor instead of thermal noise. This means that the performance loss incurred by sub-Nyquist sampling can be eliminated under high-signal-to-noise ratio conditions. Exploiting this fact, this Letter proposes a novel PN code tracking approach based on sub-Nyquist and non-commensurate sampling, providing a solution to achieving high-ranging accuracy while breaking the bounds of the Nyquist sampling theorem without performance degradation. The approach is very attractive for precise PN ranging applications demanding miniaturised implementation. [ABSTRACT FROM AUTHOR]

Understanding the habitat requirements of threatened species is essential for developing effective conservation and habitat management plans. The Siamese fireback (Lophura diardi), a lowland pheasant species found in mainland Southeast Asia, has mostly been studied in its areas of range expansion in submontane forests. However, there is limited information on the species' ranging behaviour and habitat use in their lowland habitat. We investigated the ranging behaviour, patterns of habitat use, and roost site selection using radio telemetry in a small and well-protected lowland forest in northeastern Thailand. The home range size was slightly larger during the non-breeding season (26.4 ± 3.9 SE ha) than during the breeding season (20.8 ± 2.3 SE ha). The birds selected areas with high tree density at 3-5 m height, sparse tree coverage at 0.5-3 m height and high climber density in proximity to water sources. In addition, the Siamese fireback appeared to prefer roost sites on steeper slopes with less canopy cover, presumably to facilitate escape by flushing during attempted predation. Our results provide the first ranging ecology information on lowland Lophura species in their typical habitat which can be used as the basis for further research of other cryptic Lophura species in Southeast Asia. [ABSTRACT FROM AUTHOR]

Zamenis scalaris is a generalist active forager Mediterranean snake for which knowledge on spatial ecology is very limited. We report insights into the spatial and temporal patterns, and habitat use of four snakes, obtained through one-year radio-tracking monitoring in a citrus orchard landscape, in Eastern Iberia. Snakes showed a highly secretive behaviour, remaining hidden most of the annual cycle (>96% of records). Annual home ranges and movements were reduced in contrast to the expected energetic requirements of the species. Despite a similar pattern of non-activity during winter and a subsequent increase of movement rate and home range size in spring, each snake adopted a distinct spatial behaviour in summer and autumn. Abandoned citrus orchards and accessory constructions were the most frequent habitats selected by snakes, offering abundant prey and shelter. These resources are likely playing a crucial role in the spatial ecology of Z. scalaris. [ABSTRACT FROM AUTHOR]

Abstract The Lunar Reconnaissance Orbiter (LRO) has been orbiting the Moon since 2009, obtaining unique and foundational datasets important to understanding the evolution of the Moon and the Solar System. The high-resolution data acquired by LRO benefit from precise orbit determination (OD), limiting the need for geolocation and co-registration tasks. The initial position knowledge requirement (50 m) was met with radio tracking from ground stations, after combination with LOLA altimetric crossovers. LRO-specific gravity field solutions were determined and allowed radio-only OD to perform at the level of 20 m, although secular inclination changes required frequent updates. The high-accuracy gravity fields from GRAIL, with <10 km spatial resolution, further improved the radio-only orbit reconstruction quality (<10 m). However, orbit reconstruction is in part limited by the 0.3–0.5 mm/s measurement noise level in S-band tracking. One-way tracking through Laser Ranging can supplement the tracking available for OD with 28-Hz ranges with 20-cm single-shot precision, but is available only on the nearside (the lunar hemisphere facing the Earth due to tidal locking). Here, we report on the status of the OD effort since the beginning of the mission, a period spanning more than seven years. We describe modeling improvements and the use of new measurements. In particular, the LOLA altimetric data give accurate, uniform, and independent information about LRO's orbit, with a different sensitivity and geometry which includes coverage over the lunar farside and is not tied to ground-based assets. With SLDEM2015 (a combination of the LOLA topographic profiles and the Kaguya Terrain Camera stereo images), another use of altimetry is possible for OD. We extend the 'direct altimetry' technique developed for the ICESat mission to perform OD and adjust spacecraft position to minimize discrepancies between LOLA tracks and SLDEM2015. Comparisons with the radio-only orbits are used to evaluate this new tracking type, of interest for the OD of future lunar orbiters carrying a laser altimeter. LROC NAC images also provide independent accuracy estimation, through the repeated views taken of anthropogenic features for instance. Highlights • The LRO trajectory was reconstructed from July 2009 to November 2016. • GRAIL gravity and radio tracking result in typical overlap performance of 50 cm radially and <10 m in total position. • We use altimetric ranges as geodetic tracking data directly against global, high-resolution LOLA basemaps. • Altimetry alone supports orbit reconstruction better than 20 m in total position, of interest for future lunar exploration. [ABSTRACT FROM AUTHOR]

Leopard ( Panthera pardus ) populations are declining worldwide. There are limited data on leopard ecology, especially activity patterns and habitat use, but these are vital to facilitate their conservation. In Zambia we radio tracked two female and three male leopards to study home range sizes, activity patterns and habitat preferences in Luambe National Park (LNP), and an adjacent Game Management Area used for trophy hunting. Home range sizes (MCP 95%) comprised 28.3–55.7 km 2 for males and 3.1–42.3 km 2 for females; Kernel densities (50%; 95%) were 32.5–80.6 km 2 for males and 3.0–23.0 km 2 for females. The home range for one female shrank during motherhood. Analysis of habitat use and activity patterns of leopards revealed sex-specific differences. Males showed a higher mobility than females. During 24-h observations all individuals showed a minimum mobility during noon hours and maximum mobility before sunrise and sunset. Analyses of habitat preferences using the Jacob-Index and R package adehabitatHS showed that leopards prefer denser vegetation types and rather avoid grassland. These findings should be taken into account in conservation decisions, for example in the granting of trophy hunting activities. [ABSTRACT FROM AUTHOR]

Abstract: In social insects, the activity rhythm of foragers and their action range determinate the activity of the colony. In vespids, which are mostly predators, the foraging range of workers determines their maximum predation pressure round the nest. One of these species, Vespa velutina, a recently invasive species introduced into Europe, exerts a strong predation on honeybees at the hive. Therefore, the definition of its activity rhythm and spatial range of predation is of primary importance. Using radio frequency identification tags (RFID), two experiments were carried out to (a) determine their return ability (called homing) in releasing 318 individuals at different distance from their colony and (b) monitor their foraging activity rhythm and the duration of their flights based on 71 individuals followed 24 hr/24 during 2 months. The homing ability of V. velutina was evaluated to be up to 5,000 m and was not affected by the cardinal orientation of release point. The lag time to return to the nest increased with the distance of release. Most of the flight activity took place between 07:00 a.m. and 08:00 p.m., hornets doing principally short flights of less than an hour. Foraging range was thus estimated ca. 1,000 m around the nest. This study of V. velutina assisted by RFID tags provides for the first time a baseline for its potential foraging distance that increase our knowledge of this species to (a) refine more accurately models for risk assessment and (b) define security perimeter for early detection of predation on invasion front. [ABSTRACT FROM AUTHOR]

Repeated use of the same areas may benefit animals as they exploit familiar sites, leading to consistent home ranges over time that can span generations. Changing risk landscapes may reduce benefits associated with home range fidelity, however, and philopatric animals may alter movement in response to new pressures. Despite the importance of range changes to ecological and evolutionary processes, little tracking data have been collected over the long-term nor has range change been recorded in response to human pressures across generations. Here, we investigate the relationships between ecological, demographic and human variables and elephant ranging behaviour across generations using 16 years of tracking data from nine distinct female social groups in a population of elephants in northern Kenya that was heavily affected by ivory poaching during the latter half of the study. Nearly all groups--including those that did not experience loss of mature adults--exhibited a shift north over time, apparently in response to increased poaching in the southern extent of the study area. However, loss of mature adults appeared to be the primary indicator of range shifts and expansions, as generational turnover was a significant predictor of range size increases and range centroid shifts. Range expansions and northward shifts were associated with higher primary productivity and lower poached carcass densities, while westward shifts exhibited a trend to areas with higher values of primary productivity and higher poached carcass densities relative to former ranges. Together these results suggest a trade-off between resource access, mobility and safety. We discuss the relevance of these results to elephant conservation efforts and directions meriting further exploration in this disrupted society of a keystone species. [ABSTRACT FROM AUTHOR]

Five specimens (2 ♀, 3 ♂) of the gecko species Rhacodactylus leachianus were radio-tracked for 14 days on Île de Bayonnaise, New Caledonia. Using thermo-sensitive transmitters, specimens were mapped continuously every hour. All movements, behavioural expressions and core temperatures were manually recorded, while data loggers simultaneously recorded the temperatures of microhabitat structures. In an additional trial, all geckos captured on the island were marked with Passive Integrated Transponders (PITs): Twenty-two adults (13 ♀, 9 ♂) and one subadult were marked in total. The mapping of R. leachianus on this island was repeated during 2005, 2007 and 2013. Average core temperatures of 23.4°C (♀) and 24.1°C (♂) were recorded ranging of 18.2-32.0°C (♀) and 18.0-32.2°C (♂), respectively. No sex-dependent differences were noted, but a clear relation to the local air temperature was found. Gravid females showed higher core temperatures (by up to 3°C) during oviposition. The test for equality of variances showed differences between the core temperatures of both sexes and the air temperature, indicating the ability of both sexes for active thermoregulation. Although no strict territorial borders were noted, males were observed marking their territories vocally. The females showed no territorial behaviour. Home ranges varied between 551 and 3,464 m² for all specimens. Areas within which the geckos were active averaged around 5 m per night, with some rare instances of movements over up to 200 m in one night. We observed that females often left their preferred home ranges for nesting, usually laying their eggs in coastal dunes. We presume that this occurred in search of higher, more stable soil temperatures. [ABSTRACT FROM AUTHOR]

Drifting macrophytes such as seagrass and macroalgae are commonly found washed ashore on sandy beaches but few studies have investigated the drift trajectories of macrophytes whilst near to the coast. This is the first study to investigate the surface drifting of small clumps of seagrass released at various distances from shore, across multiple days with contrasting wind and tidal conditions, in a large gulf in southern Australia. Natural and artificial radio-tagged seagrass units generally travelled in the same directions as tides but trajectories were variable across sampling days and when tagged units were released at different distances from shore. Natural and artificial units diverged from each other particularly on days when wind speeds increased but generally drifted in the same direction and ended up within close proximity to each other at the 6-h endpoint. During calm conditions, tagged seagrass units drifted with tides for 0.25–5 km and, during one sampling day when wind speeds increased, drifted for >5 km over the 6-h time period. Only tagged units that were released closest to shore stranded on sandy beaches within the six hours of observation, so it would be difficult to predict the eventual stranding location on shorelines for macrophytes released further offshore. This study provides evidence of the variability of macrophyte drift dynamics near to coastlines. Acknowledging this variability is essential for further understanding of the ecological significance of allochthonous material arriving at shorelines, which should be integrated into future research and management of sandy-beach ecosystems. [ABSTRACT FROM AUTHOR]

The feeding and drinking behaviours of sheep were monitored using RFID technology at a commercial pre-embarkation feedlot in Western Australia with the aim of characterizing feeding and drinking patterns of inappetent sheep that might allow them to be treated. Feeding and drinking behaviours of sheep were compared with their survival and change in body condition. Patterns of number of visits and the time spent at feed and water troughs were analyzed for a total of 8,206 sheep, representing four consignments that were monitored for a range of 6-31 d. Data for feeding and drinking behaviours were compared for the first 6 d. For animals that were alive at exit, 18.9% of sheep attended the feed trough for less than 0.25 h d-1 (15 min per day) on day 1; this decreased to only 2.4% of sheep by day 6. Of the sheep monitored, 0.93% died (n = 76); Salmonella spp. infection was the leading cause of death (n = 40; 52.6% of all deaths) across all months and was accompanied with inanition. There was marked variability in the average time spent at the feed trough for sheep that died eventually from salmonella/inanition (contributing to the lack of statistical difference in time spent at feed trough between sheep dying from different causes; P = 0.056). Over half (55%) of the animals diagnosed with salmonella/inanition spent an average of less than 0.50 h d-1 (30 min per day) and 45% less than 0.25 h d-1 at the feed trough. There was a negative correlation (r) in time spent at the feed trough overtime for individual sheep that died from salmonella/inanition, indicating that these individuals went off their feed. This pattern was not evident for animals that died from other causes (significant difference in r values between five categories of cause of death; P = 0.040). Characterization of feeding behaviour of sheep that died from salmonella/inanition therefore appears to require more than simply monitoring daily intake. There was no difference in time spent at water troughs between sheep that died or were alive at exit (average 0.30 ± 0.23 h d-1). This study reveals that the patterns of feeding and drinking behaviours during pre-embarkation feedlotting do not readily allow identification of animals that warrant singling out for veterinary care or alternative feed arrangements. This result highlights the need for experienced stockmanship in handling these animals. [ABSTRACT FROM AUTHOR]

Accurate tracking of probes is one of the key points of space exploration. Range and Doppler techniques are the most commonly used. In this paper we analyze the impact of the transponder delay, i . e . the processing time between reception and re-emission of a two-way tracking link at the satellite, on tracking observables and on spacecraft orbits. We show that this term, only partially accounted for in the standard formulation of computed space observables, can actually be relevant for future missions with high nominal tracking accuracies or for the re-processing of old missions. We present several applications of our formulation to Earth flybys, the NASA GRAIL and the ESA BepiColombo missions. [ABSTRACT FROM AUTHOR]

Since Rosetta's lander Philae touched down on comet 67P/Churyumov-Gerasimenko on November 12, 2014, many tools have been applied to reconstruct Philae's flight path and attitude between separation, the touchdowns, collision and the final landing at Abydos. In addition to images from the cameras onboard both orbiter and lander (“OSIRIS”, “CIVA” and “ROLIS”), radio tracking results, solar array and radio data link housekeeping data, one of the major sources for timing and attitude information were two point magnetic field measurements by the magnetometers “ROMAP” and “RPC-MAG” aboard Philae and Rosetta. In this study all the different results are combined to determine in further detail what happened to Philae during its travel above the surface of 67P/Churyumov-Gerasimenko. In addition to a description of the descent dynamics and the attitude during rebound, the approximate coordinates for the collision at 16:20 UTC with the rim of the Hatmehit crater and the second touchdown are estimated. It is also shown, that Philae did not change attitude between the end of the first-science sequence and September 2, 2016. [ABSTRACT FROM AUTHOR]

Quantifying and managing the potential adverse wildlife impacts of offshore wind energy is critical for developing offshore wind energy in a sustainable and timely manner, but poses a significant challenge, particularly for small marine birds that are difficult to monitor. We developed a discrete-time Markov model of seabird movement around a colony site parameterized by automated radio telemetry data from common terns ( Sterna hirundo ) and Arctic terns ( S. paradisaea ), and derived impact functions that estimate the probability of collision fatality as a function of the distance and bearing of wind turbines from a colony. Our purpose was to develop and demonstrate a new, flexible tool that can be used for specific management and wind-energy planning applications when adequate data are available, rather than inform wind-energy development at this site. We demonstrate how the tool can be used 1) in marine spatial planning exercises to quantitatively identify setback distances under development scenarios given a risk threshold, 2) to examine the ecological and technical trade-offs of development alternatives to facilitate negotiation between objectives, and 3) in the U.S. National Environmental Policy Act (NEPA) process to estimate collision fatality under alternative scenarios. We discuss model limitations and data needs, and highlight opportunities for future model extension and development. We present a highly flexible tool for wind energy planning that can be easily extended to other central place foragers and data sources, and can be updated and improved as new monitoring data arises. [ABSTRACT FROM AUTHOR]

Scatter-hoarding animals such as corvids play a crucial role in the dispersal of nut-producing tree species. This interaction is well known for some corvids, but remains elusive for other species such as the magpie ( Pica pica), an abundant corvid in agroecosystems and open landscapes of the Palearctic region. In addition, the establishment of the individual dispersed seeds-a prerequisite for determining seed-dispersal effectiveness-has never before been documented for the interaction between corvids and nut-producing trees. We analyzed walnut dispersal by magpies in an agroecosystem in southern Spain. We used several complementary approaches, including video recording nut removal from feeders, measuring dispersal distance using radio tracking (with radio transmitters placed inside nuts), and monitoring the fate of dispersed nuts to the time of seedling emergence. Magpies were shown to be highly active nut dispersers. The dispersal distance averaged 39.6 ± 4.5 m and ranged from 4.1 to 158.5 m. Some 90% of the removed walnuts were cached later, and most of these (98%) were buried in the soil or hidden under plant material. By the time of seedling emergence, ca. 33% of nuts remained at the caching location. Finally, 12% of the cached nuts germinated and 4% yielded an emerged seedling, facilitating the transition to the next regeneration stage. The results demonstrate for the first time that magpies can be an effective scatter-hoarding disperser of a nut-producing tree species, suggesting that this bird species may play a key role in the regeneration and expansion of broadleaf forests in Eurasia. [ABSTRACT FROM AUTHOR]

Distance of large wood transport during floods and conditions for wood deposition in wide mountain rivers are still insufficiently understood. Tracking of logs tagged with radio transmitters was used to investigate differences in depositional conditions and the length of log displacement during a 20-year flood between channel reaches of different morphology in the Czarny Dunajec River, Polish Carpathians. During the rising limb of the flood, logs were placed into the river at three locations: at the beginning of an incised reach, close to the beginning of a channelized reach, and 1 km upstream from the beginning of a wide, multithread reach. The incised, channelized, and multithread reaches retained 12.5%, 33%, and 94% of tagged logs introduced to these reaches, respectively, and of the logs retained in the multithread reach, all were deposited in its upstream half. Significant differences in the length of displacement existed between the logs delivered to the river at the three locations, with logs placed into the river at the beginning of the incised reach moving the longest distance, and those delivered just upstream from the multithread reach moving the shortest distance before deposition. One-fourth of the logs were deposited in a low-flow channel or on a channel margin, one-fifth on the floodplain, and more than half on gravel bars. After the flood, river cross sections with deposited logs and a set of cross sections without any wood deposits were surveyed to collect data for one-dimensional modelling of hydraulic conditions at the flood peak. The cross sections with deposited logs were typified by significantly greater flow width and flow area and by significantly smaller mean flow depth, mean velocity, Froude number, mean bed shear stress, and unit stream power. Principal component analysis of the hydraulic parameters in the analysed cross sections grouped the two types of cross sections in distinct clusters, indicating that multithread cross sections differed in hydraulic parameters from all the other cross sections. The experiment confirmed findings from the previous wood inventory and numerical modelling of wood transport and deposition in the river, indicating that in a wide mountain river wood can be transported long distances in a narrow, single-thread channel. It is, however, preferentially deposited in a wide, multithread channel that functions as a natural wood trap preventing or considerably limiting further transfer of large wood to vulnerable sites. Therefore, it is crucial to avoid channelization of multithread reaches that would eliminate their functioning as natural wood traps. The hydraulic modelling provided a physical justification for the observed differences in wood behaviour between the distinct channel morphologies. [ABSTRACT FROM AUTHOR]

This paper presents an interplanetary optical navigation algorithm based on two spherical celestial bodies. The remarkable characteristic of the method is that key navigation parameters can be estimated depending entirely on known sizes and ephemerides of two celestial bodies, especially positioning is realized through a single image and does not rely on traditional terrestrial radio tracking any more. Actual Earth–Moon group photos captured by China’s Chang’e-5T1 probe were used to verify the effectiveness of the algorithm. From 430,000 km away from the Earth, the camera pointing accuracy reaches 0.01° (one sigma) and the inertial positioning error is less than 200 km, respectively; meanwhile, the cost of the ground control and human resources are greatly reduced. The algorithm is flexible, easy to implement, and can provide reference to interplanetary autonomous navigation in the solar system. [ABSTRACT FROM AUTHOR]

Radio tracking and astrometric data obtained by the JUICE mission, using the PRIDE, 3GM and JANUS instruments, will allow the dynamics of the Galilean moons to be measured to unprecedented accuracy. As a result, the dynamical models used for creating ephemerides from these data will most likely require the inclusion of various heretofore neglected physical effects. To determine which effects will need to be included, we perform a sensitivity analysis of the influence on the dynamics of the system for a wide array of gravitational, tidal and rotational characteristics of the system. We estimate the dynamics of the Galilean moons with a given perturbation turned off, using ideal three-dimensional measurements of the satellites' positions generated with these perturbations turned on. In doing so, we assess the capabilities of the nominal dynamical model to absorb the influence of this perturbations. We analyze the dynamical behaviour over a period of five years, and limit our analysis to effects that may be observable from JUICE radio tracking and optical astrometry data. Our simulations comprise a short-period (5 years) sensitivity analysis of the dynamics of the moons, and not a simulation of the tracking data inversion for JUICE. Our analysis indicates that the nominal dynamical model of the Galilean satellites can very efficiently absorb the influence of the current uncertainties in most of the physical parameters of the Jovian system, to a level where these uncertainties will not be influential for JUICE-derived ephemerides. An important exception is the influence of tidal dissipation: the k 2 / Q of Io will be clearly observable by JUICE tracking data, which will be strongly correlated with the weaker effect of Jupiter's k 2 / Q . The dissipation inside Europa may also be weakly constrained by JUICE tracking data. Without improvements in the Jovian gravity field from the Juno mission, the estimation of Jupiter zonal gravity field coefficients at degrees 2, 3 and 5 should be included in the ephemerides generation. The influence of the deviation from perfect tidal locking of the moons' rotation is at the limit of observability. Furthermore, we have verified that the present uncertainty in the a priori ephemeris of Jupiter will not influence the (Jupiter-centered) dynamics of the Galilean moons at an observable level. [ABSTRACT FROM AUTHOR]

A population of Eurasian lynx Lynx lynx was established by reintroductions in the Bohemian Forest Ecosystem in the 1970s and 1980s. The most recent information on the population status indicates that the distribution has stagnated since the late 1990s, for unknown reasons. We assessed the availability of suitable habitat along the Austrian–German–Czech border, and hypothesized that the Bohemian–Bavarian lynx population is not in equilibrium with habitat suitability. Based on global positioning system data from 10 radio-collared lynx, we used a maximum entropy approach to model suitable habitat. Variables reflecting anthropogenic influence contributed most to the model and were negatively associated with the occurrence of lynx. We evaluated the model prediction using independent records of lynx from monitoring in Bavaria, Germany. Using our habitat approach we estimated the area of potential habitat, based on a mean annual home range of 445 km2 for males and 122 km2 for females. Our results indicated there were 12,415 km2 of suitable habitat, distributed among 13 patches, for a potential population of c. 142 (93–160) resident lynx. We assessed connectivity via least-cost paths and found that all suitable patches could be reached by the lynx. A comparison with the current distribution of lynx, however, confirms that a significant proportion of suitable habitat is not occupied, which indicates that the distribution is limited by factors other than habitat, with illegal killing being the most likely cause. Our study provides crucial information for the development of a conservation strategy and regional planning for the Bohemian–Bavarian lynx population. [ABSTRACT FROM PUBLISHER]

The Hermann's tortoise is a strictly European species found mostly in areas with Mediterranean and sub-Mediterranean climes and, especially the subspecies T. hermanni hermanni, has to deal with various threats which reduced its geographic distribution to only a few isolated populations. Thus, with the objective of recovering natural populations of the species, numerous reintroduction projects are being carried out throughout its historical and prehistorical geographic distribution. The aim of our study is to evaluate the success of the T. hermanni reintroduction project carried out in the Albufera de Valencia Natural Park since 2011, through the analysis of movements, home range sizes and habitat use in a new environment. The recorded activity pattern presents two peaks, one in spring and another in August, and the hibernation period (from December to February) is the same as observed in other populations. We did not find significant differences in home range sizes between sexes, but a tight relation between home range sizes and body sizes with larger individuals having larger home ranges. This relation was not observed for core areas (Kernel at 50%). Considering the habitat use, we did not find differences between the groups of individuals we defined, but different types of habitats were used differently. "Scrub" was the most frequented (~50%), followed by "dunes" (~20%), "mallaes" (~20%) and "forest" (<20%). Our results can be used to improve the success of future reintroduction projects by directing ideal habitat, timing and carapace size of released Hermann's tortoises. [ABSTRACT FROM AUTHOR]

Behavioural variation within a species is usually explained as the consequence of individual variation in physiology. However, new evidence suggests that the arrow of causality may well be in the reverse direction: behaviours such as diet preferences cause the differences in physiological and morphological traits., Recently, diet preferences were proposed to underlie consistent differences in digestive organ mass and movement patterns (patch residence times) in red knots ( Calidris canutus islandica). Red knots are molluscivorous and migrant shorebirds for which the size of the muscular stomach (gizzard) is critical for the food processing rate., In this study, red knots ( C. c. canutus, n = 46) were caught at Banc d'Arguin, an intertidal flat ecosystem in Mauritania, and released with radio-tags after the measurement of gizzard mass. Using a novel tracking system (time-of-arrival), patch residence times were measured over a period of three weeks. Whether or not gizzard mass determined patch residence times was tested experimentally by offering 12 of the 46 tagged red knots soft diets prior to release; this reduced an individual's gizzard mass by 20-60%. To validate whether the observed range of patch residence times would be expected from individual diet preferences, we simulated patch residence times as a function of diet preferences via a simple departure rule., Consistent with previous empirical studies, patch residence times in the field were positively correlated with gizzard mass. The slope of this correlation, as well as the observed range of patch residence times, was in accordance with the simulated values. The 12 birds with reduced gizzard masses did not decrease patch residence times in response to the reduction in gizzard mass., These findings suggest that diet preferences can indeed cause the observed among-individual variation in gizzard mass and patch residence times. We discuss how early diet experiences can have cascading effects on the individual expression of both behavioural and physiomorphic traits. This emphasizes that to understand the ecological consequences of individual differences, knowledge of the environment during development is required. [ABSTRACT FROM AUTHOR]

A lek is an aggregated male display that females attend for the purpose of fertilization. A male needs to climb the relative hierarchy to be available for mating when the peak of female estrus occurs. We analyzed the link between timing of lek use by males in relation to age, phenotype, territoriality, and mating success. For more than a decade, we collected radio-tracking data and behavioral observations of a lekking mammal, the fallow deer (Dama dama). Competitively stronger males (i.e., older and heavier males with larger antlers) moved to the lek before less competitive ones. However, an early arrival did not guarantee the territory defense for a longer period nor higher mating success. The early arrival seemed to be a necessary but not sufficient condition to be a successful male in a lek. In fact, the ability to defend a territory for longer was related to age, body mass, antler length but not arrival time. We accordingly argue that males move to the lek early because they need to engage in male-male interactions and scent-marking activities. Successful males left the lek later than unsuccessful ones. The latter did not attempt to compensate for their low mating success by remaining in the lek, likely adopting alternative strategies outside of it. Adult males seeking for a chance to defend the territory and mate have to move to the lek early and stay there until the end of the rut, though this does not guarantee them a higher mating success. [ABSTRACT FROM AUTHOR]

The transient stage prior to definitive recruitment, known as juvenile dispersal, is thought to be under great evolutionary pressure and subject to a trade-off between associated costs and long-term benefits for fitness. Conspecific attraction has been shown to be an adaptive mechanism driving dispersal behaviours that may lead to negative density-dependent dispersal patterns. However, conspecific attraction can be scarcely discernible from imprinting to the natal area in wild populations. Reintroductions in the absence of settled individuals can be used as alternative colonization-like contexts to investigate the relative role of conspecific attraction in juvenile dispersal behaviours. We examined the spatiotemporal development of dispersal movements in reintroduced juveniles of a long-lived species with deferred maturity, the Spanish imperial eagle, Aquila adalberti , in comparison with nonmanipulated juveniles from a nearby population. We found that reintroduced birds started dispersal earlier and were initially more philopatric, probably encouraged by the advantageous competitive environment in the release area. Conversely, they revealed a more expansive strategy as they matured and approached the time when settlement decisions would be made, especially in females. They returned less frequently, increased exploratory movements and dispersal ranges, and visited breeding areas, probably as a consequence of the relatively lower reproductive prospects in the release area than in nearby populations. Therefore, the singular social cueing in reintroductions may eventually lead to juvenile wandering behaviours characteristic of colonization contexts in this territorial long-lived species. Such dispersive strategies relying on conspecifics may have important consequences for population dynamics and management. They may hinder the initial settlement phase in reintroductions, although behaviours such as longer returns may enhance recruitment prospects. Translocation programmes should consider specific dispersal scenarios, as well as postrelease monitoring to increase philopatry and success probabilities. [ABSTRACT FROM AUTHOR]

That birds migrate in the reverse direction of the expected is a phenomenon of regular occurrence which has been observed at many sites. Here we use three different methods; tracking radar, radiotelemetry and ringing, to characterize the flights of these reverse migrants and investigate possible causes of reverse migration of nocturnally migrating passerines during autumn migration at Falsterbo peninsula, Sweden. Using these different methods we investigated both internal factors, such as age and fuel load, and external factors such as weather variables, competition and predation risk. Birds flying in the reverse direction were more likely to be lean and to be juveniles. Reverse migration was also more common with overcast skies and winds with north and east components. We did not find any effect of temperature, visibility, number of migrating sparrowhawks, or the total number of ringed birds at the site on the day of departure. We found that reverse migration is characterized by slower flight speeds (airspeed) at high altitudes and that it takes place later in the night than forward migration. [ABSTRACT FROM AUTHOR]