High Capture Probability Research Articles

Capture Mechanism and Optimal Design of Micro-Particle Traps in HVAC/HVDC Gas Insulated Equipment

Gas-insulated equipment such as GIS (Gas-Insulated Substation) and GIL (Gas-Insulated transmission lines) faces critical insulation failure challenges caused by particles inside. However, the particle traps, as key devices available to inhibit the movement of particles, lack theoretical basis and quantitative methodology for trap design especially with high voltage ratings. In this paper, a particle motion excitation and observation platform is established to physically simulate the actual online operating conditions of HVAC/HVDC GIS/GIL and study the capture mechanism of particle traps. Experimental results illustrate that, the collision motion style is a principal factor to affect the particle capturing capability, and the capture behavior of AC and DC particle traps can be classified into three separate modes, depending on variation of the collision process which can be characterized by random probability and the lognormal distribution rebound angle. A particle trajectory simulation model incorporating motion randomness is thereby presented to realize quantitative analysis and further optimize the trap parameters. A hazard index and minimum collision times are defined and calculated to quantitatively evaluate the particle collision effect on trapping capability. Further, a novel trap design topology is proposed to enhance the anti-motion efficiency of the particle traps. Targeted at high objective capture probability, the particle trap parameters are optimized to reduce the hazard index and improve the minimum collision times by the Monte Carlo scheme. The obtained results indicated that, the capture probability of AC traps can reach 86.5% at a gap spacing of 5 mm, while that of DC traps can reach 74.1% with an 8 mm-width slot and a 50-degree inclination angle. Verification of the novel article trap is implemented on a test rig, which gives an increased capture probability by 30% compared with the traditional trap design. The proposed new trap topology and corresponding methodology present quantitative guidance for particle traps optimization and render application potential for different voltage levels.

Aerial Grasping and the Velocity Sufficiency Region

A largely untapped potential for aerial robots is to capture airborne targets in flight. We present an approach in which a simple dynamic model of a quadrotor/target interaction leads to the design of a gripper and associated velocity sufficiency region with a high probability of capture. A model of the interaction dynamics maps the gripper force sufficiency region to an envelope of relative velocities for which capture should be possible without exceeding the capabilities of the quadrotor controller. The approach motivates a gripper design that emphasizes compliance and is passively triggered for a fast response. The resulting gripper is lightweight (23 g) and closes within 12 ms. With this gripper, we demonstrate in-flight experiments that a 550 g drone can capture an 85 g target at various relative velocities between 1 m/s and 2.7 m/s.

Characteristics of anchoveta (Engraulis ringens) schools in the optimum zone and the physiological stress zone of its distribution between 2011 and 2021

AbstractThis study has considered anchoveta acoustic data from the Pelagic Resources Hydroacoustic Assessment Surveys carried out by the Peruvian Sea Institute (IMARPE) and free access satellite data (HYCOM and MODIS from the USA) of some oceanographic variables between the period 2011 and 2021, to know the oceanographic conditions, characteristics of schools and size structure in the optimum zone (OZ) and in the physiological stress zone (PSZ), of their total distribution. The OZ is determined by the extent of the Cold Coastal Waters (CCW), and the PSZ is determined by the mixing of waters, to the north by the CCW‐ESW (Equatorial Surface Waters) and to the west between the CCW‐SSW (Subtropical Surface Waters). The range of sea surface temperature and salinity in the PSZ (16.1–25.0°C and 34.65–35.29, respectively) was wider than in the OZ (14.5–24.0°C and 34.65–35.20, respectively), where a higher number of schools were recorded. Our analyses showed that the morphometric and energetic acoustic descriptors of anchoveta schools in the summer were higher during summers compared to springs. In terms of positional characteristics, the mean depth of the schools in the PSZ was slightly greater than in the OZ. The total size structure of anchoveta in the OZ consisted mainly of juvenile specimens (less than 12 cm total length) in the summer of 2011 and 2013–2014 and in the spring between 2014–2017 and 2021. In the PSZ, adult specimens (greater than 12 cm total length) predominated in summer between 2011–2013, 2015, 2018, and 2021 and in spring between 2011–2013, 2015, and between 2018–2021. However, specimens greater than 10 cm in total length were found in the PSZ. Knowledge of the location of this zone away from the coast will allow a high probability of anchoveta capture of adult specimens during fishing periods.

Spatio-Temporal Distribution of Juvenile Oceanic Whitetip Shark Incidental Catch in the Western Indian Ocean

Oceanic whitetip shark (Carcharhinus longimanus) is an important top predator in pelagic ecosystems currently classified as globally Critically Endangered by the International Union for the Conservation of Nature. This species is incidentally caught by fisheries targeting highly migratory tunas and billfishes throughout the Indian Ocean. Understanding the temporal, spatial and environmental factors influencing the capture of this species is essential to reduce incidental catches. In this study, we used generalized additive models to analyze the spatio-temporal distributions of the juvenile oceanic whitetip shark catches and the environmental conditions in the western Indian Ocean using observer data from 2010 to 2020 of the European Union and associated flags purse seine fishery. We found sea surface temperature and nitrate concentration to be the most important environmental variables predicting the probability of catching an oceanic whitetip shark. A higher probability of capture was predicted in areas where sea surface temperature was below 24°C and with low nitrate concentrations close to zero and intermediate values (1.5-2.5 mmol.m-3). We also found a higher probability of capture in sets on fish aggregating devices than in sets on free schools of tuna. The Kenya and Somalia basin was identified to have higher probabilities of capture during the summer monsoon (June to September) when upwelling of deep cold waters occurs. We provide the first prediction maps of capture probabilities and insights into the environmental preferences of oceanic whitetip shark in the western Indian Ocean. However, the causal mechanisms behind these insights should be explored in future studies before they can be used to design spatial management and conservation strategies, such as time-area closures, for bycatch avoidance.

Interference Cancellation for LoRa Gateways and Impact on Network Capacity

In this paper we propose LoRaSyNc (LoRa receiver with SyNchronization and Cancellation), a second generation LoRa receiver that implements Successive Interference Cancellation (SIC) and time synchronization to improve the performance of LoRa gateways. Indeed, the chirp spread spectrum modulation employed in LoRa experiences very high capture probability, and cancelling the strongest signal in case of collisions can significantly improve the cell capacity. An important feature of LoRaSyNc is the ability to track the frequency and clock drifts between the transmitter and receiver, during the whole demodulation of the interfered frame. Due to the use of low-cost oscillators on end-devices, a signal cancellation scheme cannot result accurate without such a tracking, especially at the lower data rates. We validate the performance of LoRaSyNc in presence of collisions by implementing a receiver prototype on software-defined-radios, and perform several experiments in different realistic scenarios, by also comparing our receiver with commercial gateways. Finally, we simulate a cell deployment with one or more gateways, showing that the proposed scheme improves performance by almost 50% compared to a traditional receiver.

Where and when to hunt? Decomposing predation success of an ambush carnivore.

Predator-prey games emerge when predators and prey dynamically respond to the behavior of one another, driving the outcomes of predator-prey interactions. Predation success is a function of the combined probabilities of encountering and capturing prey, which are influenced by both prey behavior and environmental features. While the relative importance of encounter and capture probabilities have been evaluated in a spatial framework, temporal variation in prey behavior and intrinsic catchability are likely to also affect the distribution of predation events. Using a single-predator-single-prey (puma-vicuña) system, we evaluated which factors predict predation events across both temporal and spatial dimensions of the components of predation by testing the prey-abundance hypothesis (predators select for high encounter probability) and the prey-catchability hypothesis (predators select for high relative capture probability) in time and space. We found that for both temporal and spatial analyses, neither the prey-abundance hypothesis nor the prey-catchability hypothesis alone predicted kill frequency or distribution; puma kill frequency was static throughout the diel cycle and pumas consistently selected a single habitat type when hunting, despite temporal and spatial variation in encounter rates and intrinsic catchability. Our integrated spatiotemporal analysis revealed that an interaction between time of day and habitat influences kill probability, suggesting that trade-offs in the temporal and spatial components of predation drive the probability of predation events. These findings reinforce the importance of examining both the temporal and spatial patterns of the components of predation, rather than unidimensional measures of predator or prey behavior, to comprehensively describe the feedbacks between predator and prey in the predator-prey game.

Does the provision of infrastructural projects attract criminal activities? Chinese aid and Crime in Ghana.

The impacts of Chinese aid in Africa have been the focus of recent studies, suggesting a high probability of elite capture and political patronage. It should make residents in the projects' vicinities feel neglected since the intended benefits that may accrue from the projects are not likely to trickle down to them. The paper examines the impact of Chinese aid projects on criminal activity in Ghana. Using a geo-referenced dataset of sub-national allocation of Chinese projects geographically matched with 8,141 respondents of Afrobarometer surveys for Ghana, we implement a difference-in-difference identification strategy to capture the impact of living near the vicinity of ongoing projects at the time of the survey against those with no projects. The results suggest that living near ongoing projects makes residents prone to be burglarized or physically attacked. There is no equivalent pattern when considering projects financed by other donors.

Influence of Largemouth Bass Behaviors, Angler Behaviors, and Environmental Conditions on Fishing Tournament Capture Success

AbstractTournament anglers typically possess extensive knowledge of the habitat and seasonal movement of their targeted species. While fish–angler behavioral relationships are critical to understanding fish catchability, few studies have assessed how fish behavior influences their vulnerability to capture by tournament anglers. Our objectives were to determine if Largemouth Bass Micropterus salmoides behavior, angler behavior, and environmental conditions affect tournament angler catch rate (CPUE) and Largemouth Bass capture probability at fishing tournaments. Forty‐nine Largemouth Bass were tracked weekly using radiotelemetry during a 4‐month period. Five tournament anglers were also selected at weekly tournament events and tracked continuously using a handheld GPS unit. We quantified individual Largemouth Bass behaviors (home range, weekly movement rate, depth use, and spatial overlap with anglers), angler behaviors (depth use, angler movement rate), and environmental conditions (air and water temperature) and used these estimates as covariates in a multiple regression model to assess their effects on tournament CPUE and then used a multistate mark–recapture model to estimate Largemouth Bass capture probability at tournaments. Our results indicate that Largemouth Bass movement rate, angler fishing depth, and air temperature were highly correlated to tournament angler CPUE. Mark–recapture models also indicated that air temperature and angler–fish overlap were positively associated with Largemouth Bass capture probability while fish total length, home range, movement rate, and depth use were not successful in characterizing individual variation in capture probability. Our results indicate that Largemouth Bass that are encountered by anglers are more likely to be captured, whereas mismatches between angler and Largemouth Bass behavioral factors, including depth use and movement rates, may result in decreased tournament capture rates. Consideration and continued evaluation of the relationships between Largemouth Bass and angler behaviors and environmental variables is critical to fisheries management as tournament pressure paired with high capture probabilities and selective angling can have large‐scale population‐level impacts.

Finding an effective distance between T-cell and B-cell using S/W ARQ in an immune system communication

In this paper, we present the effective distance between T-cell and B-cell in an immune system using Stop and Wait (S/W) Automatic Repeat Request (ARQ). The concentration of the molecules can be increased by increasing the transmitting number of molecules but it may reduce the performance of communication due to higher collision or interference with other molecules. It is also reported in the literature that the concentration of the emitted molecules reduces if the distance from Transmitter (Tx) to Receiver (Rx) increases. Thus, this paper mainly focuses on enhancing the receiver's capture probability and higher successful complete transmission of the desired molecules by obtaining the effective distance from T-cell to B-cell. In order to find the effective distance, T-cell transmits the molecules 1 (Interleukins-2) to B-cell, upon successful reception of molecules 1, antibodies (molecules 2) transmit back to T-cell. Then, the effective distance of an immune system can be obtained after T-cell detects the concentration of the molecules 2 with respect to time. Different schemes of S/W ARQ protocols have implemented in Molecular Communication (MC) but it requires retransmission of duplicate copies due to the lack of addressing an effective distance. Thus, the simulations are performed in MATLAB and the results obtain higher capture probability and also successful complete transmission of the desired molecules.

Fitness of the pestiferous small rodent Mastomys natalensis in an agroecosystem in Mayuge district, Lake Victoria Crescent, Uganda

Abstract A 2.5-year study was conducted to understand the fitness of Mastomys natalensis in an agroecosystem in relationship with environmental predictors. The study was conducted in Mayuge district, in the Lake Victoria Crescent zone in Eastern Uganda. Fitness was measured in terms of survival, maturation and capture probability and estimated using multi-event capture-recapture models. Survival rates were higher after high rainfall in the previous month and increased with increasing population density of the animals. Maturation rate, on the other hand, showed no significant association with any predictor variables, while capture probability was significantly associated with sex of the animals, with higher capture probability for males. The results demonstrate that the fitness of M. natalensis in an agroecosystem is dependent on rainfall, sex and current population density. The aforementioned results were associated with increasing vegetation which provides cover for animal nesting and abundant food for the animals during rainfall periods and thus increased survival, high mobility in males in search for mates thus exposing animals to high chances of being captured and increased prey saturation at high population density resulting in high animal survival. These results have important implications for the timing of management strategies, i.e. control efforts should be enforced during the rainfall seasons to prevent high population buildup in the succeeding seasons.

Can Single‐Pass Electrofishing Replace Three‐Pass Depletion for Population Trend Detection?

AbstractSince changes in climate and land use operate at broad spatial scales, efficient monitoring of temporal trends in fisheries resources over large geographic areas is vital to appropriate management. We compared the statistical power of single‐ versus three‐pass electrofishing surveys in detecting temporal trends of age‐1 and older Brook Trout Salvelinus fontinalis populations in western North Carolina. Empirical estimates of abundance and capture probabilities were obtained from annual three‐pass depletion surveys at 14 headwater stream sites between 2012 and 2017. The CVs in abundance averaged 26% (SD = 14.2%) across study sites, and the mean capture probability per pass was 0.72 (range = 0.57–0.84, SD = 0.09). Captures from single‐pass sampling and abundance estimates from three‐pass removal sampling were highly correlated (r2 = 0.98). In simulations, under the range of years sampled (5–25 years) and annual declines (2.5–7.5%) considered, the power to detect temporal trends was similar (∆ power < 0.1) between the two methods when five or more sites were monitored. An additional set of simulations with varying capture probabilities demonstrated that differences in power between the two methods increased as mean capture probabilities decreased (0.8, 0.5, and 0.2) accompanied by larger variation in capture probabilities among the samples, indicating results obtained with Brook Trout populations in North Carolina might not be applicable to other habitat types or species. Variation in fish abundance did not affect the difference in power between the two methods. Single‐pass electrofishing surveys can be an efficient survey method to monitor temporal population trends for habitat types and species characterized with high capture probabilities and low variation among samples. However, single‐pass data would not typically allow for inferences of capture probabilities and thus abundance. This can be problematic when environmental factors vary and when data sets collected using different protocols are compared. This trade‐off should be carefully considered when designing monitoring programs.

6LiF:ZnS(Ag) Mixture Optimization for a Highly Efficient Ultrathin Cold Neutron Detector

We report the optimization of 6LiF:ZnS(Ag) scintillator mixtures for an ultrathin ( $\approx 30$ %). Our optimization took the form of exploring the weight ratios of neutron converter, phosphor, and binder to promote high neutron capture probability and light transport within the medium. We characterized a series of 6LiF:ZnS(Ag):binder mixtures for neutron absorption, light yield, and light transmission properties. In the process, we determined the optimal configuration for our requirements of millimeter thickness and cold neutron energy. Optimized prototypes exhibit excellent absorption and demonstrate neutron sensitivities of above 85% for 3.27-meV neutrons and gamma ray rejection ratios approaching 10−7.

Geolocation-Based Access for Vehicular Communications: Analysis and Optimization via Stochastic Geometry

LTE V2X is the response of the 3GPP standardization body to the high market expectations related to vehicular communications for safety and infotainment services. To fulfill the stringent requirements in terms of reliability associated with safety applications, geolocation-based access (GLOC) has been proposed for direct vehicle-to-vehicle (V2V) communication. Such a scheme aims at maximizing the distance of co-channel transmitters (i.e., transmitter that use the same resources) while preserving a low latency when accessing the resources and a low overhead. In this paper, we analyze, with the aid of stochastic geometry, the delivery of periodic and nonperiodic broadcast messages with GLOC, taking into account path loss and fading as well as the random locations of transmitting vehicles. Analytical results include the average interference, average binary rate, capture probability, i.e., the probability of successful message transmission, and energy efficiency (EE). Mathematical analysis reveals interesting insights about the system performance, which are validated through extensive Monte Carlo simulations. In particular, it is shown that the capture probability is an increasing function with exponential dependence with respect to the transmit power and it is demonstrated that an arbitrary high capture probability can be achieved, as long as the number of access resources is high enough. Finally, to facilitate the system-level design of GLOC, it is obtained the optimum transmit power, which fulfill a given minimum capture probability constraint while maximizing the EE of the system.

Optimization of 6LiF:ZnS(Ag) scintillator light yield using GEANT4

A new cold neutron detector has been developed at the NIST Center for Neutron Research (NCNR) for the CANDoR (Chromatic Analysis Neutron Diffractometer or Reflectometer) project. Geometric and performance constraints dictate that this detector be exceptionally thin (∼ 2 mm). For this reason, the design of the detector consists of a 6LiF:ZnS(Ag) scintillator with embedded wavelength shifting (WLS) fibers. We used the GEANT4 package to simulate neutron capture and light transport in the detector to optimize the composition and arrangement of materials to satisfy the competing requirements of high neutron capture probability and light production and transport. In the process, we have developed a method for predicting light collection and total neutron detection efficiency for different detector configurations.The simulation was performed by adjusting crucial parameters such as the scintillator stoichiometry, light yield, component grain size, WLS fiber geometry, and reflectors at the outside edges of the scintillator volume. Three different detector configurations were fabricated and their test results were correlated with the simulations. Through this correlation we have managed to find a common photon threshold for the different detector configurations which was then used to simulate and predict the efficiencies for many other detector configurations. New detectors that have been fabricated based on simulation results yielding the desired sensitivity of 90% for 3.27 meV (5 Å) cold neutrons.The simulation has proven to be a useful tool by dramatically reducing the development period and the required number of detector prototypes. It can be used to test new designs with different thicknesses and different target neutron energies.

Applying the multistate capture–recapture robust design to characterize metapopulation structure

Summary Population structure must be considered when developing mark–recapture (MR) study designs as the sampling of individuals from multiple populations (or subpopulations) may increase heterogeneity in individual capture probability. Conversely, the use of an appropriate MR study design which accommodates heterogeneity associated with capture occasion varying covariates due to animals moving between ‘states’ (i.e. geographic sites) can provide insight into how animals are distributed in a particular environment and the status and connectivity of subpopulations. The multistate closed robust design (MSCRD) was chosen to investigate: (i) the demographic parameters of Indo‐Pacific bottlenose dolphin (Tursiops aduncus) subpopulations in coastal and estuarine waters of Perth, Western Australia; and (ii) how they are related to each other in a metapopulation. Using 4 years of year‐round photo‐identification surveys across three geographic sites, we accounted for heterogeneity of capture probability based on how individuals distributed themselves across geographic sites and characterized the status of subpopulations based on their abundance, survival and interconnection. MSCRD models highlighted high heterogeneity in capture probabilities and demographic parameters between sites. High capture probabilities, high survival and constant abundances described a subpopulation with high fidelity in an estuary. In contrast, low captures, permanent and temporary emigration and fluctuating abundances suggested transient use and low fidelity in an open coastline site. Estimates of transition probabilities also varied between sites, with estuarine dolphins visiting sheltered coastal embayments more regularly than coastal dolphins visited the estuary, highlighting some dynamics within the metapopulation. Synthesis and applications. To date, bottlenose dolphin studies using mark–recapture approach have focussed on investigating single subpopulations. Here, in a heterogeneous coastal–estuarine environment, we demonstrated that spatially structured bottlenose dolphin subpopulations contained distinct suites of individuals and differed in size, demographics and connectivity. Such insights into the dynamics of a metapopulation can assist in local‐scale species conservation. The MSCRD approach is applicable to species/populations consisting of recognizable individuals and is particularly useful for characterizing wildlife subpopulations that vary in their vulnerability to human activities, climate change or invasive species.

Long-term density fluctuations and microhabitat use of sympatricApodemus flavicollisandMyodes glareolusin central Italy

The role and importance of interspecific competition for rodent communities have been much debated issues, with some early authors suggesting that these are important, and several recent articles suggesting the contrary. In this paper, we studied, for 14 years at a mountainous locality in central Italy, the coexistence dynamics of a two-species system (Apodemus flavicollis, Myodes glareolus) within a 1.44 ha trapping grid, by Capture-Mark-Recapture. Overall, we captured over 1000 rodents during the study period, with annual abundance ranging 2-7 individuals × ha−1. However, the density of the two species varied substantially across years and between sectors of the study plot. Thus, the distributions of the two species on the scale of the study grid were not related to one another. Density of a given species did not affect the percentage of lactating females in either A. flavicollis or M. glareolus. Individual traps differed in their rate of capture such that about 40% of traps were associated more with a particular species. Considering the spatial distribution of traps, we determined that three areas were associated with high probability of capture for only one of the two study species, two of these areas being associated to A. flavicollis and one to M. glareolus. Our analyses suggest that interspecific competition may be present at the local micro-scale, as explained by the fact that in the great majority of the cases in which a given trap was highly successful in capturing one species, it was also very unsuccessful in capturing the other species. However, manipulation experiments are needed to confirm that suggestion.

Gene Detection in Complex Biological Media Using Semiconductor Nanorods within an Integrated Microfluidic Device.

The salient optical properties of highly luminescent semiconductor nanocrystals render them ideal fluorophores for clinical diagnostics, therapeutics, and highly sensitive biochip applications. Microfluidic systems allow miniaturization and integration of multiple biochemical processes in a single device and do not require sophisticated diagnostic tools. Herein, we describe a microfluidic system that integrates RNA extraction, reverse transcription to cDNA, amplification and detection within one integrated device to detect histidine decarboxylase (HDC) gene directly from human white blood cells samples. When anisotropic semiconductor nanorods (NRs) were used as the fluorescent probes, the detection limit was found to be 0.4 ng of total RNA, which was much lower than that obtained using spherical quantum dots (QDs) or organic dyes. This was attributed to the large action cross-section of NRs and their high probability of target capture in a pull-down detection scheme. The combination of large scale integrated microfluidics with highly fluorescent semiconductor NRs may find widespread utility in point-of-care devices and multitarget diagnostics.

Enhancing sensitivity and specificity in rare cell capture microdevices with dielectrophoresis.

The capture and subsequent analysis of rare cells, such as circulating tumor cells from a peripheral blood sample, has the potential to advance our understanding and treatment of a wide range of diseases. There is a particular need for high purity (i.e., high specificity) techniques to isolate these cells, reducing the time and cost required for single-cell genetic analyses by decreasing the number of contaminating cells analyzed. Previous work has shown that antibody-based immunocapture can be combined with dielectrophoresis (DEP) to differentially isolate cancer cells from leukocytes in a characterization device. Here, we build on that work by developing numerical simulations that identify microfluidic obstacle array geometries where DEP-immunocapture can be used to maximize the capture of target rare cells, while minimizing the capture of contaminating cells. We consider geometries with electrodes offset from the array and parallel to the fluid flow, maximizing the magnitude of the resulting electric field at the obstacles' leading and trailing edges, and minimizing it at the obstacles' shoulders. This configuration attracts cells with a positive DEP (pDEP) response to the leading edge, where the shear stress is low and residence time is long, resulting in a high capture probability; although these cells are also repelled from the shoulder region, the high local fluid velocity at the shoulder minimizes the impact on the overall transport and capture. Likewise, cells undergoing negative DEP (nDEP) are repelled from regions of high capture probability and attracted to regions where capture is unlikely. These simulations predict that DEP can be used to reduce the probability of capturing contaminating peripheral blood mononuclear cells (using nDEP) from 0.16 to 0.01 while simultaneously increasing the capture of several pancreatic cancer cell lines from 0.03-0.10 to 0.14-0.55, laying the groundwork for the experimental study of hybrid DEP-immunocapture obstacle array microdevices.

Multi-state mark-recapture models as a novel approach to estimate factors affecting attendance patterns of lactating subantarctic fur seals from Marion Island

AbstractObserver-based studies often underestimate key ecological parameters. Here a fresh approach was used to analyse six years (2006–11) of attendance cycles to estimate foraging trip lengths of a lactating flipper-tagged otariid: subantarctic fur seals at Marion Island. Multi-state mark-recapture models were used to calculate detection failures of females, correct estimates accordingly, and investigate the effects of year, season, pup sex and the presence of a telemetry device on attendance cycle parameters. There were no differences between corrected and uncorrected attendance data. This is attributed to the high capture probability across all seasons (range: 83–98%). This illustrates that observer-based studies are useful to augment telemetry studies. Only season and pup sex had a significant impact on female provisioning rates. In winter, foraging trip durations were longer (t-value=25.22,P<0.0001) and attendance durations shorter (t-value=-2.15,P=0.01) than during summer. Females with female pups spent a higher proportion of their time on land (χ2=6.6,P<0.05). Male pups have higher growth demands and are larger which suggests they can deplete female milk-stores faster.

Long-term trends in the use of a protected area by small cetaceans in relation to changes in population status

The requirement to monitor listed species in European designated sites is challenging for long-lived mobile species that only temporarily occupy protected areas. We use a 21 year time series of bottlenose dolphin photo-identification data to assess trends in abundance and conservation status within a Special Area of Conservation (SAC) in Scotland. Mark–recapture methods were used to estimate annual abundance within the SAC from 1990 to 2010. A Bayesian mark–recapture model with a state-space approach was used to estimate overall population trends using data collected across the populations’ range. Despite inter-annual variability in the number of dolphins within the SAC, there was a >99% probability that the wider population was stable or increasing. Results indicate that use of the SAC by the wider population has declined. This is the first evidence of long-term trends in the use of an EU protected area by small cetaceans in relation to changes in overall population status. Our results highlight the importance of adapting the survey protocols used in long-term photo-identification studies to maintain high capture probabilities and minimise sampling heterogeneity. Crucially, these data demonstrate the value of collecting data from the wider population to assess the success of protected areas designated for mobile predators.