Bird Collisions Research Articles

Influence of rotation speed and frequency on the decision of Columba livia domestica (homing pigeon) to cross the rotor-swept area of paper blades mimicking a wind turbine

Abstract To reduce bird collisions with wind turbines, automatic detection systems have been developed to slow the blades down when a bird is approaching. We experimentally tested whether blade rotational speed (i.e., number of rotations per min) and frequency (i.e., number of times a blade passes a point per min) affected the decision time (i.e., time to take-off), path choice (i.e., the position in the aviary), and decision to cross the rotor-swept area in Columba livia domestica (rock dove [domestic variety]; aka homing pigeon; hereafter, pigeon). We used a homemade device with paper blades, mimicking the movement of wind turbine blades. We adjusted the paper blade dimensions and achromatic contrast with the background to match the visual capabilities of pigeons, increasing the probability of detection. Pigeons were less likely to cross the rotor-swept area at higher speeds and frequencies, independent of their decision time. When pigeons crossed the rotor-swept area (43 out of 160 trials), 63% collided with the blades, regardless of blade speed or frequency. Pigeons chose to avoid the rotor-swept area after they had travel half the distance to the wind turbine. Pigeons were not better able to avoid the rotor-swept area when blades were rotating at low speed and/or frequency and often collided with the blades. Thus, slowing blades to a low rotational speed may not reduce collisions with some species and a complete turbine shutdown may be necessary. The feasibility and economic costs of regular complete shutdowns after the deceleration triggered by the automatic detection systems need further investigation.

Automatic classification of bird species related to power line faults using deep convolution features and ECOC‐SVM model

AbstractBird‐related outages greatly threaten the safety of overhead transmission and distribution lines, while electrocution and collisions of birds with power lines, especially endangered species, are significant environmental concerns. Automatic bird recognition can be helpful to mitigate this contradiction. This paper proposes a method for automatic classification of bird species related to power line faults combining deep convolution features with error‐correcting output codes support vector machine (ECOC‐SVM). An image dataset of about 20 high‐risk and 20 low‐risk bird species was constructed, and the feed‐forward denoising convolutional neural network was used for image preprocessing. The deep convolution features of bird images were extracted by DarkNet‐53, and taken as inputs of the ECOC‐SVM for model training and bird species classification. The gradient‐weighted class activation mapping was used for visual explanations of the model decision region. The experimental results indicate that the average accuracy of the proposed method can reach 94.39%, and its performance was better than other models using different feature extraction networks and classification algorithms.

Risk Assessment of Bird Collisions with a Wind Turbine Based on Flight Parameters

The study addresses the challenge of bird collisions with wind turbines by developing an autonomous risk assessment method. The research uses data from the stereoscopic Bird Protection System (BPS) to anticipate potential collision threats by analysing flight parameters and distance from turbines. The danger factor depends on the flight characteristics of the identified bird species and the parameters of the wind turbine control system. The paper proposes an online quantitative risk assessment model that operates in real time, with the aim of minimising unnecessary turbine shutdowns while improving bird conservation. The model is validated through field data from bird flights. The findings suggest that adaptive management of turbine operations based on real-time bird flight data can significantly reduce collision risks without compromising energy production efficiency. The research underscores the balance between ecological considerations and the economic viability of wind energy, proposing an adaptive strategy that reduces unnecessary turbine stoppages while ensuring the safety of avian species.

Biogeographical patterns in the seasonality of bird collisions with aircraft

Abstract Bird collisions with aircraft pose a serious threat to human safety. However, broad‐scale patterns in how bird strikes might vary through space and time have yet to be fully understood. Here, we conducted a biogeographical study of bird strikes to answer two questions: (1) Are bird strikes higher at certain times of the year in the Northern and Southern Hemispheres? and (2) Is seasonality in bird strikes more prominent in the Northern Hemisphere than in the Southern Hemisphere? To answer these questions, we collated data on monthly bird strikes from 122 airports across the globe and used circular statistics to test for hemispherical asymmetries in the circular mean and variance in bird strikes. Results showed that annual peaks in bird strikes occurred between late summer to autumn seasons, and as a result, they occurred at opposite times of year in the northern and southern hemispheres. Results also showed that bird strikes were more seasonal in the Northern Hemisphere than in the Southern Hemisphere, where strikes tended to occur more consistently throughout the year. Practical implication: Overall results indicate that avian collisions with aircraft show strong biogeographical patterning, concomitant with global patterns in bird breeding seasons and migration tendencies.

Evaluating the impact of bird collision prevention glazing patterns on window views

Optimal design of bird collisions prevention glazing patterns is pivotal in the protection of avian ecology and provision of quality window views for building occupants. However, a research gap currently exists regarding the impact of different pattern designs on the quality of window views. Therefore, this study evaluates the influence of various bird collision prevention pattern designs on window view clarity. A total of 18 patterns, including dot matrix, vertical stripes, and horizontal stripes, were designed and evaluated. The patterns had varying combinations of coverage rates and spacing ratios. Sixty participants were recruited to participate in an experimental survey using virtual reality (VR) technology. They were asked to rate the level of clarity of window views observed through different glazing pattern designs. The results indicated that the bird collision prevention glazing pattern designs significantly influenced occupants’ perception of visual clarity. Designs featuring horizontal and vertical stripes attained higher visual clarity ratings compared to the dot matrix pattern. Additionally, visual clarity significantly decreased with increasing coverage rates and designs with larger spacing ratios were associated with higher clarity than smaller spacing ratios. Most participants were willing to sacrifice window view quality in order to minimize bird fatalities. These findings can guide the development of window view evaluation criteria in existing green building standards, by accounting for the trade-off between avian conservation and window view clarity.

General Comparative Analysis of Bird-Bat Collisions at a Wind Power Plant in the Department of Rivas, Nicaragua, between 2014 and 2022

From 2014 to 2022, eight monitoring campaigns have been carried out, documenting 119 collisions of birds belonging to 25 species corresponding to 14 families. Of the total collisions, 35 individuals could not be identified because only remains of the animal’s body (feathers) were found, due to the presence of day and night predators. Of the bird species identified, 17 are resident, three are migratory species, two are transient species, one species with transient populations that migrate south, and two species with both resident and migratory populations. During these years, no species with an important conservation category according to the IUCN were reported. Three species are on Nicaragua’s Red List, the migratory species Blackburnian Warbler (Setophaga fusca) and the resident species Mangrove Cuckoo (Coccyzus minor), both with the Near Threatened category; and the only migratory hummingbird for Nicaragua, the Ruby-throated Hummingbird (Archilochus colubris) with the Vulnerable category. The family with the highest frequency of collided bird species is the pigeons (Columbidae), these being very significant (X2 = 345.20, p < 0.01). The species with the highest frequency of collisions is the Common Ground-Dove (Columbina passerina) species, with these collisions being very significant (X2 = 72.05, p < 0.01). Collisions per month and year show very significant differences, especially for April 2016 (X2 = 41.60, p < 0.01). Tower T13 shows significant collisions in these eight monitoring campaigns (X2 = 36.48, p < 0.05). Bird collision distances show very significant collisions between 0 and 5 m away from the turbines (X2 = 268.96, p < 0.01). No differences were found regarding collisions between large and small birds (X2 = 2.09, p > 0.05). The granivore group presented a very significant frequency of collisions (X2 = 84.00, p < 0.01), as well as a very significant frequency of collisions in the non-passerines birds (X2 = 42.26, p < 0.01). Very significantly higher fatality frequencies were observed in 2016 (X2 = 60.16, p < 0.01). For the period 2014 to 2022 in bats, 134 collisions of bats belonging to 18 species corresponding to four families were observed. Of the total number of collisions, 24 individuals could not be identified because they were in poor condition. No species with important conservation criteria have been recorded according to the IUCN or the Nicaraguan Red List. The Molossidae family is the group with the highest number of very significant collisions (X2 = 53.61, p < 0.01), with the Pallas’s Mastiff Bat (Molossus molossus) being the one that presented very significant collisions (X2 = 199.69, p < 0.01). Very significant collisions occur, with a peak in November 2015 (X2 = 75.19, p < 0.01). Tower T15 presents the highest frequency of collisions, which is very significant (X2 = 39.04, p < 0.01). The frequency of collisions remains very significantly higher in the three distance categories closest to the towers, from 0 to 14.9 m (X2 = 43.64, p < 0.01). The highest frequency for very significant collisions of bats is that of insectivores (X2 = 222.10, p < 0.01). A very significant frequency of collisions was observed in 2015 (X2 = 68.75, p < 0.01). Key periods like fall and spring bird migration should be prioritized when planning collision monitoring plans. Standardized monitoring protocols and implementation of estimated mortality formulas that compensate for the search effectiveness of observers, the search area, and the removal of collisions are also important for not underestimating bird and bat collisions.

Disentangling the biotic and abiotic drivers of bird-building collisions in a tropical Asian city with ecological niche modeling.

Bird collisions with buildings are responsible for a large number of bird deaths in cities around the world, yet they remain poorly studied outside North America. We conducted one of the first citywide fine-scale and landscape-scale analyses of bird-building collisions in Asia and used maximum entropy modeling (as commonly applied to species distribution modeling) in a novel way to assess the drivers of bird-building collisions in the tropical city-state of Singapore. We combined 7years of community science observations with publicly available building and remote sensing data. Drivers of bird-building collisions varied among taxa. Some migratory taxa had a higher relative collision risk that was linked to areas with high building densities and high levels of nocturnal blue light pollution. Nonmigratory taxa had a higher collision risk in areas near forest cover. Projecting our results onto official long-term land-use plans, we predicted that future increases in bird-building collision risk stemmed from increases in blue light pollution and encroachment of buildings into forested areas and identified 6 potential collision hotspots linked to future developments. Our results suggest that bird-building collision mitigation measures need to account for the different drivers of collision for resident and migratory species and show that combining community science and ecological modeling can be a powerful approach for analyzing bird-building collision data.

Evaluating the potential of bioacoustics in avian migration research by citizen science and weather radar observations.

The study of nocturnal bird migration brings observational challenges because of reduced visibility and observability of birds at night. Remote sensing tools, especially radars, have long been the preferred choice of scientists to study nocturnal migrations. A major downside of these remote sensing tools is the lack of species-level information. With technological advances in recent decades and with improved accessibility and affordability of acoustic tools, sound recordings have steeply increased in popularity. In Europe, there is no exhaustive qualitative and quantitative evaluation of the content of such acoustic databases and therefore the value for migration science and migration-related applications, such as bird collision hazard assessments, is mostly unknown. In the present work we compared migration schedules estimated from citizen science data with quantitative temporal occurrence of species in four years of acoustic recordings. Furthermore, we contrasted acoustic recordings with citizen science observations and weather radar data from one spring and one autumn season to assess the qualitative and quantitative yield of acoustic recordings for migration-related research and applications. Migration intensity estimated from weather radar data correlated best at low levels with acoustic records including all species in spring while in autumn passerine species showed stronger correlation than the entire species composition. Our findings identify a minor number of species whose call records may be eligible for applications derived from acoustics. Especially the highly vocal species Song thrush and Redwing showed relatively good correlations with radar and citizen science migration schedules. Most long-distance passerine migrants and many other migrants were not captured by acoustics and an estimated seasonal average of about 50% of nocturnally migrating passerine populations remained undetected. Overall, the ability of acoustic records to act as a proxy of overall migration dynamics is highly dependent on the migration period and species involved.

To mitigate bird collisions, enforce the Migratory Bird Treaty Act

To mitigate bird collisions, enforce the Migratory Bird Treaty Act

Heavy migration traffic and bad weather are a dangerous combination: Bird collisions in New York City

Abstract Bird–building collisions account for 365–988 million bird fatalities every year in the United States alone. Understanding conditions that heighten collision risk is critical to developing effective strategies for reducing this source of anthropogenic bird mortality. Meteorological factors and regional migration traffic may increase collision rates but also may be difficult to disentangle from other effects. We used 5 years of bird collision counts in New York City to examine the influence of nocturnal weather conditions and bird migration traffic rates on collisions with buildings during spring and fall. We found that seasonally unfavourable winds and conditions that impede visibility are important factors that increase the rates of bird–building collisions during both seasons. Specifically, northerly and westerly winds and low visibility in the spring and southerly and westerly winds and low cloud ceiling height in the fall are associated with higher collision risks. Generally, these weather variables associated most strongly with increased collisions when nocturnal bird migration traffic was high, with the exception of low visibility in spring, which was predicted to triple collision rates compared to high visibility, independent of bird migration traffic. Synthesis and applications: Although legislation to turn off unnecessary nocturnal lighting for the entirety of the migration seasons may be an ultimate goal, a proximate goal invaluable for reducing collisions will be predicting which nights will be of highest risk and using this information to determine when mitigation efforts could be most effective.

Wire marking reduces bird collisions with a transmission powerline in western Belgium

Summary Collisions with powerlines affect birds worldwide, including countries such as Belgium where a nationwide model indicated high avian collision risk in the IJzerbroeken region (seasonally flooded riverside wetlands). Large numbers of waterbirds winter in this area, which is crossed by a 70-kV transmission line. To manage avian collision risk, the transmission system operator, Elia, installed AB Hammarprodukter’s FireFly™ FF line markers incorporating reflective, glow-in-the-dark, high contrast, and moving elements intended to increase the visibility of the transmission line to flying birds. We evaluated the effectiveness of FireFly line markers by comparing the numbers of avian carcasses found during 11 surveys annually in 2001 and 2018 (22 total surveys) before line markers were installed compared with 11 surveys conducted in 2021 after line marking. Before line marking, we found 30 avian carcasses attributable to collision in 2001 and 113 in 2018. After, we found six carcasses attributable to collision in 2021. In 2021, FireFly line markers correlated with a reduction in collision rate, depending on the pre-treatment year and species group, of at least 85% and up to 100%. The line was composed of two configurations, with half of the spans (two-thirds of the monitored line length) supported by tall pylons with shield wires, and half of the spans supported by shorter pylons without shield wires. After line marking, six collisions (100% in 2021) occurred on spans supported by tall pylons, and none (0%) occurred on spans supported by short pylons. Thus, in 2021, FireFly line markers correlated with an observed mortality reduction of at least 73% and up to 100%, depending on the configuration being considered. These findings suggest FireFly line markers substantially reduced wintering bird collisions in our study area.

GPS tracking reveals the timing of collisions with powerlines and fences of three threatened steppe bird species

Summary Collision with powerlines is a major cause of mortality for many bird species, including bustards and sandgrouse. In this work, we used GPS tracking data to identify the hour of collision of three threatened steppe birds, i.e. Little Bustard Tetrax tetrax, Black-bellied Sandgrouse Pterocles orientalis, and Pin-tailed Sandgrouse Pterocles alchata. Out of a data set of 160 GPS-tracked individuals collected over a 13-year period, we detected eight collision events with powerlines or fences. Of these, we were able to determine the timing of 87.5% of the collision events with a resolution accurate to within two hours. Our results reveal that collisions occurred throughout the year and at different hours of the day, presenting a challenge for implementing effective mitigation strategies. The use of dynamic and reflective or luminescent devices may therefore be appropriate to prevent collision of steppe birds with powerlines during the day and night. Overall, this study adds evidence to the utility of using tracking data to better understand anthropogenic mortality in birds.

Novel approach to estimating avian mortality from vehicle–bird collisions on U.S. roads

Novel approach to estimating avian mortality from vehicle–bird collisions on U.S. roads

Bird Collision Prevention Systems in Passenger Aviation

The purpose of this article is to present the results of a preliminary analysis of modern methods for preventing collisions between birds and aircraft. The focus was in particular on methods that enable defining the level of threat in passenger aviation and existing solutions for eliminating these threats. The first section defines the level of the existing threat of collision with birds for civil aviation on the basis of collision statistics based on collision reports submitted by pilots. The second chapter describes normative documents on methods intended to reduce the risk of collisions with birds, such as aviation rules and regulations, passenger aircraft certification, bird detection and deterrence systems, procedures of flight crews and air traffic controllers, and the development of bird detection and deterrence methods. Based on the analysis of existing solutions, the third chapter proposes a block diagram of an on-board system reducing the risk of aircraft collisions with birds by determining the level of collision risk and transmitting information about the risk level to the flight crew in order to reduce the effect of surprise among pilots, improve the accuracy of the statistics and operational safety by carrying out a technical inspection of the aircraft after the collision. The final chapter contains conclusions.

Methodological approaches to assessing population-level impacts of bird collisions with wind turbines: a critical perspective

SummaryWind energy is a source of collision fatalities for birds and bats. To evaluate the risk that wind power development projects might pose to the conservation of protected species, it is essential to quantify the impact of collisions on the dynamics of wild populations. To address this challenge, two approaches are primarily employed: potential biological removal (PBR) and population projection analysis (PPA). PBR is a decision rule designed to calculate a sustainable fatality limit for a given population, whereas PPA relies on simulation-based modelling to forecast a population’s future trajectory under various scenarios. In the context of environmental impact assessments (EIAs), we argue that PPA offers a more suitable method than PBR for evaluating population-level impacts resulting from collisions with wind turbines. Unlike PBR, PPA can be focused on a single source of disturbance, aligning with the perspective of the EIA process. By contrast, PBR necessarily adopts a population-centred perspective and is therefore only relevant when considering all sources of mortality that jointly affect a population. Furthermore, robust utilization of the PBR approach requires the definition of quantitative conservation objectives and the implementation of a comprehensive management strategy evaluation, neither of which is ever undertaken within the context of an EIA.

Estimating mortality of small passerine birds colliding with wind turbines

As demand for renewable energy is rising, wind power development is rapidly growing worldwide. In its wake, conflicts arise over land use changes converting pristine nature into industrial power plants and its associated adverse biodiversity effects, crowned by one of the most obvious and deadly consequences: bird collisions. Most post-construction studies report low levels of avian mortality, but the majority of these studies are conducted primarily on larger birds. However, the diversity and abundance of small passerine birds are rarely reflected in the carcass surveys, although they in numeric proportion to their abundances should be the most numerous. The assumption that surveys find all carcasses seems thus rarely fulfilled and passerine mortality is likely to be grossly underestimated. We therefore designed an experiment with dummy birds to estimate mortality of small-bodied passerines and other small-bodied birds during post-construction surveys, tested in a medium-sized wind farm in western Norway. The wind farm was surveyed weekly during the migration periods by carcass survey teams using trained dogs to find killed birds. The dogs in the carcass surveys were more successful in locating the large than the small dummy birds (60–200 g), where they found 74% of the large dummy birds. Detecting the smaller category (5–24 g) was more demanding and the dogs only found 17% of the small dummy birds. Correcting the post-construction carcass survey outcome with the results from the experiment leads to an almost fourfold increase in estimated mortality rates, largely due to the low detection rate of the smallest category. The detection rates will naturally vary between wind farms, depending on the specific habitat characteristics, the efficiency of the carcass surveys and the search intervals. Thus, implementing a simple experiment with dummy birds to future post-construction surveys will produce more accurate estimates of the wind turbine mortality rates, and thus improve our understanding of the biodiversity effects of conforming to a more sustainable future.

Redesign an aircraft windshield to improve its mechanical resistance against simultaneous bird impacts

The bird impact on aircraft components is one of the most serious accidents which can happen in the aviation industry. Among the various parts of an aircraft, the bird impact on the windshield is more important due to the possibility of causing injury to the pilot. Standard windshields are designed to withstand a bird strike, however, in a group flight of birds, several birds can strike the windshield at the same time. The results of practical tests and simulations show that the current windshields are seriously damaged in the simultaneous collision of several birds and the possibility of birds penetrating the cabin is very high. In this research the mechanical properties of standard windshield constituent materials are obtained. Initially practical tests are carried out and simulation results are verified for single bird strike. Using these results, the simultaneous impact of three birds on a windshield is simulated. It was shown that the resistance of the standard windshield against simultaneous collisions is insufficient. So the thicknesses of the windshield layers are determined in such a way that the new windshield is resistant and bird penetration into the cabin does not happen.

Experimental and numerical investigation on GFRP- aramid honeycomb sandwich panel under bird impact: Estimation of penetration velocity

In order to effectively mitigate the risk of bird strikes, it is imperative that radomes situated in areas prone to such incidents possess the capability to endure the impact loads caused by bird collisions. Additionally, these radomes must maintain their electromagnetic transparency. Therefore, glass fibre reinforced polymer (GFRP) with Nomex honeycomb sandwich material is used for radome structural design. The current research is intended to examine the dynamic behavior of sandwich composite panels in order to determine the penetration velocity by testing them at three distinct bird impact velocities, such as 88 m/s, 135 m/s, and 153 m/s. It is necessary to find the velocity at which the bird will penetrate / rupture the radome for the safety of Antenna / Electronic units mounted behind the radome. Finite element explicit code LS-DYNA simulates all three impacts. Extension of the simulation estimated the threshold bird impact velocity to be 146 m/s at which it penetrates the sandwich panel under fixture-controlled boundary condition.

Mitigation measures for preventing collision of birds with wind turbines

Bird collisions with wind turbines is one of the major environmental impacts of wind energy. To decrease the number of avian fatalities in wind farms, several studies have been done to understand, evaluate and apply measures that reduce the risks of collisions. Overall, mitigation measures during the operational phase of wind farms are based on either active or passive procedures, depending on the need (or not) for an external source to trigger an action for preventing a possible collision. The aim of this work is firstly to provide an overview of mitigation measures that have been demonstrated in-situ, including the overall procedures of the tests, results, as well as advantages and disadvantages of the measures. Subsequently, a new patented control concept to avoid collisions (SKARV) is described. Four measures that have been tested at wind farms in Spain, Norway, and USA are summarized: habitat management and painting (passive measures), turbine curtailment and deterrents (active measures). Estimations from these tests indicate an average reduction of 33%-86% in annual bird fatality for specific targeted species. The SKARV concept is not yet tested, but may be a benign alternative.

Detection of wind turbines rotary motion by birds: A matter of speed and contrast

AbstractTo reduce bird collisions on wind turbines, Automatic Detection Systems have been developed to locate approaching birds and trigger turbines to slowdown to 2–3 rotations per minute (rpm). However, it is unknown whether birds can detect this reduced speed and avoid the turbine. We conducted an operant conditioning experiment on domestic doves (Streptopelia roseogrisea) and Harris's hawks (Parabuteo unicinctus) to assess their ability to discriminate between stationary and rotating miniature wind turbines, depending on the rotation speed and the contrast between the white blades and the background (only for doves for the latter). At high contrast, regardless of the speed tested, hawks were able to differentiate between the rotating and stationary turbines, while doves were not able to discriminate the slow‐rotating turbine (3 rpm) from the stationary one. The discrimination threshold increased to 8 rpm for the doves when the contrast was reduced. Our results suggest that the residual wind turbine speed of 2–3 rpm may not be detected by all bird species under all environmental conditions. Increasing the contrast between wind turbines and their environment may improve the detection of low‐speed rotation by some birds, otherwise, complete turbine shutdown should be recommended.