Birds Fly Research Articles

Estimación de la altura de vuelo en aves

Knowing the species and the altitude at which birds fly is crucial for establishing measures to minimize the probability of collisions with aircraft or wind turbines. There are many sophisticated methods to determine the flight altitude of birds, although not all are accessible to everyone. Two steps based on trigonometric principles can be used to estimate flight altitude. The validity of the results depends on the assumptions of the method. Despite the robustness of trigonometric principles, observer biases in data collection can affect accuracy. However, this tool is much more effective, realistic, and economical compared to other methods.

Surveillance of avian influenza viruses in Hebei Province of China from 2021 to 2023: Identification of a novel reassortant H3N3

Avian influenza remains a global public health concern for its well-known point mutation and genomic segment reassortment, through which plenty of serum serotypes are generated to escape existing immune protection in animal and human populations. Some occasional cases of human infection of avian influenza viruses (AIVs) since 2020 posed a potential pandemic risk through human-to-human transmission. Both east-west and north-south migratory birds fly through and linger in the Hebei Province of China as a stopover habitat, providing an opportunity for imported AIVs to infect the local poultry and for viral gene reassortment to generate novel stains. In this study, we collected more than 6000 environmental samples (mostly feces) in Hebei Province from 2021 to 2023. Samples were screened using real-time RT-PCR, and virus isolation was performed using the chick embryo culture method. We identified 10 AIV isolates, including a novel reassortant H3N3 isolate. Sequencing analysis revealed these AIVs are highly homologous to those isolated in the Yellow River Basin. Our findings supported that AIVs keep evolving to generate new isolates, necessitating a continuous risk assessment of local avian influenza in wild waterfowl in Hebei, China.

Energy supply during nocturnal endurance flight of migrant birds: effect of energy stores and flight behaviour

BackgroundMigrating birds fly non-stop for hours or even for days. They rely mainly on fat as fuel complemented by a certain amount of protein. Studies on homing pigeons and birds flying in a wind-tunnel suggest that the shares of fat and protein on total energy expenditure vary with flight duration and body fat stores. Also, flight behaviour, such as descending flight, is expected to affect metabolism. However, studies on free flying migrant birds under natural conditions are lacking.MethodsOn a Swiss Alpine pass, we caught three species of nocturnal migrant passerines out of their natural migratory flight. Since most night migrants start soon after dusk, we used time since dusk as a measure of flight duration. We used plasma concentrations of metabolites of the fat, protein, and carbohydrate metabolism as indicators of relative fuel use. We used flight altitudes of birds tracked with radar and with atmospheric pressure loggers to characterize flight behaviour.ResultsThe indicators of fat catabolism (triglycerides, very low-density lipoproteins, glycerol) were positively correlated with body energy stores, supporting earlier findings that birds with high fat stores have a higher fat catabolism. As expected, plasma levels of triglycerides, very low-density lipoproteins, glycerol and ß-hydroxy-butyrate increased at the beginning of the night, indicating that nocturnal migrants increased their fat metabolism directly after take-off. Surprisingly, fat catabolism as well as glucose levels decreased in the second half of the night. Data from radar observations showed that the number of birds aloft, their mean height above ground and vertical flight speed decreased after midnight. Together with the findings from atmospheric pressure-loggers put on three species, this shows that nocturnal migrants migrating over continental Europe descend slowly during about 1.5 h before final landfall at night, which results in 11–30% energy savings according to current flight models.ConclusionsWe suggest that this slow descent reduces energy demands to an extent which is noticeable in the plasma concentration of lipid, protein, and carbohydrate metabolites. The slow descent may facilitate the search for a suitable resting habitat and serve to refill glycogen stores needed for foraging and predator escape when landed.

Drivers of flight altitude during nocturnal bird migration over the North Sea and implications for offshore wind energy

AbstractEach year, millions of birds migrate nocturnally over the North Sea basin, an area designated for significant offshore wind energy development. Wind turbines can harm aerial wildlife through collisions and barrier effects, especially when birds fly at low altitudes below the wind turbine rotor tip. We aim to quantify seasonal and nightly differences in flight altitudes of nocturnal bird migration over the North Sea and identify how weather influences low‐altitude flight to inform wind turbine curtailment procedures for reducing bird fatalities. We used bird tracking radars at Borssele and Luchterduinen offshore wind parks, 22 and 23 km from the western Dutch coast, to monitor altitude distributions during migration. We show that median flight altitude was higher in spring compared to autumn at Borssele (spring: 285.5 m, autumn: 169.2 m; p < .001, effect size [ES] = 0.0001) and Luchterduinen (spring: 133.8 m, autumn: 126.0 m; p < .001, ES = 0.002) and below wind turbine rotor tip in both seasons. On most nights in both seasons, the majority of migrants flew predominantly at low altitudes, except for intense migration nights in spring in Borssele where, on 87% of these nights, migration mainly occurred at high altitudes. The most important predictors of low‐altitude migration in both seasons were day of year and wind assistance. Birds chose altitudes with the most favorable wind conditions for migration in both seasons. The relationship between day of year and low‐altitude migration fraction suggests that different species migrate at different altitudes. In spring, birds were flying lower at the beginning and the end of the night, reflecting departures and arrivals of birds, while radar location in autumn was a good predictor of low‐altitude flights, indicating that different local migratory axes have distinct altitude distributions. Our findings suggest that mitigation measures offshore may be more effective during autumn than spring, especially on nights with more supportive wind conditions at altitudes below 300 m.

American Alligator (Alligator mississippians) Behavioral Ecology on the FGCU Campus

Wild animals often travel deeper into urban areas than they realize and find themselves confronted with an environment they do not understand. They may wander into heavily trafficked areas, get hit by cars, get frightened by people, and–if the animal happens to be a bird–fly into glass (Threats to wildlife 2018). The top predator, the American Alligator (Alligator mississippians) is one of the native animals that still call Florida Gulf Coast University its home. The purpose of this research is to better understand how human activity and development affects the behaviors of the American Alligators (Alligator mississippians) at Florida Gulf Coast University. Interactions between humans and alligators have become more frequent, so understanding how human presence and activity changes the detectability of these alligators is important to their long-term management on a human dominated landscape (Kidd-Weaver et al., 2022). This study focused on the ability to track radio-tagged alligators toward a visual sighting and whether this changes with time of day or location on campus.This project built on a previous study where alligators on the FGCU campus were captured, measured and gender identified, radio-tagged, and released. This part of the study focused on the spatial ecology on movements of the American Alligators based on gender. This phase of the study focused on the time of day they can be found and how this varies between more, to less developed parts of the campus.

Northward migration of Red Knots Calidris canutus rufa and environment connectivity of southern Brazil to Canada

Summary During their northward migration, Red Knots Calidris canutus rufa stop at the Lagoa do Peixe National Park in the extreme south of Brazil to build up fat reserves for their journey to their Canadian breeding grounds. We tracked five Red Knots with PinPoint Argos-75 GPS transmitters to investigate differences in migration strategies from this stopover. Tracked birds used two different routes: the Central Brazil route and the Brazilian Atlantic Coast route. One bird flew 8,300 km straight from Lagoa do Peixe to the Delaware Bay (USA). Another bird stopped in Maranhão (north-east Brazil) and a third one used a yet unknown environment for the species, the mouth of the Amazon River at Baía Santa Rosa, Brazil. These two birds made short flights, covering stretches of 1,600 km to 3,600 km between stop-overs, where they stayed from 4 to 18 days. Our study highlights the occurrence of intrapopulation variation in migratory strategies and reveals the connectivity of environments that are essential for the viability of rufa Red Knot populations.

Numerical Simulation and Flow Display of Bionic Alula on Rectangle Airfoils

Some birds have small wings (Alula) in the middle of their main wings. These small wings will tilt upward when the bird flies at a high attack angle to maintain a stable flying posture. This paper explores the lift effects of bionic Alula on rectangular airfoils with different aspect ratios through numerical simulation and flow display experiments. According to the numerical simulation, Alula can increase the rectangular airfoil lift coefficient by a maximum of 24% when the airfoil aspect ratio is 2. By comparing simulation results with flow display results, the low-pressure area generated by Alula and the merge of the Alula vortices with the airfoil tip vortices mainly contribute to the lift enhancement.

Visual guidance of honeybees approaching a vertical landing surface.

Landing is a critical phase for flying animals, whereby many rely on visual cues to perform controlled touchdown. Foraging honeybees rely on regular landings on flowers to collect food crucial for colony survival and reproduction. Here, we explored how honeybees utilize optical expansion cues to regulate approach flight speed when landing on vertical surfaces. Three sensory-motor control models have been proposed for landings of natural flyers. Landing honeybees maintain a constant optical expansion rate set-point, resulting in a gradual decrease in approach velocity and gentile touchdown. Bumblebees exhibit a similar strategy, but they regularly switch to a new constant optical expansion rate set-point. In contrast, landing birds fly at a constant time to contact to achieve faster landings. Here, we re-examined the landing strategy of honeybees by fitting the three models to individual approach flights of honeybees landing on platforms with varying optical expansion cues. Surprisingly, the landing model identified in bumblebees proved to be the most suitable for these honeybees. This reveals that honeybees adjust their optical expansion rate in a stepwise manner. Bees flying at low optical expansion rates tend to increase their set-point stepwise, while those flying at high optical expansion rates tend to decrease it stepwise. This modular landing control system enables honeybees to land rapidly and reliably under a wide range of initial flight conditions and visual landing platform patterns. The remarkable similarity between the landing strategies of honeybees and bumblebees suggests that this may also be prevalent among other flying insects. Furthermore, these findings hold promising potential for bioinspired guidance systems in flying robots.

Lord I Thought at Least You’d Be Here, and: With Each Bird Flying, Time Is Passing

Lord I Thought at Least You’d Be Here, and: With Each Bird Flying, Time Is Passing

An Intensional Formalization of Generic Statements

A statement is generic if it expresses a generalization about the members of a kind, as in, ’Pear trees blossom in May,’ or, ’Birds lay egg’. In classical logic, generic statements are formalized as universally quantified conditionals: ‘For all x, if..., then....’ We want to argue that such a logical interpretation fails to capture the intensional character of generic statements because it cannot express the generic statement as a simple proposition in Aristotle’s sense, i.e., a proposition containing only one single predicate. On the contrary, we want to show that typed lambda-abstraction can help us transform the classical, non-simple and extensional expression of generic statements into a new, simple and intensional formalization, through the introduction of an abductively defined operator ALL*. This new operator allows for the possibility of a single predication, e.g. fly(), because it builds, out of a concept like ‘bird’, a concrete universal, e.g. ‘birds’, upon which the single predicate can be applied to authentically formalize a generic statement, e.g. ‘birds fly’.

Культ орла в мифологии хангаласцев

Культ орла в мифологии хангаласцев

Steppe Eagle’s population structure migrating through the bottleneck of Eilat in spring

Steppe Eagles (Aquila nipalensis) migrate in large numbers past key migration flyways from almost its entire breeding region. On its spring migration route from Africa many birds fly through the bottleneck of Eilat in southern Israel. Migration timing and age structures in the population are often key elements of conservation works. In the four springs of 2015 to 2018 we systematically counted the passing Steppe Eagles at two count stations. An average of 15,039 Steppe Eagles were counted per spring. We also recorded the ages of many of the Eagles. We found patterns in the Eagle's migration that is related to the age of the eagles. Adults arrive early and are most abundant, followed by sub adults, and juveniles in timing and numbers. Furthermore, we compared our data of the structure of the passing populations with different flyways and wintering sites and found significant differences. The flyway in Eilat is mostly occupied by adult migrating birds, 72% of the aged birds were adults in the survey. The different usage of flyways by ages can be an important factor in future conservation projects.

Post-fledging distribution of ’ua’u (Hawaiian petrel Pterodroma sandwichensis) from Kaua’i, Hawai’i and effectiveness of rehabilitation

The ‘ua’u (Hawaiian petrel Pterodroma sandwichensis) is an Endangered seabird endemic to the Hawaiian Islands. The at-sea distribution of this species is an under-studied aspect of its ecology. We tracked 10 petrels fledging from the island of Kaua’i to their first wintering grounds, an area which has not previously been described. We also compare birds fledging naturally from their burrows with birds that were grounded by light attraction, rehabilitated, and released. All fledglings travelled over 2000 km southwest after leaving Kaua’i until they reached the Inter-Tropical Convergence Zone and the frontal zone that separates the westward-flowing North Equatorial Current from the eastward-flowing North Equatorial Counter Current. At this point, birds still transmitting turned west, passing through Micronesia before eventually reaching the Philippines. Three birds entered the Lagonoy Gulf in the Philippines, 2 birds briefly entered the South China Sea and the waters off Taiwan, and 1 bird flew up to Japan before returning to the waters off the Philippines. The core use area within the wintering ground was characterized by higher temperatures, lower sea level anomaly, and higher chlorophyll a concentrations. While wild fledglings transmitted longer than rehabilitated birds, this was only weakly significant, and the fact that several rehabilitated birds made it to their first wintering grounds highlights the importance of rescue and rehabilitation efforts. The potential threats to birds over-wintering in this area include concentrated fishing activity in the Lagonoy Gulf, nocturnal squid fishing vessels across the region, marine pollution, and the impacts of climate change to the region’s marine environment.

:Dreams of Birds Flying in the Sky

Previous articleNext article No AccessMedia ReviewsDreams of Birds Flying in the Sky directed by Arun Bhattarai and produced by Matthew Schuelka. Fora Films, 2021. 58 minutes.Matthew J. SchuelkaMatthew J. SchuelkaUniversity of Minnesota; Fora Films, a division of Fora Education Search for more articles by this author PDFPDF PLUSFull Text Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by Comparative Education Review Volume 66, Number 4November 2022 Sponsored by the Comparative and International Education Society Article DOIhttps://doi.org/10.1086/722117 Views: 18Total views on this site For permission to reuse, please contact [email protected]PDF download Crossref reports no articles citing this article.

Updated taxonomic keys for European Hippoboscidae (Diptera), and expansion in Central Europe of the bird louse fly Ornithomyacomosa (Austen, 1930) with the first record from Slovakia.

The available keys for European Hippoboscidae are outdated and do not cover all species currently known from Europe. Therefore, identification keys to the eleven genera and 31 species of the European hippoboscids are provided here. Ornithomyacomosa (Austen, 1930) (Diptera: Hippoboscidae) is recorded for the first time from the territory of Slovakia based on one female found on a sand martin, Ripariariparia (Linnaeus, 1758). The list of keds and louse flies recorded from the territory of Slovakia is increased to 20 species. New host records for Slovakia are presented.

Commentary on Thomas Aquinas's Treatise on Happiness and Ultimate Purpose by J. Budziszewski, Cambridge University Press, Cambridge, 2020, pp. xxxvi + 666, £120.00, hbk

Commentary on Thomas Aquinas's <i>Treatise on Happiness and Ultimate Purpose</i> by J. Budziszewski, Cambridge University Press, Cambridge, 2020, pp. xxxvi + 666, £120.00, hbk

Avian whiffling-inspired gaps provide an alternative method for roll control

Some bird species exhibit a flight behavior known as whiffling, in which the bird flies upside-down during landing, predator evasion, or courtship displays. Flying inverted causes the flight feathers to twist, creating gaps in the wing’s trailing edge. It has been suggested that these gaps decrease lift at a potentially lower energy cost, enabling the bird to maneuver and rapidly descend. Thus, avian whiffling has parallels to an uncrewed aerial vehicle (UAV) using spoilers for rapid descent and ailerons for roll control. However, while whiffling has been previously described in the biological literature, it has yet to directly inspire aerodynamic design. In the current research, we investigated if gaps in a wing’s trailing edge, similar to those caused by feather rotation during whiffling, could provide an effective mechanism for UAV control, particularly rapid descent and banking. To address this question, we performed a wind tunnel test of 3D printed wings with a varying amount of trailing edge gaps and compared the lift and rolling moment coefficients generated by the gapped wings to a traditional spoiler and aileron. Next, we used an analytical analysis to estimate the force and work required to actuate gaps, spoiler, and aileron. Our results showed that gapped wings did not reduce lift as much as a spoiler and required more work. However, we found that at high angles of attack, the gapped wings produced rolling moment coefficients equivalent to upwards aileron deflections of up to 32.7° while requiring substantially less actuation force and work. Thus, while the gapped wings did not provide a noticeable benefit over spoilers for rapid descent, a whiffling-inspired control surface could provide an effective alternative to ailerons for roll control. These findings suggest a novel control mechanism that may be advantageous for small fixed-wing UAVs, particularly energy-constrained aircraft.

Automated execution of a pest bird deterrence system using a programmable unmanned aerial vehicle (UAV)

Crop damage caused by pest birds is a big problem around the world. As many studies have shown, existing bird control methods have not met growers' expectations regarding efficacy, reliability, and cost. Researchers are investigating the potential of using unmanned aerial vehicles (UAVs) as a tool for bird deterrence in agricultural fields to address this challenge. UAV-based bird deterrence techniques investigated in the past needed human operators to locate bird flocks and fly UAVs to desired trajectories. This study focused on automating a UAV-based bird deterrence system to operate it in real-time. Specifically, we focused on; i) optimizing the existing machine vision system to detect and locate birds-like movement in a real-time; ii) dynamically creating and launching two intelligent UAV missions in real-time to scare incoming birds (target intercept mission) or birds that are already inside the field (field patrol mission); and iii) executing these missions independently (short duration mission) as well as jointly (longer missions with more variation) in a vineyard using a programmable UAV. Outdoor experiment was conducted to evaluate the mission execution efficiency of the proposed system using a programmable UAV without a built-in global positioning system (GPS). Simulated bird movements generated using waving human hands were used for evaluating the target intercept mission. Results show that the algorithms developed for automated operation completed ∼92% of the assigned tasks successfully during shorter mission and 90% of the task during longer mission. Despite, successful execution of algorithms, the automated system experienced major shortcomings due to the lack of GPS for navigation of the UAV, which can be improved using a GPS-enabled programmable UAV. Future work also includes full scale field evaluation using machine vision system to identify actual incoming birds to determine the efficiency in deterring birds in commercial operations.

These birds fly high when the full Moon hangs in the sky

These birds fly high when the full Moon hangs in the sky

Stopover use of a large estuarine wetland by dunlins during spring and autumn migrations: Linking local refuelling conditions to migratory strategies.

Migratory strategies dictate stopover ecology, particularly concerning decisions of when, where and how long to stop, and what to do at stationary periods. In birds, individuals stop primarily to replenish energy stores, although the functions of stopover events vary among and within species, particularly between pre- and post-breeding seasons. Here, we combined plasma metabolite levels and haematological parameters to compare refuelling rates and physiological state within (early, mid, late) and between (spring, autumn) migratory periods, aiming to identify potentially different migratory strategies in a shorebird, the dunlin Calidris alpina, using a key stopover site in Iberia. Plasma triglycerides and β-hydroxybutyrate concentrations did not differ between seasons, and small differences were found in haematological profiles (higher haemoglobin and hematocrit levels in spring). Similar refuelling rates and physiological status suggests a single migratory strategy in spring and autumn. During both seasons, dunlins arrive at the Tagus estuary with medium-to-high fuel loads, indicating they do not engage in prolonged fuelling. This agrees with a skipping migratory strategy, where birds fly short-to-medium distances while fuelling at moderate rates along a network of sites. Although we may expect late spring migrants to experience stronger pressures to optimally schedule migratory events, we found no significant differences in physiological profiles among early, mid and late migrants. Unexpectedly, such differences were found in autumn: early birds showed the highest triglycerides and haemoglobin levels and lowest β-hydroxybutyrate concentrations. These results denote enhanced refuelling rates and blood oxygen-carrying capacity in early autumn migrants, which is typical of jumpers, i.e., birds travelling with larger fuel loads and performing fewer stops. Our study adds substantially to previous knowledge of stopover ecology in migratory shorebirds in the East Atlantic Flyway. Importantly, it indicates that the Tagus estuary is a high-quality stopover site for intermediate fuelling. Yet, understanding non-fuelling stopping functions is needed to ultimately inform conservation planning.