Search Results (22)

Flapping-wing drones (FWDs), owing to their compact size and operation in cluttered and unsteady airflow environments, encounter significant aerodynamic and stability challenges. Studies of avian flight reveal that falcons and other raptors actively deflect their covert feathers to mitigate gusts and maintain stable flight. Drawing inspiration from this mechanism, this study presents a peregrine falcon-inspired Active Flow Control Unit (AFCU) integrated with a Deep Deterministic Policy Gradient (DDPG)-based deep reinforcement learning (DRL) controller for real-time disturbance attenuation. The AFCU employs mechanical covert feathers (MCFs) that actuate to dissipate gust loads during high wind conditions. A reduced-order bond graph model that encapsulates the nonlinear interaction between the primary wing and the feather-based active flow control surfaces is created which is used as a dynamic training environment for the DDPG agent. Utilizing closed-loop interactions, the successfully obtained learned policy produces optimal actuator forces to reduce feather-displacement error and aerodynamic load variations. The designed controller stabilizes the internally unstable open-loop AFCU, attaining near-zero steady-state error and settling times under 1.6 s for gust magnitudes ranging from 12.5 to 20 m/s. Simulations further illustrate a reduction of up to 50% in gust-induced loads compared to traditional approaches. This integration of bio-inspired design with learning-based active flow control offers a viable avenue for the development of highly adaptive and gust-resilient flapping-wing aerial systems. Full article

To simultaneously improve mass transfer and minimize pressure drop in proton exchange membrane fuel cells (PEMFCs), this study proposes a novel bionic flow field inspired by the streamlined abdominal structure of the peregrine falcon. A three-dimensional channel geometry is developed from this biological prototype and integrated into a single-channel PEMFC model for numerical simulation. A series of computational fluid dynamics (CFD) analyses compare the new design against conventional straight, trapezoidal, and sinusoidal flow fields. The results demonstrate that the falcon-inspired configuration enhances oxygen delivery, optimizes water management, and achieves a more uniform current density distribution. Remarkably, the design delivers a 9.45% increase in peak power density while significantly reducing pressure drop compared to the straight channel. These findings confirm that biologically optimized aerodynamic structures can provide tangible benefits in PEMFC flow field design by boosting electrochemical performance and lowering parasitic losses. Beyond fuel cells, this bio-inspired approach offers a transferable methodology for advanced energy conversion systems where efficient fluid transport is essential. Full article

The peregrine falcon, known as the fastest bird in the world, has been studied for its ability to stabilize during high-speed dives, a capability attributed to the configuration of its dorsal feathers. These feathers have inspired the design of vortex generators devices that promote controlled turbulence to delay boundary layer separation on aircraft wings and turbine blades. This study presents an experimental wind tunnel investigation of a bio-inspired peregrine falcon prototype, equipped with movable artificial feathers, a hot-wire anemometer, and a 3D accelerometer. Wake velocity profiles measured behind the prototype revealed fluctuations associated with feather motion. Spectral analysis of the velocity signals, recorded with oscillating feathers at a wind tunnel speed of 10 m/s, showed attenuation of specific frequency components, suggesting that feather dynamics may help mitigate wake fluctuations induced by structural vibrations. Three-dimensional acceleration measurements indicated that prototype vibrations remained below 1 g, with peak differences along the X and Z axes ranging from −0.06 g to 0.06 g, demonstrating the sensitivity of the vibration sensing system. Root Mean Square (RMS) values of velocity signals increased with wind tunnel speed but decreased as the feather inclination angle rose. When the mean value was subtracted from the signal, higher RMS variability was observed, reflecting increased flow disturbance from feather movement. Fast Fourier Transform (FFT) analysis revealed that, for fixed feather angles, spectral magnitudes increased uniformly with wind speed. In contrast, dynamic feather oscillation produced distinctive frequency peaks, highlighting the feather’s influence on the wake structure in the frequency domain. To complement the experimental findings, 3D CFD simulations were conducted on two HAWT-type wind turbines—one with bio-inspired vortex generators and one without. The simulations showed a significant reduction in turbulent kinetic energy contours in the wake of the modified turbine, particularly in the Y-Z plane, compared to the baseline configuration. Full article

Captive birds of prey often exceed their wild counterparts’ lifespan, as seen in bald eagles (Haliaeetus leucocephalus, ~20 years wild vs. ~40 years captive), golden eagles (Aquila chrysaetos, ~32 years wild vs. ~46 years captive), and Andean condors (Vultur gryphus, ~50 years wild vs. ~79 years captive), highlighting the impact of controlled environments on longevity. However, recent evidence suggests a rising incidence of neoplastic processes in these species. While previous studies have indicated a higher-than-expected prevalence of neoplasia in raptors, comprehensive research on this topic remains scarce. Squamous cell carcinoma (SCC), a frequently reported neoplasm in pet birds, has been documented in birds of prey, though the literature on its prevalence and management is limited. Retrospective studies have identified SCC cases in peregrine falcons (Falco peregrinus), primarily affecting the flank or thigh, with locally invasive behavior and rare distant metastasis. Complete surgical excision is the preferred treatment for SCCs, yet its feasibility is often constrained by tumor invasiveness and anatomical limitations. Electrochemotherapy (ECT) has emerged as a promising alternative, utilizing electroporation to enhance intracellular drug uptake while minimizing systemic toxicity. Bleomycin and cisplatin have been successfully used in avian intralesional chemotherapy, offering a potentially safer and effective treatment approach. ECT has demonstrated efficacy in various exotic species, yet its application in raptors remains largely unexplored. This case report describes the use of electrochemotherapy with bleomycin in a peregrine falcon diagnosed with SCC, contributing to the growing body of evidence supporting its clinical utility in avian oncology. Full article

We conducted a helicopter survey in 2010 for cliff-nesting raptors along the Dalton Highway in northern Alaska. The study area extended from the Yukon River northward ~395 km through the Brooks Range to the Arctic Plain. We documented 55 occupied raptor nesting territories, including 25 Golden Eagle (Aquila chrysaetos), 11 Gyrfalcon (Falco rusticolus), and 10 Peregrine Falcon (Falco peregrinus) territories. We also recorded vacant stick nests and raptor perch sites on cliffs. We identified more occupied eagle territories and hundreds more vacant eagle stick nests than were previously known in the study area. The average number of Golden Eagle nestlings/nesting pairs at the time of the survey was 1.5 ± 0.6. The most productive Golden Eagle pairs were located in the northern part of the study area. The number of occupied eagle territories in 2010 is far fewer than the number of eagle stick nests we recorded. Our data indicate that the distribution of nesting eagles in the 2010 study area is different than in the past. Whether this reflects changes in eagle density; a response to availability of prey, climate change, human activities, or a combination of these; or some other factor warrants further investigation. Intensive surveys along the Dalton Highway in the 1970s found no occupied nests for Peregrine Falcons or Gyrfalcons but we found 10 and 11, respectively. Therefore, the Peregrine Falcon and Gyrfalcon nests we recorded in 2010 reflect an increase in the number of known nesting pairs there. Full article

Highly pathogenic avian influenza (HPAI) epizootics have caused repeated mass mortality events among wild birds. The effect of the infection is potentially detrimental for a variety of bird species, including the Peregrine Falcon (Falco peregrinus). The numbers of wintering and breeding Peregrine Falcons in the Netherlands have recently declined. We investigated the changes in population trends in relation to HPAI H5 virus outbreaks. For this purpose, we analyzed variations in annual numbers of wintering and breeding birds, the virology of reported dead birds, and the presence of the HPAI H5 virus in unhatched eggs. We showed that significant mortalities of Peregrine Falcons had occurred in 2016–2017 and 2020–2023, years of major HPAI H5 virus outbreaks. In particular, the highest rates of bird mortality and HPAI virus infection were reported in 2023. In this year, over 80% (28/32) of the tested birds were positive for HPAI H5 virus. No HPAI H5 virus was present in the eggs. Based on these findings, we concluded that HPAI represents a serious threat to the Peregrine Falcon population in the Netherlands, and, in combination with anthropogenic factors, may contribute to the decline of this species. Targeted HPAI surveillance and disease mitigation measures are necessary for the conservation of this species. Full article

The peregrine falcon (Falco peregrinus) stands out as a crucial sentinel species for assessing environmental contamination, owing to its widespread distribution, high position in the food chain, and susceptibility to pollutants. As apex predators, these remarkable birds accumulate various contaminants found in their prey, thus serving as valuable indicators of ecological health. The historical application of organochlorine pesticides, such as DDT, resulted in alarming population declines, highlighting the significant vulnerability of peregrines to environmental hazards. Recent research has shed light on the detrimental effects of heavy metal exposure, revealing critical health risks including compromised immune function and reduced reproductive success, which further highlight the ecological consequences of pollution for top predators. Moreover, the complex nature of brominated flame retardants poses challenges in balancing fire safety with environmental health, as these chemicals persist in the ecosystem and threaten peregrine falcon populations. In the future, the use of possible new bioindicators of environmental pollution opens up interesting prospects. This innovative approach may enhance our understanding of how contaminants affect reproductive health and contribute to a broader One Health perspective, emphasizing the interconnectedness of wildlife, human health, and ecosystem integrity. This comprehensive overview underscores the urgency of ongoing monitoring and regulatory efforts to protect peregrine falcons and, by extension, our shared environment. Full article

This article describes a quadcopter drone with foldable arms, which we have named the Peregrine Falcon. It can take off from a moving vehicle by barrel launching and perform its mission in the air after autonomously spreading its arms. The design helps the drone to be put into operation quickly, which is a great advantage for applications in industries such as forest fire reconnaissance. This paper introduces the design process of the Peregrine Falcon from the aspects of structure, avionics and control algorithm, and proposes control compensation methods for the large attitude change generated during the barrel launching process and the vertical drift problem after impact, respectively. The stability and feasibility of the Peregrine Falcon in the static and dynamic launching process are verified by flying experiments. Full article

Rewilding attempts to increase biodiversity and restore natural ecosystem processes by reducing human influence. Today, there is growing interest in rewilding urban areas. Rewilding of the Detroit, Michigan, USA and Windsor, Ontario, Canada metropolitan area, and its shared natural resource called the Detroit River, has been delineated through the reintroduction of peregrine falcons and osprey, and a return of other sentinel species like bald eagles, lake sturgeon, lake whitefish, walleye, beaver, and river otter. Rewilding has helped showcase the value and benefits of environmental protection and restoration, ecosystem services, habitat rehabilitation and enhancement, and conservation, including social and economic benefits. Improved ecosystem health and rewilding have become a catalyst for re-establishing a reconnection between urban denizens and natural resources through greenways and water trails. The provision of compelling outdoor experiences in nature, in turn, can help foster a personal attachment to the particular place people call home that can help inspire a stewardship ethic. Full article

In the fall of 2022, high pathogenicity avian influenza viruses (HPAIVs) were detected from raptors and geese in Japan, a month earlier than in past years, indicating a shift in detection patterns. In this study, we conducted a phylogenetic analysis on H5N1 HPAIVs detected from six wild birds during the 2022/2023 season to determine their genetic origins. Our findings revealed that these HPAIVs belong to the G2 group within clade 2.3.4.4b, with all isolates classified into three subgroups: G2b, G2d, and G2c. The genetic background of the G2b virus (a peregrine falcon-derived strain) and G2d viruses (two raptors and two geese-derived strains) were the same as those detected in Japan in the 2021/2022 season. Since no HPAI cases were reported in Japan during the summer of 2022, it is probable that migratory birds reintroduced the G2b and G2d viruses. Conversely, the G2c virus (a raptor-derived strain) was first recognized in Japan in the fall of 2022. This strain might share a common ancestor with HPAIVs from Asia and West Siberia observed in the 2021/2022 season. The early migration of waterfowl to Japan in the fall of 2022 could have facilitated the early invasion of HPAIVs. Full article

Vortex generators are used in aircraft wings and wind turbine blades. These devices allow them to maintain a stable turbulent behavior in the wind wake. Vortex generators, or VGs, improve the transition from laminar to turbulent boundary layer regime, avoiding abrupt shedding. HAWT wind turbines have high rotational velocity. Currently, HAWT turbines are being redesigned with fixed vortex generators, achieving higher energy production. This paper presents a wind tunnel analysis of a fixed-wire blade with S822 airfoil and active VGs bio-inspired by the flight-stabilizing feathers of the peregrine falcon. Vibrations measured on the blade show a reduction in intensity at wind velocities close to 15 m/s. The measured wake velocities show fluctuations at higher tunnel wind velocities. An FFT spectral analysis of the wind wake velocities showed differences between the spectral components. When activating the VGs in oscillation at a constant frequency, a reduction of the vibrations on the blade was observed for wind velocities around 20 m/s. Full article

Vortex generators are devices that modify the wind behavior near the surface of wind turbine blades. Their use allows the boundary layer shedding transition zone to be varied. Bio-inspired design has been used to improve the efficiency of aerodynamic and hydrodynamic systems by creating devices that use shapes present in animals and plants. In this work, an experimental methodology is proposed to study the effect of bio-inspired vortex generators and their effect on the structural vibration of a blade. In addition, the wind wake generated by the blade with oscillating vortex generators at different oscillation frequencies is analyzed by means of a hot wire anemometer, obtaining appreciable vibration reduction results in the measured 3D acceleration signals for wind velocities between 10 and 15 m/s. Values of the spectral components of the wake velocity measured at higher tunnel wind velocities increase. Spectral variance is reduced at higher tunnel wind velocities. The system analyzed in this paper can contribute in the future to the construction of actuators for vibration compensation systems in wind turbines. Full article

Currently, the illegal wildlife trade is one of the most profitable illegal enterprises in the world. The aim of our study was to determine the situation with respect to wildlife trade in Slovenia, which is mainly a transit country, before changes to the Schengen borders came into effect. The volume of trade is significant but not extensive. The most common endangered species involved in illegal trade in Slovenia are the brown bear, the peregrine falcon, the date mussel, the lady’s slipper orchid, the common snowdrop, the cyclamen, the sea turtle, the otter, and various reptile species. The smuggling of shells (date shells), ivory (ivory products), certain plants, and various hunting trophies (bears, big cats) has decreased in recent years. Nevertheless, counteracting crimes continues to be important for the conservation of some species in Slovenia, notably the lynx, and for the reduction of poaching. Improvements are needed in the detection and prevention of wildlife crime, especially in light of changes made to the Schengen borders and the consequent inclusion of new trading partners for Slovenia. The lack of people properly trained to identify, detect, and investigate wildlife crime is especially acute. Full article

The main objective of this study was to determine the impact of increased demand for peregrine falcons via breeding (mainly Polish, Czech, German and Slovak) on the genetic structure of the birds. In the analysis, 374 specimens from six countries were sampled in 2008–2019 (omitting 2009), and all the birds analyzed were released into the wild as part of the Polish reintroduction program. The assessment of genetic variation was based on a well-known panel of 10 microsatellite markers described for the species. We calculated a fixation index for the samples from each year, and based on this, we determined the level of inbreeding. We also performed an analysis using the Bayesian cluster method, assuming that 1–19 hypothetical populations would define the division that best fit the samples. The most probable division was into two groups; in the first group, the samples from individuals delivered in 2013 were most often segregated; moreover, in this year, a jump in inbreeding, expressed by the fixation index, was observed. Full article