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Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability
Abstract
Building collisions, and particularly collisions with windows, are a major anthropogenic threat to birds, with rough estimates of between 100 million and 1 billion birds killed annually in the United States. However, no current U.S. estimates are based on systematic analysis of multiple data sources. We reviewed the published literature and acquired unpublished datasets to systematically quantify bird–building collision mortality and species-specific vulnerability. Based on 23 studies, we estimate that between 365 and 988 million birds (median = 599 million) are killed annually by building collisions in the U.S., with roughly 56% of mortality at low-rises, 44% at residences, and <1% at high-rises. Based on >92,000 fatality records, and after controlling for population abundance and range overlap with study sites, we identified several species that are disproportionately vulnerable to collisions at all building types. In addition, several species listed as national Birds of Conservation Concern due to their declining populations were identified to be highly vulnerable to building collisions, including Golden-winged Warbler (Vermivora chrysoptera), Painted Bunting (Passerina ciris), Canada Warbler (Cardellina canadensis), Wood Thrush (Hylocichla mustelina), Kentucky Warbler (Geothlypis formosa), and Worm-eating Warbler (Helmitheros vermivorum). The identification of these five migratory species with geographic ranges limited to eastern and central North America reflects seasonal and regional biases in the currently available building-collision data. Most sampling has occurred during migration and in the eastern U.S. Further research across seasons and in underrepresented regions is needed to reduce this bias. Nonetheless, we provide quantitative evidence to support the conclusion that building collisions are second only to feral and free-ranging pet cats, which are estimated to kill roughly four times as many birds each year, as the largest source of direct human-caused mortality for U.S. birds.
... Research has focused on how these factors influence the risk of bird collision with obstacles , although there are still knowledge gaps regarding low-altitude flights that put birds within range of airspace obstacles (<200 m above ground level). Obstacles present at these altitudes include buildings (365-988 million bird collisions per year; Loss et al. 2014), wind turbines (234,000 bird collisions per year; Loss et al. 2013), and communication towers (4-5 million bird collisions per year; Gehring et al. 2011). Flights at obstacle height can be difficult to study due to blind spots in weather radar at low altitudes (Rogers et al. 2020), although some radar studies have had success in quantifying their prevalence. ...
... We quantified the proportion of simulated flight altitudes that fell below a 120-m threshold, representing the proportion of locations that would not be detectable by weather radar. As low-rise buildings (defined as residential buildings 4-11 stories and nonresidential buildings ≤11 stories) result in the highest number of window collision mortalities in the United States (Loss et al. 2014), we also quantified the proportion of simulated flight altitudes below the height of an 11-story building (47 m). We estimated the proportion of simulated flight altitudes that fell within the rotor-swept zone of the average land-based wind turbine installed in 2022 (32-164 m; Wiser et al. 2023). ...
... These derived metrics are based on altitude data collected using GPS transmitters in the eastern portion of the woodcock's range in 2020-2024. Loss et al. 2014) and a higher rate of mortality associated with birds undergoing stopovers, which can be lengthy and expose birds to mortality risk through the diurnal hours in addition to nocturnal migratory flights (Cusa et al. 2015). In comparison, communication towers kill fewer birds (4-5 million per year) and are less prevalent on the landscape (>26,000 in the USA) but are more likely to result in collisions during migratory flights, especially if guy wires are present (Gehring et al. 2011). ...
Understanding bird migration at low altitudes is critical to evaluating risk of collision with obstacles. Recent advances in satellite tracking technologies allow quantifying use of low altitudes by small migrating birds with a high level of precision, allowing species-level inference into potential collision risk based on flight altitude. Scolopax minor (American Woodcock) is suspected to be a low altitude migrant due to its frequent collisions with buildings, and subsequent mortality during migration may be contributing to population declines. We investigated migratory flight altitudes using satellite transmitters deployed on woodcock in 2020–2024 and examined how flight altitudes compare to the heights of common airspace obstacles. Each transmitter recorded a nocturnal GPS location with an altitude reading every 1–3 days during fall and spring migrations. We implemented a Bayesian hierarchical mixture model to identify whether locations were recorded on the ground or during flight, isolate measurement error, and describe the distribution of flight altitudes. We found that migrating woodcock fly at mean altitudes of 379 m above ground level, flying higher during spring (mean: 444 m, 95% credible interval: 333–578 m) than fall (338 m, 95% CRI: 267–423 m). Woodcock flight altitudes were frequently lower than could be observed using weather radar (27% of observations), and 57% of observations fell within the altitude range of ≥1 airspace obstacle. Our results suggest that woodcock fly at altitudes lower than reported for most nocturnal migrants, which likely contributes to their vulnerability to obstacle collisions. Scolopax minor provide an example of how vulnerability to obstacle collisions during nocturnal migratory flights are often species-specific, and mitigation efforts should incorporate measures aimed at reducing collisions during both diurnal stopovers and nocturnal migratory flights to effectively reduce bird collision mortality.
... Collision with man-made structures is a major conservation issue for migratory songbirds, with between 100 million and 1 billion individuals dying annually from building strikes in the United States alone (Loss et al., 2014). Where songbirds migrate over water, offshore wind turbines and other tall structures pose a collision risk, having many similar characteristics to high-rise buildings, such as height and the presence of artificial lighting (Drewitt & Langston, 2008). ...
... To assess collision vulnerability, we used a published speciesspecific index of vulnerability to collisions with high-rise buildings ( Table 1; Loss et al., 2014). Flight altitude is an important indicator of OSW collision for seabirds; however, this information is uncommonly measured for songbirds migrating across open water. ...
... ,Hartman (1961),Andrews et al. (2009),Gray (2019) andChu et al. (2022). High-rise collision data used to calculate Collision Vulnerability scores were sourced fromLoss et al. (2014). Occurrence data used to calculate Migration Corridor scores were sourced from eBird (https:// ebird. ...
As offshore wind (OSW) energy expands globally, migratory songbirds are at risk of mortality from collisions with turbine blades, though the magnitude of this threat and which species are most vulnerable, remains poorly understood. Ecological vulnerability indices are commonly used to assess species' susceptibility to harmful factors, with results used to direct scarce research and monitoring resources to species showing relatively high vulnerability. These indices are based on the traits that elevate a species risk to adverse impacts (sensitivity), the overlap in occurrence between a species and the potentially harmful agent (exposure) and the influence of this exposure on the species' local or global persistence (resilience).
We modified ecological vulnerability indices for seabirds to assess vulnerability of migratory songbirds to OSW related mortality. As a pertinent case study, we considered songbirds that fly across the Northwest Atlantic during their autumn migration. We utilized readily available information on each species' migratory behaviour, life history, and conservation status to calculate an index score that could range from 1 (lowest vulnerability) to 125 (highest vulnerability).
We found scores of 3 to 55.2 for the 101 songbird species evaluated, with New World warblers (Parulidae) over‐represented among the highest scoring species. We found the scores to be sensitive to uncertainty in index components, highlighting the importance of considering scoring uncertainty when evaluating ecological vulnerability indices. Finally, we found that for seven of the top 10 highest scoring species, modest improvements in population trends had the potential to lower the scores substantially.
Synthesis and applications. Our methodology is readily applicable to other regions where offshore wind (OSW) development is planned and songbird migration is common, allowing research and monitoring activities to be targeted to species most likely to be negatively affected by OSW facility encounters.
... Collisions with buildings are a leading anthropogenic cause of death for birds in the United States [3], with major collision events garnering national attention [4] and, as of 2024, 25 U.S. cities or states have passed legislation that requires new buildings to be bird-friendly [5]. Affecting over 50 avian families and hundreds of species [6]; building collisions kill between 365 million and 1 billion birds a year in the United States alone [7] and pose a significant threat to birds in other countries as well [8][9][10]. ...
... Deadly collisions occur at both multi-story buildings and individual homes and in both urban and rural areas [7,11]. In North America collisions during fall migration typically surpass the other seasons [12][13][14][15]; however, frequent collisions are documented in the spring, summer, and winter months as well [13,[16][17][18][19]. ...
... Most studies examining building collisions are conducted on recovered carcasses of collision victims that die on impact [6,7,15,40]. However, though over 80% of collisions with buildings were once estimated to be immediately fatal to birds [23], more recent studies have not supported this pattern and suggest that far fewer than 80% of collision victims die on site. ...
Building collisions are a leading threat to wild birds; however, only those that are found dead or fatally wounded are included in current mortality estimates, with injured or stunned birds largely assumed to survive long-term. Avian building collision victims are often brought to wildlife rehabilitators for care, with the hopes they can be released and resume their natural lives. We examined the wildlife rehabilitation records of over 3,100 building collisions with 152 different avian species collected across multiple seasons to identify patterns of survival and release among patients. The number of admissions varied by season; fall migration had the highest number of cases and winter had the least number of cases, and summer having the lowest release proportion and winter having the highest. The most common reported injury was head trauma and concussion. Our logistic and Poisson models found that mass had a strong positive effect on release probability, and the season of summer had a strong negative effect on release probability. Mass and winter had a strong positive effect on treatment time, and age and the seasons of fall and winter had a strong negative effect on treatment time in these models. Ultimately, about 60% of patients died in care, either by succumbing to their injuries or by euthanasia. Patients that were released remained in care for longer than patients that died. This study reports different data than carcass studies and views bird-building collisions from the perspective of surviving victims to explore longer-term effects of these collisions on mortality. Increased communication and collaboration between wildlife rehabilitators and conservation researchers is recommended to better understand building collisions and how to respond to this leading threat to wild birds. These findings, along with our estimate of delayed mortality, suggest that overall collision mortality estimates based on carcass collection far exceed one billion birds in the U.S. each year.
... Collisions with buildings and their windows (hereafter "bird-window collisions" or BWCs) are a major cause of avian mortality, annually responsible for up to one billion bird deaths in the US (Loss et al. 2014), tens of millions of deaths in Canada (Machtans et al. 2013), and innumerable deaths world wide (Rebolo Ifrán et al. 2019;Yang et al. 2021). The species most vulnerable to collisions (eg hummingbirds, warblers, thrushes, and sparrows in the western hemisphere) (Loss et al. 2014) receive substantial public and conservation interest due to their declining populations, and to the aesthetic values and ecosystem services they provide to society (Whelan et al. 2015). ...
... Collisions with buildings and their windows (hereafter "bird-window collisions" or BWCs) are a major cause of avian mortality, annually responsible for up to one billion bird deaths in the US (Loss et al. 2014), tens of millions of deaths in Canada (Machtans et al. 2013), and innumerable deaths world wide (Rebolo Ifrán et al. 2019;Yang et al. 2021). The species most vulnerable to collisions (eg hummingbirds, warblers, thrushes, and sparrows in the western hemisphere) (Loss et al. 2014) receive substantial public and conservation interest due to their declining populations, and to the aesthetic values and ecosystem services they provide to society (Whelan et al. 2015). Reflecting the critical importance of this issue, reducing BWC occurrence has been recognized as one of seven simple actions that can help stem the decline of North America's avifauna (www.3bill ...
... Research has increased greatly over the past few decades, and in this recent era of BWC science, studies have identified species groups most prone to collisions and factors that increase collision risk. Information about BWCs remains sparse outside North America, but studies in the US and Canada have shown that collisions tend to peak in spring and fall and primarily impact migratory species, especially nocturnal migrants (Loss et al. 2014). However, large numbers of BWCs also can occur outside of migration periods, especially when food resources that attract birds (eg bird feeders, fruiting plants) are located near buildings (Ocampo Peñuela et al. 2016;Brown et al. 2019). ...
Citizen science use in gathering data on bird-window collisions in multiple countries to help in global conservation.
... It has been argued (Shochat et al., 2004;Evans et al., 2015) that lower survival due to urbanization mainly results from top-down processes like higher rates of predation (Bonnington, Gaston, & Evans, 2013; but see Fischer et al., 2012) or collisions with manmade objects (Loss et al., 2019), whereas higher survival results from bottom-up processes like higher resource availability (Shochat et al., 2004). This suggests that for the chiffchaff, European robin and European greenfincheach experiencing survival costs in urban areastop-down processes play a relatively more important role. ...
... Whilst this can account for our findings of high mortality of robins and greenfinches in urban areas, other typical ground-dwellers in our dataset like common blackbirds, dunnocks and house sparrows did not conform this pattern. Another major source of avian mortality in urban areas is bird-building collision (Loss et al., 2014;Pavisse, Vangeluwe, & Clergeau, 2019). Although building-collision has been shown to affect species during migration most (Loss et al., 2014;Wittig et al., 2017), local foliage gleaning species are also susceptible (Wittig et al., 2017). ...
... Another major source of avian mortality in urban areas is bird-building collision (Loss et al., 2014;Pavisse, Vangeluwe, & Clergeau, 2019). Although building-collision has been shown to affect species during migration most (Loss et al., 2014;Wittig et al., 2017), local foliage gleaning species are also susceptible (Wittig et al., 2017). While such species are represented in our dataset too (great tit, blue tit, Eurasian blackcap, common chiffchaff), and buildingcollisions likely contribute to mortality, we cannot directly link it to patterns in our results. ...
Urbanization forms one of the most drastic alterations of the environment and poses a major threat to wildlife. The human–induced modifications of the landscape may affect individual's fitness resulting in population declines. Research on how urbanization affects fitness traits has shown mixed results. However, studies typically contrasted data from a single species from few urban and non‐urban sites collected over short timeframes. Examining multiple species across a broad urbanization gradient enables a more robust comparison and understanding of how different species are impacted by urbanization‐knowledge crucial for generating population predictions, which are essential for conservation management. Here, we use data from a nation‐wide citizen science project to examine variation in survival and relative body mass and size (wing length) of common passerine birds, collected along an urbanization gradient in the Netherlands over an 8‐year period. Urbanization was measured as the distance from the city's border and the proportion of impervious surface area. Although the overall association between urbanization and survival was slightly negative, there was support for lower survival closer to the city in three species (chiffchaff Phylloscopus collybita, European robin Erithacus rubecula, European greenfinch Chloris chloris) and higher survival closer to the city in two (great tit Parus major and house sparrow Passer domesticus) of the 11 species examined. The contrasting survival successes among species suggest that ongoing urbanization may lead to shifts in community structure and loss of biodiversity. Impacts of urbanization on relative mass and size also exhibited varying effects, albeit less pronounced, and these effects were not correlated with the effects on survival. This implies that body mass and size cannot be used as indicators for urban‐associated patterns of survival. Our results further imply that effective conservation management targeting bird communities should involve a range of diverse actions, as focusing on single measures is unlikely to simultaneously impact multiple species due to the variation in responses to urbanization.
... Apesar do conhecimento rudimentar (Chace & Walsh 2006), hoje sabemos que a urbanização afeta a biodiversidade. Além disso, alguns dos fatores comuns nas áreas urbanas que afetam a biodiversidade como: 1) o aumento do calor (Brans et al. 2017;Izuddin et al. 2019;Johnson et al. 2019;Moll et al. 2019;Varquez & Kanda 2018;Yang et al. 2017;Yu et al. 2018), 2) o aumento do ruído (carros, aviões, residências etc.) (Alquezar et al. 2020; Barbosa et al. 2020;Castaneda et Welbers et al. 2017;Xue et al. 2020;Zheng et al. 2021), 4) o aumento da poluição (Antonini et al. 2013;Bailly et al. 2017;Bauerová et al. 2017a;Cid et al. 2018;Soares et al. 2003;Yauk et al. 2000), 5) a alteração dos recursos alimentares (Chace & Walsh 2006;De León et al. 2019;Galbraith et al. 2017;Luna et al. 2021;Miyasaki et al. 2017;Murray et al. 2018;Navarro et al. 2021b;Pollock et al. 2017;Saufi et al. 2020;Zietsman et al. 2019), 6) a introdução de novos predadores (Alexandrino et al. 2019;Baker et al. 2005;Blancher 2013;Bonnaud et al. 2012;Bradshaw et al. 1999;Calver et al. 2011;Castañeda et al. 2020;Krauze-Gryz et al. 2017Krauze-Gryz et al. 2012;Luna et al. 2021;Turner & Bateson 2014), 7) o impacto decorrente de colisões (aviões, carros, vidros) (Allan 2006;Allan et al. 2016;Brown et al. 2021;Carter 2001;Elmore et al. 2021;Klem 2021;Loss et al. 2014;Marchini & Crawshaw 2015;Riding et al. 2021;Zakrajsek & Bissonette 2005;Zalakevicius 2000), e 8) o aumento de doenças (Bradley & Altizer 2007;Gibb et al. 2020;Giraudeau et al. 2014a;Sándor et al. 2017;Zuo et al. 2018). Apesar disso, são necessários mais estudos para permitir um entendimento adequado da relação biodiversidadeurbanização. ...
... Apesar disso, alguns efeitos diretos da urbanização sobre a fauna, relatados ao redor do mundo, são bem visíveis: mortes de aves devido à colisão com vidros (Brown et al. 2021;Elmore et al. 2021;Loss et al. 2014;Zyśk-Gorczyńska et al. 2020), predação de ninhos de aves por gatos-domésticos (Baker et al. 2005;Blancher 2013;Bonnaud et al. 2012;Calver et al. 2011;Krauze-Gryz et al. 2017;Marzluff et al. 2015) e redução de polinizadores (Tzortzakaki et al. 2019). Em contrapartida, efeitos menos diretos foram também avaliados e são importantes como: alteração das condições corporais e prevalência de parasitas (Jiménez-Peñuela et al. 2019), respostas imunológicas devido à poluição (Baesse et al. 2019;Fenger 1999) (Sandakova et al. 2018;Suárez-Rodríguez et al. 2013), as áreas urbanas aparentam oferecer condições desfavoráveis aos animais silvestres. ...
Paisagens urbanas são cada vez mais dominantes ao redor do mundo criando uma nova interface para a fauna silvestre. Apesar de ter sido ignorado por muito tempo pelos ecólogos, o entendimento dos processos em áreas urbanas recebe crescente atenção para a construção de um arcabouço atual de desenvolvimento sustentável e conservação da biodiversidade. Assim, é preciso explorar de forma detalhada como as diferentes características de áreas urbanas filtram espécies e selecionam
características da fauna silvestre. Neste sentido, esta tese se propôs, utilizando espécies de aves silvestres no Distrito Federal (DF) como um modelo, a estudar a relação da expansão e intensificação urbana. O objetivo geral foi investigar as assembleias de aves urbanas e sua relação com o processo de urbanização. Pretendo entender como a urbanização afeta os indivíduos que nela persistem, avaliando sua morfologia, saúde e o uso dos recursos alimentares. Também discorro sobre adaptações metodológicas realizadas em decorrência das dificuldades da amostragem de aves nos ambientes urbanos. A tese está estruturada em oito capítulos interligados pelo tipo de ambiente explorado durante o estudo: ambientes urbanos. Esses capítulos utilizam diferentes abordagens e tem distintos objetivos. Apesar disso, todo o direcionamento do trabalho está focado nos impactos que a urbanização provoca na fauna em seus diferentes aspectos (em nível de comunidade ou de população) e os determinantes ambientais relevantes para os animais que nela vivem. Além disso, em alguns capítulos abordo questões metodológicas, tendo em vista as dificuldades de amostragem de aves nos ambientes urbanos. Por último, apresento um capítulo compilando o conhecimento atual sobre os ambientes urbanos em forma de um texto de divulgação científica para a população, que incorpora meus achados nos ambientes urbanos de Brasília. Meus resultados mostram que as áreas urbanas impactam de forma direta as aves, tanto em nível de comunidade como em nível das populações. Em nível de comunidades, observei clara redução da diversidade (taxonômica, filogenética e funcional) e mudança da estrutura da comunidade em área com maior intensidade urbana. Em nível d populações, observei um aumento da proliferação de doenças (lesões nas patas), aumento do estresse crônico (razão H/L), e mudanças morfológicas e alimentares. Esses achados confirmam minha hipótese inicial de que as áreas urbanas promovem pressões significativas sobre as espécies, afetando
os animais que nela persistem. Meus achados são relevantes pois o entendimento de como as espécies lidam com as pressões ambientais causadas pelas modificações urbanas podem ajudar gestores a tornar as cidades mais amigáveis à fauna, principalmente quando pensamos nos desafios globais de manutenção das populações nativas que estão em declínio.
... Las aves se enfrentan a diversas amenazas en áreas urbanas, que incluyen la depredación por gatos domésticos (Loss et al., 2015), contaminación ambiental por metales pesados como plomo, cadmio y arsénico (De Luca-Abbott et al., 2001;Markman et al., 2011), envenenamiento (Orlowski et al., 2010) y las colisiones con cables de alta tensión, vehículos motorizados, molinos de viento y ventanales de edificios (Klem, 1990;Hager et al., 2008;Loss et al., 2014;Gómez-Moreno et al., 2018). ...
... El problema de colisión con ventanas está ocasionando una tasa de mortalidad que oscila entre los 3,5 hasta 42 millones de aves por año en Estados Unidos de América y Canadá (Klem, 1990;Drewitt y Langston, 2008;Loss et al., 2014). El valor es aún mayor si consideramos la mortalidad de aves que se genera a causa de las colisiones en las áreas urbanas de toda Latinoamérica. ...
Las colisiones con ventanas causan millones de muertes de aves al año, estos eventos se deben a que estas son incapaces de reco-nocer el vidrio como una barrera física. En algunos estudios se menciona que existen familias y comportamientos que hacen que algunas especies sean más susceptibles a chocar. Los objetivos del presente estudio fueron determinar la composición de especies que colisionan contra las ventanas de los edificios, conocer la cristalería que genera mayor grado de mortalidad y analizar las ca-racterísticas de las especies como hábitos migratorios, alimenticios y estados de conservación de las especies afectadas. El estudio se llevó a cabo en Ciudad Victoria, Tamaulipas, México. Donde fueron seleccionadas tres áreas con edificios que presentaran la mayor cantidad de cristalería y se estuvieron monitoreando tres veces de enero a diciembre de 2019. Se obtuvieron 270 cadáveres pertenecientes a 44 especies, de estas Zenaida asiática (Linnaeus,1758) fue la de mayor número de accidentes, la cristalería reflec-tante generó una elevada tasa de mortalidad y cada estación del año es distinta en cuanto a la composición de aves afectadas. Estas estructuras están generando un declive en especies con estatus de conservación (Passerina ciris Linnaeus, 1758) y endemis-mos de México (Corvus imparatus Peters, JL 1929 y Periporphyrus celaeno Deppe, W 1830). Los hallazgos evidencian un problema para la conservación de especies y, por esta razón, se debería continuar investigando los edificios para conocer el impacto real que se está ocasionando en las poblaciones de aves
... Researchers have estimated effects of some human-related sources of direct bird mortality (Banks 1979, Erickson et al. 2005, Loss et al. 2015. According to a summary compiled by USFWS (2023), the largest direct source of bird mortality is predation by cats, estimated to cause 1.3-3.7 billion deaths per year (Loss et al. 2013b), followed by collisions with buildings (365-988 million; Loss et al. 2014a) and collisions with vehicles (89-340 million; Loss et al. 2014b). The USFWS is the federal agency responsible for protecting much of the country's fauna and flora and associated habitats (USFWS 2024). ...
... Our driving data also undersampled some of the USFWS regions, which could lead to bias (of unknown direction) in our estimate. Our estimate is consistent with others that put vehicles as one of the top three sources of bird mortality, yet less than the combined 365 million-3.7 billion casualty range estimated for building collisions and cat predation (Loss et al. 2013b(Loss et al. , 2014a. All three continental USA VBC estimates are greater than those attributed to commercial infrastructure, including electrical lines, communication towers, oil pits, and wind energy turbines (Trail 2006, Longcore et al. 2012, Loss et al. 2013a, 2014c, Erickson et al. 2014. ...
... Many migratory species encounter anthropogenic structures while moving across landscapes. Interactions with some of these (e.g., roads, buildings, wind turbines, hydropower dams) may cause immediate injury or mortality, thereby having direct consequences for populations (Keefer et al. 2012;Beebee 2013;Loss et al. 2014;Frick et al. 2017). While direct mortality is the most obvious risk imposed by human infrastructures, indirect consequences may also affect populations. ...
Reservoir predation has been identified as a leading mortality source for smolts migrating through impounded river systems. We investigated smolt predation risk for an endangered Atlantic salmon (Salmo salar) population in the Weldon Dam reservoir in the Penobscot River, Maine, USA. In spring 2022, we characterized the fates of 390 tethered smolts. Smolts were exclusively predated by two predator species not native to the study area: chain pickerel (Esox niger, n = 43) and smallmouth bass (Micropterus dolomieu, n = 42). Using Cox-proportional hazard analysis, we estimated that 23% (95% CI = 15%–29%) of tethered smolts were expected to be predated within a one-hour deployment. Water temperature was the primary driver of predation risk as predation probability increased from 10% to 33% when temperature increased from 5 to 15 °C. Smolts also incurred above-average predation risk when they were within 40 m of shore. We demonstrate that non-native fish predation may drive patterns of high impoundment mortality and that risk is spatially and temporally heterogeneous within these systems. Collectively, this study offers direct evidence of species-specific predation on Atlantic salmon smolts and illuminates potential strategies to mitigate predation risk during reservoir migration.
... Zu beiden Aspekten gibt es viele, zum Teil dramatische Bilanzen in globalen bis regionalen Skalen (z. B. Loss et al. 2013Loss et al. , 2014 und dementsprechend eine Fülle von Empfehlungen und Handreichungen zur Minderung der Probleme (z. B. Rössler et al. 2022). ...
... It is well known that illuminated offshore structures, such as lighthouses, light vessels, oil and gas platforms, and bright ships and research platforms, attract nightmigrating birds, increasing their collision risk (e.g., Hüppop et al., 2006Wiese et al., 2001;Figures 2 and 3), which is considered one of the key mortality threats (Loss et al., 2014). Reliable estimates of collision events with offshore structures are challenging to obtain due to several factors: the difficulty of accessing remote sea locations, the low probability of detecting collision carcasses in the water at these structures, and the technical limitations for unbiased and continuous recording of collisions and monitoring their aftereffects (Molis et al., 2019). ...
Human activity in the North Sea is intensifying, as emerging uses, such as offshore wind farms (OWFs) and liquid natural gas (LNG) terminals, are added to fishing, freight shipping, and fossil fuel production as traditional forms of resource exploitation. The volume and scale of these additional installations are projected to increase substantially in the coming decades, which amplifies the need to better understand the biological implications of human activities in the ecoregion. Previous studies have identified that offshore wind turbines either pose a physical barrier to flying animals, leading to avoidance and displacements, or act as ecological traps by interfering with sensory input, leading to increased attraction, collision risk, and mortality. Here we aim to characterize the impacts of marine artificial light pollution at night (ALAN) on offshore migratory birds and bats and discuss implications for conservation policy and practice. Considering littoral states aim to multiply the OWF capacity by a factor of eight before the year 2050, a significant increase in the cumulative impacts of ALAN can be expected. In light of these developments, we discuss the potential for scientifically informed, anticipatory, and ecosystem‐based marine governance.
... Similarly, many pressing global landcover changes, such as urbanization, occur at fine scales that require high spatial resolution to properly investigate in an ecological context (Cadenasso et al. 2007). From a conservation standpoint, there is growing evidence that collisions with human-built structures are a major source of mortality (Loss et al. 2014) and the amount of anthropogenic light at night can influence migrant behavior, attracting and trapping birds in brightly lit areas . Near-term forecasting of migration events has already demonstrated immense value to conservation practitioners and is often used to inform Lights Out campaigns across the United States, which seek to reduce anthropogenic light during periods of intense migration (Burt et al. 2023). ...
Our ability to forecast the spatial and temporal patterns of ecological processes at continental scales has drastically improved over the past decade. Yet, predicting ecological patterns at broad scales while capturing fine-scale processes is a central challenge of ecological forecasting given the inherent tension between grain and extent, whereby enhancing one often diminishes the other. We leveraged 10 years of terrestrial and atmospheric data (2012–2021) to develop a high-resolution (2.9 × 2.9 km), radar-driven bird migration forecast model for a highly active region of the Mississippi flyway. Based on the suite of candidate models we examined, adding terrestrial predictors improved model performance only marginally, whereas spatially distant atmospheric predictors, particularly air temperature and wind speed from focal and distant regions, were major contributors to our top model, explaining 56% of variation in regional migration activity. Among terrestrial predictors, which ranked considerably lower than atmospheric predictors in terms of variable importance, vegetation phenology, artificial light at night, and percent of forest cover were the most important predictors. Furthermore, we scale this model to demonstrate the capacity to generate real-time, high-resolution forecasts for the continental United States that explained up to 65% of national variation. Our study demonstrates an approach for increasing the resolution of migration forecasts, which could facilitate the integration of radar with other data sources and inform dynamic conservation efforts at a local scale that is more relevant to threats, such as anthropogenic light at night.
... Participatory research strategies (i.e., those that involve stakeholders) allow projects to engage diverse audiences and understand the perspectives of stakeholders from multiple levels and multiple organizations, and more effectively solve complex problems (Cornwall and Jewkes 1995;Vaughn and Jacquez 2020). Projects involving volunteers as stakeholders can collect data more efficiently, provide educational opportunities 1 It is recommended that collision surveying be frequent, consistent, and long-term so variations across days, weeks, and seasons can be accounted for (American Bird Conservancy 2020;Brown et al. 2021;Loss et al. 2014). Ideally, surveys should be completed for at least 18 months at least once per day as collisions often occur in the morning hours and carcasses can be quickly scavenged or collected by building maintenance staff (American Bird Conservancy 2020). ...
Bird populations face many threats worldwide, including collisions with anthropogenic structures such as buildings’ windows. Bird-window collisions are gaining attention, but research and mitigation often face barriers including collision surveying guidelines, funding availability, and retrofitting costs and approvals. Beginning in 2022, we conducted research about bird-window collisions on an urban university campus to engage students in research and inform the implementation of mitigation at the site(s) with the most collisions. To achieve these goals, we worked with undergraduate and graduate students, faculty, staff, administrators, and media personnel to monitor bird-window collisions, spread the word throughout the community, and advocate for retrofitting buildings. Research was incorporated into a course-based undergraduate research experience, several undergraduate directed studies, paid undergraduate research positions, and volunteer opportunities. By the end of 2024, bird-friendly window markers were installed on two buildings on campus. In this article, we present the collective reflections and lessons learned from university stakeholders involved in the project. We recommend that similar conservation projects on university campuses (1) maximize project flexibility and consider how to best support stakeholders; (2) build impact and momentum over time by engaging stakeholders in unique ways; and (3) leverage participants’ previous experiences and use a solution-focused approach to ensure that participation is motivating and rewarding. With our lessons learned, similar projects on other university campuses may be able to attain more success in student engagement, project outcomes, and ultimately, the implementation of bird-friendly practices.
... Altered movement patterns Potential for habitat fracturing and altered home ranges [75,80] Mortality Mortality events due to "lake effect" collisions or solar flux [67,[85][86][87][88][89][90] Altered species composition Changes in both species diversity and functional diversity for regions [94,[96][97][98] While the data for avian and solar farm interactions are limited, studies have examined other forms of human disturbance and bird interactions. Bird-window collisions are an increasingly common occurrence in the United States, with an estimated 100 million to upwards of 1 billion deaths/year [99]. Birds are not able to recognize the reflective and transparent glass surfaces as barriers to their movement, leading to collisions [100]. ...
Given the threat of climate change caused by greenhouse gas emissions, climate-safe alternatives are receiving more attention. One of the most widespread solutions is the implementation of solar-powered technologies. These technologies, once implemented, do not increase emissions and provide safe, clean energy sources. However, large-scale solar farms require large amounts of land space in areas that receive increased sunlight to operate successfully. As such, there have been proposals to establish solar farms adjacent to or encroaching on wetland habitats. Currently, little is known about the interactions between wildlife, specifically waterbirds, and solar installations in wild areas, specifically wetland environments. In this article, we examine the current knowledge base of wildlife interactions with solar infrastructure in natural environments. We highlight a significant need for more information on wetland ecosystems and the responses of migratory water-fowl that are dependent on these ecosystems. Finally, we present methods of mitigation to reduce the occurrence of these interactions and future considerations for research. While solar facilities represent an opportunity to decrease the reliance on fossil fuels, care must be taken so that their installation does not harm local ecosystems.
... However, data from the citizen science website Urubu System (Sistema Urubu, 2022) demonstrates that from 2014 to 2022, over 13,000 bird roadkill records have been registered on Brazilian highways, affecting 410 species. Statistics for window collisions in Brazil are not available, but it is believed that the mortality rate is as high as in other countries, such as the United States, where bird mortality is estimated at 100 million to one billion annually (Loss et al., 2014). ...
Birds with craniocephalic trauma (CET) show clinical signs such lack of proprioception, hypothermia, altered respiratory rates, fractures, and potential blindness. Treatment focuses on life support, including low-stimulus environments, analgesia, anti-inflammatory drugs, fracture immobilization, and patient stabilization through warmth, oxygenation, hydration, and soft food. Recovery time is uncertain, often resulting in death within days. Factors influencing recovery include injury severity, species size, treatment speed, presence of other diseases, and stress levels. We analyzed the species and their characteristics, occurrences periods, and outcomes of 265 birds of 60 species with CET received at the Wildlife Study Group at the University of Passo Fundo (GEAS-UPF) between 2015-2023. Most cases (72%) succumbed to death on average three days after admission, with small-sized birds having the highest mortality rate (86%). Passeriformes and Strigiformes were the most frequent orders, and the predator guild was the most affected.
... A interferência humana, tanto direta quanto indireta, adiciona riscos significativos às aves migratórias. A poluição ambiental, a colisão com estruturas como torres eólicas e edifícios envidraçados, e o impacto do tráfego aéreo são problemas críticos que afetam a sobrevivência das aves (Loss et al., 2014;Buehler et al., 2007). Essas ameaças não só reduzem as taxas de sobrevivência, mas também comprometem as rotas migratórias e os locais de parada essenciais. ...
Entre céu e mar: a migração das aves nas praias de São Paulo é uma obra que vai
além da simples observação; ela eleva essa prática a uma verdadeira arte, uma forma de conexão profunda com o mundo natural. Para aqueles que desejam não apenas ver, mas compreender, esta obra se torna uma necessidade, uma janela aberta para o entendimento das complexas interações entre as aves migratórias e os ambientes que atravessam. Sob a orientação e o vasto conhecimento do Professor Doutor Edison Barbieri, este livro oferece mais do que informações; oferece uma imersão total no encanto e na vida dessas aves, muitas das quais permanecem um mistério para a maioria das pessoas.
Cada página deste livro é uma porta de entrada para desvendar os mistérios e
apreciar a incrível diversidade dessas aves, que dividem conosco as praias e os céus do nosso amado estado de São Paulo. Através de descrições detalhadas, ilustrações ricas e uma narrativa envolvente, você será guiado por uma jornada que celebra não apenas a beleza das aves, mas também a complexidade da natureza que as sustenta.
Esta obra é mais do que um simples registro científico; é uma celebração vibrante da
beleza e da complexidade do mundo natural, um tributo às aves que, ano após ano,
desafiam distâncias inimagináveis, cruzando céus e mares em uma demonstração de pura sobrevivência e adaptação.
Ao mergulhar neste livro, você não apenas aprenderá sobre essas magníficas criaturas, mas também será convidado a refletir sobre o delicado equilíbrio que
mantém essas migrações, sobre os desafios que essas aves enfrentam em um
mundo em constante mudança, e sobre o papel que todos nós desempenhamos
na preservação de suas rotas e habitats. Venha conosco nessa jornada e permita-se ser encantado por este espetáculo da vida, onde cada voo, cada canto e cada
pouso revelam a história de resiliência, beleza e conexão que as aves migratórias
compartilham com todos nós.
... Trees that bear fruit may attract more birds and increase their local abundance, as well as their risk of colliding with glass on nearby buildings [2]. Since buildings frequently do not have vegetation surrounding their entire perimeter, in studying bird collisions, facades with vegetation in the vicinity can be concentrated on [10,11]. ...
The characteristics of building surroundings can influence the number of bird deaths caused by collisions with glass structures. Thus, this study investigated whether the number of trees, the distance to the nearest tree, the number of fruit trees, and the glass area influenced the number of bird collisions on a university campus in Brazil from March 2017 (breeding and non-breeding seasons) to January 2018 (breeding season). Twenty-four birds died due to collisions with the windows in the one-year sampling. Among the factors evaluated, the number of trees and the area of the glass predicted the number of deaths from collisions. The greater the number of trees and the glass area, the greater the number of bird collisions. This suggests that the more vegetation there is near windows, the more birds are attracted, and the less visible the glass barrier becomes, possibly due to the appearance of trees in reflections or scenes viewed through the glass, making it difficult for birds to distinguish the real landscape from the reflected environment. If large expanses of glass are placed on buildings near vegetation, including trees, more bird collisions will occur. Thus, to reduce bird collisions, building designs should reduce the amount of glass used on building exteriors near vegetation and ensure the glass is treated with visual markers.
... Man-made structures, such as urban buildings, present both challenges and opportunities for avian breeding. On the one hand, buildings can disrupt flight paths, leading to increased mortality from collisions (Loss et al., 2014), and can indirectly affect breeding success in proximate fragmented natural habitats (Hedblom & Söderström, 2012). On the other hand, these human-altered landscapes offer novel nesting opportunities for many bird species, supporting a range of nesting behaviors ( Figure 1) (Mainwaring, 2015). ...
... Furthermore, we investigated how extracting information from OSM compares to the information provided by commonly used remote-sensing landscape characterization products in ecological studies. For this, we focused on the "buildings" class, an intrinsic infrastructure of urban areas that impacts wildlife movement and survival (Loss et al. 2014). Building footprints are the polygons delimiting each singular building on the land and can also be used to estimate building density and, along with roads, can be used to estimate impervious surface area, both landscape predictors commonly used in urban ecology (Haight et al. 2023). ...
Wildlife abundance and movement are strongly impacted by landscape heterogeneity, especially in cities which are among the world's most heterogeneous landscapes. Nonetheless, current global land cover maps, which are used as a basis for large‐scale spatial ecological modeling, represent urban areas as a single, homogeneous, class. This often requires urban ecologists to rely on geographic resources from local governments, which are not comparable between cities and are not available in underserved countries, limiting the spatial scale at which urban conservation issues can be tackled. The recent expansion of community‐based geographic databases, for example, OpenStreetMap (OSM), represents an opportunity for ecologists to generate large‐scale maps geared toward their specific research needs. However, computational differences in language and format, and the high diversity of information within, limit the access to these data. We provide a framework, using R, to extract geographic features from the OSM database, classify, and integrate them into global land cover maps. The framework includes an exhaustive list of OSM features describing urban and peri‐urban landscapes and is validated by quantifying the completeness of the OSM features characterized, and the accuracy of its final output in 34 cities in North America. We portray its application as the basis for generating landscape variables for ecological analysis by using the OSM‐enhanced map to generate an urbanization index, and subsequently analyze the spatial occupancy of six mammals throughout Chicago, Illinois, USA. The OSM features characterized had high completeness values for impervious land cover classes (50%–100%). The final output, the OSM‐enhance map, provided an 89% accurate representation of the landscape at 30m resolution. The OSM‐derived urbanization index outperformed other global spatial data layers in the spatial occupancy analysis and concurred with previously seen local response trends, whereby lagomorphs and squirrels responded positively to urbanization, while skunks, raccoons, opossums, and deer responded negatively. This study provides a roadmap for ecologists to leverage the fine resolution of open‐source geographic databases and apply it to spatial modeling by generating research‐specific landscape variables. As our occupancy results show, using context‐specific maps can improve modeling outputs and reduce uncertainty, especially when trying to understand anthropogenic impacts on wildlife populations.
... We quantified the proportion of woodcock flight locations (represented by the posterior of ( , )) which fell below a 120m threshold, which we used to represent the proportion of locations would not be detectable by weather radar. As low-rise buildings (defined as residential buildings 4-11 stories and non-residential buildings ≤11 stories) result in the majority of window collision mortalities in the United States (Loss et al. 2014), we also quantified the proportion of locations at an altitude below that of an 11-story low-rise building (47m). We also estimated the proportion of woodcock flight locations which fell within the rotor sweep of the average land-based wind turbine installed in 2022 (32-164m; Wiser et al. 2023). ...
The widespread availability of satellite tracking devices has made it possible to track
individual migratory birds throughout the full annual cycle, examining how distribution and habitat use change between seasons and regions while also describing the characteristics of migratory movements. We used these devices to examine the full annual cycle ecology of American Woodcock (Scolopax minor; hereinafter woodcock), an early successional habitat specialist whose populations are declining throughout their range in eastern North America. We used these data to develop a multi-season distribution model for woodcock management in Pennsylvania, demonstrating the importance of considering habitat use across multiple seasons for migratory bird conservation. We also used woodcock migratory movements to demonstrate improved methods for classifying animal locations into migratory states, allowing inferences into migratory behavior despite sparse and incomplete data. We examined changes in woodcock habitat selection among seasons, finding that woodcock likely undergo a functional response in their habitat selection to changes in habitat availability throughout the full annual cycle. Finally, we described woodcock flight altitudes and their corresponding vulnerability to various airspace obstacles, finding that low altitude
flights are likely a contributing factor to woodcocks’ disproportionate collisions with
buildings. Stabilizing woodcock populations will likely require better understanding of
woodcock ecology throughout the full annual cycle, as well as the threats they face at each stage. We hope that our comprehensive analysis of woodcock distribution, habitat use, and migration ecology throughout the full annual cycle will improve conservation of this iconic upland bird species.
... High GDP also has a negative impact on bird diversity-the higher the GDP, the higher the level of economicization of the region, which also implies high regional urbanization. In addition, we also found that building height has a negative impact on bird diversity, possibly due to the fact that taller buildings are often associated with higher pedestrian and automobile traffic [42], and both traffic and high-rise buildings have been reported to be major anthropogenic threats, often resulting in a range of negative impacts, such as a high frequency of bird strikes [6,[43][44][45]. ...
Urban ecological corridors play an important role in facilitating bird migration and maintaining biodiversity in urban landscapes as key connections between habitat patches. However, the effects of built environment characteristics of urban ecological corridors on bird diversity have not been well understood. In this study, we used Minhang District, Shanghai, as an example to describe the built environment of urban ecological corridors through three dimensions (habitat characteristics, degree of surrounding urbanization, and degree of slow-traffic connectivity). We calculated species richness, abundance, Shannon–Wiener index, and Simpson Index to assess bird diversity based on the bird observation dataset from the Citizen Science Data Sharing Platform. The effects of built environment characteristics of urban ecological corridors on bird diversity were quantified by the Generalized Linear Model. The results showed that: (1) There were significant differences in the built environment characteristics of urban ecological corridors, which formed the spatial differentiation pattern of bird diversity. (2) Different built environment features of urban ecological corridors have different impacts on bird diversity. Habitat suitability of urban ecological corridors was positively correlated with bird diversity, with birds preferring to inhabit waters with an area of more than 1 ha. The degree of urbanization was negatively correlated with bird diversity, with distance to the center of the area proving to have the strongest positive effect. The degree of slow-traffic connectivity proved that low-intensity human activities in urban ecological corridors had a lower impact on bird diversity. The above findings can provide scientific reference for the construction of urban and regional ecological networks in the future.
... T he global demand for electricity in the last few decades has promoted a rapid deployment of power line networks (IRENA, 2017). Worldwide, tens of millions of birds die annually due to power lines (Scott et al., 2014), and it has long been recognized as one of the most important negative impacts associated with overhead transmission and distribution systems (Bevanger, 1994;Lehman et al., 2007;Bernardino et al., 2018). Importantly, several studies have argued that overhead power lines and their support structures may increase the local bird diversity, especially in treeless landscapes or in intensive agricultural landscapes, as they provide alternative nesting, resting, and perching sites (Tryjanowski et al., 2004(Tryjanowski et al., , 2014Mainwaring, 2015). ...
... T he global demand for electricity in the last few decades has promoted a rapid deployment of power line networks (IRENA, 2017). Worldwide, tens of millions of birds die annually due to power lines (Scott et al., 2014), and it has long been recognized as one of the most important negative impacts associated with overhead transmission and distribution systems (Bevanger, 1994;Lehman et al., 2007;Bernardino et al., 2018). Importantly, several studies have argued that overhead power lines and their support structures may increase the local bird diversity, especially in treeless landscapes or in intensive agricultural landscapes, as they provide alternative nesting, resting, and perching sites (Tryjanowski et al., 2004(Tryjanowski et al., , 2014Mainwaring, 2015). ...
... For example, a common practice involves the installation of transparent noise barriers along roads with bird silhouettes to prevent bird collisions, typically conducted retrospectively. However, bird fatalities resulting from collisions with transparent surfaces have been largely documented, with identifiable occurrences [57]. This further substantiates the necessity for accurate, multi-step decision-making processes, as discussed in Section 5. ...
The paper examines the integration of novel Transportation Ecology principles into transit operations, aiming to address the environmental impacts associated with surface services in urban areas and with the purpose of creating a comprehensive agenda for integrating ecological principles into transit planning and management. The research problem is to quantify the tangible benefits for transit operators, particularly in the context of mitigating wildlife-vehicle collisions and improving overall operational efficiency as a motivator for transit managers to adopt Transportation Ecology principles. The study design, after analyzing the regulatory requirements, implements scenario-based methodology, utilizing data from an average Italian bus fleet to estimate potential monetary savings and benefits. Key parameters, such as maintenance costs, insurance premiums, and collision-related expenses, are analyzed to provide a realistic assessment of the economic advantages of implementing Transportation Ecology measures. The findings reveal that significant cost reductions can be achieved by minimizing accidents involving wildlife, alongside other operational improvements. The scenario demonstrates that even a small fleet, when adopting these principles, can yield substantial financial benefits, thereby making a compelling case for broader implementation. The paper concludes that while the qualitative nature of the analysis necessitates conservative estimates, the results underscore the value of incorporating ecological considerations into transit planning and management. These insights are vital for transit operators and policymakers seeking to balance environmental sustainability with operational profitability and protect urban ecosystems. This also implies the need for a more holistic and interdisciplinary approach to transportation planning and management.
... Bird collisions with multistoried buildings and intense light at nighttime in urban centers are significant mortality factors causing billions of bird deaths worldwide annually (Klem Jr, 2009;Loss et al., 2019). Windows are the primary cause of bird collisions, resulting in the deaths of an estimated 365-988 million birds annually in the United States (Loss et al., 2014) and 16-42 million birds annually in Canada . Birds collide with windows when they either do not recognize transparent glass or mistake reflections of the sky or surrounding habitat in the glass for real scenery thus resulting either injury or mortality (Bayne et al., 2012;Lao et al., 2023). ...
... Bird collisions with multistoried buildings and intense light at nighttime in urban centers are significant mortality factors causing billions of bird deaths worldwide annually (Klem Jr, 2009;Loss et al., 2019). Windows are the primary cause of bird collisions, resulting in the deaths of an estimated 365-988 million birds annually in the United States (Loss et al., 2014) and 16-42 million birds annually in Canada . Birds collide with windows when they either do not recognize transparent glass or mistake reflections of the sky or surrounding habitat in the glass for real scenery thus resulting either injury or mortality (Bayne et al., 2012;Lao et al., 2023). ...
... Bird collisions with multistoried buildings and intense light at nighttime in urban centers are significant mortality factors causing billions of bird deaths worldwide annually (Klem Jr, 2009;Loss et al., 2019). Windows are the primary cause of bird collisions, resulting in the deaths of an estimated 365-988 million birds annually in the United States (Loss et al., 2014) and 16-42 million birds annually in Canada . Birds collide with windows when they either do not recognize transparent glass or mistake reflections of the sky or surrounding habitat in the glass for real scenery thus resulting either injury or mortality (Bayne et al., 2012;Lao et al., 2023). ...
... Molded to our physical constitution and its capacities, many of these spaces are not just unaccommodating to animals; they are hostile, even deadly. To take one example: In the United States alone, almost one billion birds will collide into glass windows every year (Loss et al. 2014). Incapable of discerning their mirrored surfaces from open sky, they crash into the urban world we take for granted. ...
... The growing number of smooth surfaces such as glass windows and solar panels can introduce serious problems for wildlife. A major cause of avian mortality is the impact of collision with glass buildings (Klem, 1990;Loss et al., 2014;Santos, De Abreu, & De Vasconcelos, 2017). Smooth surfaces can also reflect polarized light, and hence aquatic insects often mistake smooth surfaces for water bodies due to their similar light polarization patterns, consequently causing maladaptive reproductive behaviours such as egg-laying over solar panels (Malik et al., 2008;Horváth et al., 2009Horváth et al., , 2010. ...
The amount of artificial smooth surfaces in the environment increases continuously with urbanization on a global scale. There is growing evidence that smooth surfaces such as windows, solar panels and other objects can serve as sensory traps for many animal species. Artificial smooth surfaces can function as acoustic mirrors, disrupting echolocation of bats and consequently causing maladaptive behaviours such as drinking from and colliding with these surfaces. Therefore, investigating opportunities to mitigate the effects of artificial smooth surfaces is important from a conservation viewpoint. Here, we conducted a field experiment with bats, an ensonification experiment in the laboratory, and a computer simulation, in order to study the effect of mechanical surface modification on the acoustic characteristics of smooth surfaces. In the field experiment, we presented a horizontal smooth plate alone or with strings (diameters between 0.25–2.5 mm) and the behaviour of bats around the plate was video recorded. Bats significantly decreased the frequency of drinking events with increasing diameter of the strings. We also found an indication that a crossed pattern of the strings on the plate may be more effective than a parallel arrangement. The results of the ensonification experiment and the mathematical modelling revealed that a subtle modification of the smooth surfaces with long, linear thin objects can effectively modify the acoustic characteristics of smooth surfaces in general and thereby potentially change the behaviour of bats. Further investigations from sensory, behavioural and ecological viewpoints are proposed to better understand the impact of smooth surfaces on bats and the mitigation solutions that are needed. This research underscores the significance of exploring innovative approaches to minimize the negative impacts of urbanization on wildlife, highlighting the potential of practical interventions to promote coexistence between anthropogenic environments and threatened species.
... harvest, poaching, utilization for medicine or pets) and unintentionally (e.g. vehicle and building strikes, poisons and toxins; Cunningham et al., 2022;Darimont et al., 2023;Loss et al., 2014;Nakayama et al., 2019). The diverse means by which humans kill, remove, or extract animals have made humans a formidable lethal force across ecosystems (Darimont et al., 2015). ...
Human activities catalyse risk avoidance behaviours in wildlife across taxa and systems. However, the broader ecological significance of human‐induced risk perception remains unclear, with a limited understanding of how phenotypic responses scale up to affect population or community dynamics. We present a framework informed by predator–prey ecology to predict the occurrence of non‐consumptive effects (NCE) and trait‐mediated indirect effects (TMIE) of anthropogenic disturbances. We report evidence from a comprehensive review of the different types of human‐induced behavioural and physiological phenotypic changes and their influence on vital rates and population parameters in wildlife. Evidence for human‐induced NCEs and TMIEs is mixed, with half of published studies finding a relationship between human activities, phenotypic change and population outcomes. The net effects of anthropogenic NCEs and TMIEs depend on the mismatch between the phenotypic response and the lethality of human activity. However, strong research biases in taxa, systems, human disturbance types and demographic measures prevent unified inference about the prevalence of population responses to human activities. Coexistence with and conservation of wildlife requires additional research linking human‐induced phenotypic change to population and community outcomes.
... Furthermore, numerous studies from other flyways have demonstrated the negative impacts of light pollution on migratory birds, including disorientation, improper habitat selection, and fatal collisions (Horton et al. 2023;McLaren et al. 2018;Van Doren et al. 2017;Winger et al. 2019), the latter worsened by the high densities of buildings with glass exteriors in urban centres (Cusa et al. 2015;Loss et al. 2014). Although data are not yet widely available for the EAAF (Shi et al. 2022), these impacts are likely applicable to birds on this flyway. ...
Migratory birds are experiencing widespread population declines, underscoring the urgency of effective conservation actions. Long-term monitoring of migratory birds, especially during migration, is crucial for such actions yet remains technically challenging. Bioacoustic monitoring of nocturnal flight calls (NFCs) constitutes a promising technique to monitor migratory birds during migration. Such monitoring has increased in North America and Europe, but its application on the East Asian–Australasian Flyway (EAAF) remains limited. Here, we present findings from an NFC monitoring project conducted at a recording station in central Beijing, China over four migration seasons. From around 3,350 hours of recording effort, we manually extracted and identified 84,135 NFCs, involving at least 111 species or species groups that are associated with a wide range of habitat types. We also found that NFCs provided additional information on species’ migration phenology in comparison with citizen science observation data. To our knowledge, this study is the first formal investigation of bird migration using NFC monitoring on the EAAF, serving as a proof-of-concept case for wider, long-term monitoring efforts in this traditionally understudied region. Our findings also highlight the significance of incorporating migratory bird conservation into urban planning and land management practices.
... It is well known that illuminated offshore structures attract night migrating birds (phototaxis) increasing collision risk (Ballasus et al. 2009, Rebke et al 2019. For migratory birds, collision is considered one of the key mortality threats (Loss et al. 2014). Offshore collisions with illuminated structures are mainly reported from lighthouses and light-vessels as well as oil and gas platforms, brightly illuminated ships and research platforms (e.g. ...
Human activity in the North Sea is intensifying, as emerging uses, such as offshore wind farms (OWFs) and liquid natural gas (LNG) terminals, are added to fishing, freight shipping and fossil fuel production as traditional forms of resource exploitation. The volume and scale of these additional installations are projected to increase substantially in the coming decades, which amplifies the need to understand better the biological implications of human activities in the ecoregion. Previous studies have identified that offshore wind turbines either pose a physical barrier to flying animals, leading to avoidance and displacements, or act as sensory traps attracting animals by interfering with the sensory input of natural cues, leading to increased collision risk and mortality. Here we aim to characterise impacts of artificial light pollution at night (ALAN) on offshore migratory birds and bats, and discuss implications for conservation policy and practice. Considering littoral states are aiming to multiply the OWF capacity by a factor of eight before the year 2050, a significant increase in the cumulative risk increase of ALAN can be expected. In light of these developments, we discuss the potential for scientifically informed, anticipatory and ecosystem-based marine governance.
... Explaining why certain species choose to use urban areas, and how they manage to thrive in these habitats while others are unable to do so, is essential for fully understanding humans' impact on wildlife. While it is evident that some species, such as foxes (Vulpes vulpes) and raccoons (Procyon lotor), fare better in urban areas than they do in rural ones (Chace and Walsh, 2006;Bateman and Fleming, 2012), urbanisation is generally associated with negative consequences for wild animals, such as greater exposure to toxicants and parasites (Murray et al., 2019), fatal collisions with buildings (Loss et al., 2014) and trafficinduced mortality (Glista et al., 2008). Furthermore, species that use urban areas are sometimes considered a nuisance due to unwanted interactions with humans, creating conflict between prioritising human wellbeing and preserving wildlife (Lyytimäki et al., 2008;Barrett et al., 2019). ...
The expansion of urban areas affects wild animals in a variety of ways. Why members of closely-related species respond differently to urbanisation is often unclear, but an understanding of the factors that lead to urban habitat use or avoidance will have important implications for conservation. Previous research has suggested that urban habitats could favour larger-brained, behaviourally flexible species, which can more readily cope with the novel challenges imposed by urbanisation. However, the opportunity species have to colonise urban areas, and similarities between urban areas and species’ natural habitats, may also explain urban habitat use. We use phylogenetic path analysis to investigate factors that could promote urban breeding and foraging in the gull subfamily, a group with several urbanised species. While we find little evidence to support a relationship between brain size and urban foraging, we reveal an indirect relationship between brain size and urban breeding: cliff-nesting species have relatively larger brains and these species are more likely to breed in urban areas. We show that cliff nesting in gulls is a derived trait and may therefore reflect plasticity in breeding habitat choice, facilitating the use of buildings as nesting sites. Finally, we show that urbanised gull species are less likely to be of international conservation concern or decreasing in population size, exposing the need for more research on the causes and consequences of urban habitat use.
Bird strikes have become a critical concern in aviation safety. This study employed CiteSpace, leveraging bibliometric methods, to conduct a scientometric analysis of 1,885 peer-reviewed articles from the Web of Science Core Collection, offering a structured knowledge map in the field. Through collaborative analysis, it became evident that the leading edge of bird strike research is predominantly performed in the United States, England, China, Germany, Australia, and Canada. These nations serve as hubs for active authors and institutions, and the research reports emanating from these regions constitute the bedrock of knowledge in this specialised domain. Research endeavors are converging predominantly on six thematic clusters: fan blade, airport, damage mechanics, bird migration, bird strike, and maternal investment. A detailed evolutionary analysis of co-occurring keywords was undertaken to identify and track the most recent research trends. This study highlights four future research directions: advancing numerical simulation and crashworthiness, enhancing wildlife management strategies, addressing bird strike challenges in developing countries, and fostering interdisciplinary collaboration for policy development. By providing a structured knowledge map, this research informs policymakers and aviation professionals, offering practical insights for enhancing aviation safety and guiding future exploration.
Predicting animal movements and spatial distributions is crucial for our comprehension of ecological processes and provides key evidence for conserving and managing populations, species and ecosystems. Notwithstanding considerable progress in movement ecology in recent decades, developing robust predictions for rapidly changing environments remains challenging.
To accurately predict the effects of anthropogenic change, it is important to first identify the defining features of human‐modified environments and their consequences on the drivers of animal movement. We review and discuss these features within the movement ecology framework, describing relationships between external environment, internal state, navigation and motion capacity.
Developing robust predictions under novel situations requires models moving beyond purely correlative approaches to a dynamical systems perspective. This requires increased mechanistic modelling, using functional parameters derived from first principles of animal movement and decision‐making. Theory and empirical observations should be better integrated by using experimental approaches. Models should be fitted to new and historic data gathered across a wide range of contrasting environmental conditions. We need therefore a targeted and supervised approach to data collection, increasing the range of studied taxa and carefully considering issues of scale and bias, and mechanistic modelling. Thus, we caution against the indiscriminate non‐supervised use of citizen science data, AI and machine learning models.
We highlight the challenges and opportunities of incorporating movement predictions into management actions and policy. Rewilding and translocation schemes offer exciting opportunities to collect data from novel environments, enabling tests of model predictions across varied contexts and scales. Adaptive management frameworks in particular, based on a stepwise iterative process, including predictions and refinements, provide exciting opportunities of mutual benefit to movement ecology and conservation.
In conclusion, movement ecology is on the verge of transforming from a descriptive to a predictive science. This is a timely progression, given that robust predictions under rapidly changing environmental conditions are now more urgently needed than ever for evidence‐based management and policy decisions. Our key aim now is not to describe the existing data as well as possible, but rather to understand the underlying mechanisms and develop models with reliable predictive ability in novel situations.
Seabird populations are declining rapidly due to numerous anthropogenic threats, including habitat destruction, invasive species, longline fisheries bycatch, and plastic ingestion. However, few studies have investigated seabird collisions with anthropogenic structures, and those studies have primarily focused on a particular taxon or location. Little research has addressed seabird collisions with buildings and similar structures despite bird-building collisions being a major source of mortality for other groups of birds in coastal and inland areas. We conducted an analysis of seabird collisions using band recovery data spanning from 1930 to 2023 from the North American Bird Banding Program, focusing on records categorized as: “caught due to striking: stationary object other than wires or towers.” Our objective was to describe taxonomic and spatiotemporal patterns emerging from these collision records, information that can be used to identify research needs and make recommendations for monitoring seabird collisions. There were 407 records of 39 seabird species representing 13 families that were categorized as striking buildings or similar structures. Species in Laridae (gulls and terns) and Pelecanidae (pelicans) represented 80% of records; Diomedeidae (albatrosses) was the only other family representing more than 5% of records. Band recoveries of collision victims were concentrated in the eastern United States, southern Canada, and urban areas on the West Coast of the U.S. and Canada. Over half of records (n = 228) were from ocean coastlines, with fewer from inland (n = 146) and offshore locations (n = 30). Most records (~90%) had no information about the type of structure with which the bird collided, but observer remarks indicate that seabirds collided with buildings, offshore oil platforms, docks/piers, and even boats. Elucidating and mitigating impacts of collisions with structures on seabird populations requires increased collision monitoring at coastal and offshore structures, which are highly underrepresented in this dataset and are likely a significant threat to seabirds. There is also a need for formal mechanisms for reporting seabird fatalities that account for sampling and detection-related biases and that allow observers to report specific structure types.
Human activities have profound impacts on ecological systems and biodiversity worldwide. Estimating wildlife response to those activities across broad spatial scales is challenging, yet effective conservation measures require an understanding of where and when these activities are contributing to population declines. We investigated the relationship between exposure to human activities (conservation challenges) and population trends of migratory warblers (Parulidae) that breed in the United States and Canada. Our four‐stage approach (1) summarizes the literature describing the sensitivity of species to conservation challenges; (2) estimates weekly species' exposure across the full annual cycle; (3) quantifies spatial correlations among species' exposure to conservation challenges; and (4) quantifies the relationships between seasonal exposure to conservation challenges and warbler population trends. Exposure during post‐breeding migration, followed by the stationary non‐breeding season and pre‐breeding migration, explained the most variation in warbler population trends. Within the post‐breeding migratory season, the conservation challenges with the greatest total seasonal exposure values were roads, light pollution, communication towers, forest management, and livestock management. During this season, species undergoing the steepest declines were associated with exposure to light pollution, communication towers, urban and suburban areas, livestock management, and agriculture. Notably, exposure to conservation challenges during the breeding season was not an important predictor of warbler population trends. Our results provide hemispheric, full annual cycle information for prioritizing conservation investments and additional research for warblers, specifically the importance of addressing challenges to which birds are exposed during post‐breeding migration. More broadly, this framework can be used to assess spatiotemporal conservation challenges impacting migratory species trends globally.
Las colisiones de aves contra ventanas son responsables por mil millones de muertes de aves anualmente en los Estados Unidos, y son la segunda mayor causa de muertes de aves causadas por humanos. Aunque las ventanas pueden ser una amenaza significativa para las aves Neotropicales, pocos estudios han cuantificado este problema y ninguno se ha enfocado en residencias en esta región tropical. Investigaciones en los Estados Unidos y Canadá muestran que las residencias son responsables por 44% y 90% de las colisiones contra ventanas, respectivamente. Nosotros estudiamos colisiones de aves contra ventanas en una residencia rural en una reserva natural de 4 hectáreas ubicada en el piedemonte de los Andes Orientales de Colombia. Grandes y abundantes ventanas proveían excelentes vistas pero también causaban colisiones frecuentemente, muchas de las cuales fueron fatales. Entre el 2009 y el 2012 probamos el efecto de calcomanías en la reducción de colisiones. Seguido a la aplicación de calcomanías en cinco ventanas (0.41 calcomanías/m2) las colisiones se redujeron en un 84%. Aquí presentamos un caso exitoso de prevención de colisiones de aves contra ventanas en una escala de hogar para inspirar a otros a prevenir la mortalidad aviar.
Seasonal migration is highly labile from an evolutionary perspective and known to rapidly evolve in response to selective pressures. However, long‐distance migratory birds rely partially on innate genetic programs and may be constrained in their ability to alter their migratory behavior. We take advantage of recent advances in our ability to genotype historical DNA samples to examine the temporal stability of migratory connections between breeding and nonbreeding populations (i.e. migratory connectivity) and population‐level nonbreeding distributions in the Wilson's warbler Cardellina pusilla, a long‐distance migratory songbird. By assigning historical and contemporary samples collected across the nonbreeding range to genetically distinct breeding clusters, we suggest that broad‐scale population‐level nonbreeding distributions within this species have remained largely consistent within Mexico from the mid‐1900s to the present day. These findings support the idea that the nonbreeding distributions of long‐distance migrants may remain stable over long time scales, even in the face of rapid environmental change.
Keys to Field Sparrow (Spizella pusilla) management include providing shrub-dominated edge habitat adjacent to grasslands or grasslands with a shrub component (both of which must include dense grass and moderately high litter cover) and avoiding disturbances that eliminate woody vegetation. Field Sparrows have been reported to use habitats with 16–134 centimeters (cm) vegetation height, 20–145 cm visual obstruction reading, 17–90 percent grass cover, 2–45 percent forb cover, less than 63 percent shrub cover, 3–7 percent bare ground, 14–30 percent litter cover, and 1–7 cm litter depth.
Bird–window collisions are a leading source of bird mortality worldwide, estimated to kill as many as 1 billion birds annually in the U.S. alone. Though researchers have examined the factors contributing to general bird–window collisions, shadow-boxing, a nonfatal but potentially ecologically significant bird–window interaction, has primarily been excluded from the conversation. Shadow-boxing occurs when birds attack their reflection in human-made surfaces believing the reflection to be another individual intruding on their territory. Current bird–window interaction research often does not consider the unique drivers, impacts, and mitigation strategies associated with shadow-boxing. In this paper, we identify 5 major knowledge gaps: (1) building and environmental characteristics that lead to shadow-boxing; (2) the impacts on individual birds, (3) populations, and (4) people; and (5) the effectiveness of existing mitigation strategies for shadow-boxing. For each knowledge gap, we list research questions that will further our understanding of the scale and significance of shadow-boxing.
In this chapter, we deal with the following sources and case studies of polarized light pollution (PLP): Tree resin as the most ancient PLP source: polarotactic aquatic insects fossilized in amber. Car surfaces and solar panels. How white orthogonal grid lines reduce PLP. PLP of lamplit bridges for night-swarming polarotactic mayflies. Asphalt roads versus polarotactic mayflies and stoneflies. Dragonflies and damselflies as victims of PLP. Impact of a huge oil spill on horseflies. Polarization-based ecological traps for aquatic insects. Atypical feeding of birds on mass-swarming polarotactic caddisflies attracted to glass panes. Hypothetic role of polarization of glass-reflected light in bird-building collisions.
Collisions between wild birds and anthropogenic structures, such as window panes, pose a significant threat, resulting in an alarming number of bird deaths annually. Despite being a global concern, scientific research in Latin America remains incipient, highlighting the need for more research into the impacts on birdlife. In this study, we collected and examined 46 carcasses of 23 bird species that collided with glass structures on a university campus in Sorocaba, SP, Brazil, from March 2017 to June 2023, as part of regular local monitoring of bird collisions and windows. The carcasses were analyzed using necropsy procedures and x-rays, to understand the physical damage caused by these accidents. The species with the largest number of samples were Columbina talpacoti (9 individuals) and Turdus leucomelas (5 individuals). The findings revealed fractures in several bones, bruises and cranial hemorrhages as the main injuries of these collisions. This preliminary assessment not only contributes to the limited existing knowledge, but also highlights the urgency of addressing bird-window collisions to mitigate their detrimental effects on birds.
El objetivo de este texto es analizar algunas cualidades relevantes de los mecanismos (o sistemas) existentes en la naturaleza y las amplias posibilidades
de aplicación al mundo artificial a través de la biomímesis, para permitir al ser humano resolver diferentes necesidades, problemas y requerimientos. Se analizarán algunos casos representativos de mecanismos de seres vivos, también se expondrán casos de biomímesis, estos se han seleccionado porque ejemplifican las
amplias posibilidades de artificialización.
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.
An annotated bibliography of empirical studies that contribute to an understanding of when, how, why, and where most bird collisions (primarily bird-window collisions) occur, and that offer practical solutions.
Predation by house cats (Felis catus) is one of the largest human-related sources of mortality for wild birds in the United States and elsewhere, and has been implicated in extinctions and population declines of several species. However, relatively little is known about this topic in Canada. The objectives of this study were to provide plausible estimates for the number of birds killed by house cats in Canada, identify information that would help improve those estimates, and identify species potentially vulnerable to population impacts.
In total, cats are estimated to kill between 100 and 350 million birds per year in Canada (> 95% of estimates were in this range), with the majority likely to be killed by feral cats. This range of estimates is based on surveys indicating that Canadians own about 8.5 million pet cats, a rough approximation of 1.4 to 4.2 million feral cats, and literature values of predation rates from studies conducted elsewhere. Reliability of the total kill estimate would be improved most by better knowledge of feral cat numbers and diet in Canada, though any data on birds killed by cats in Canada would be helpful.
These estimates suggest that 2-7% of birds in southern Canada are killed by cats per year. Even at the low end, predation by house cats is probably the largest human-related source of bird mortality in Canada. Many species of birds are potentially vulnerable to at least local population impacts in southern Canada, by virtue of nesting or feeding on or near ground level, and habitat choices that bring them into contact with human-dominated landscapes where cats are abundant. Because cat predation is likely to remain a primary source of bird mortality in Canada for some time, this issue needs more scientific attention in Canada.
Context
Increasingly, ornithologists are being asked to identify major sources of avian mortality so as to identify conservation priorities.
Aims
Considerable evidence suggests that windows of office towers are a lethal hazard for migrating birds. The factors influencing the risk of bird–window collisions in residential settings are not understood as well.
Methods
Citizen scientists were requested to participate in an online survey that asked about characteristics concerning their homes and yards, general demographic information about participants, and whether they had observed evidence of bird–window collisions at their home.
Key results
We found that 39.0% of 1458 participants observed a bird–window collision in the previous year. The mean number of reported collisions was 1.7 ± 4.6 per residence per year, with 38% of collisions resulting in a mortality.
Conclusions
Collisions were not random, with the highest collision and mortality rates at rural residences, with bird feeders > rural residences without feeders > urban residences with feeders > urban residences without feeders > apartments. At urban houses, the age of neighbourhood was a significant predictor of collision rates, with newer neighbourhoods reporting fewer collisions than older neighbourhoods. Most people remembered collisions occurring in the summer months.
Implications
Our results are consistent with past research, suggesting that window collisions with residential homes are an important source of mortality for birds. However, we found large variation in the frequency of collisions at different types of residences. Proper stratification of residence type is crucial to getting accurate estimates of bird–window collisions when scaling local data into larger-scale mortality estimates.
Collisions of birds with windows were studied by reviewing the literature, collecting data from museums and individuals, monitoring man-made structures, and conducting field experiments. Approximately 25% (225/917) of the avian species in the United States and Canada have been documented striking windows. Sex, age, or residency status have little influence on vulnerability to collision. There is no season, time of day, and almost no weather condition during which birds elude the window hazard. Collisions occur at windows of various sizes, heights, and orientations in urban, suburban, and rural environments. Analyses of experimental results and observations under a multitude of conditions suggest that birds hit windows because they fail to recognize clear or reflective glass panes as barriers. Avian, manmade structural, or environmental features that increase the density of birds near windows can account for strike rates at specific locations. A combination of interacting factors must be considered to explain strike frequency at any particular impact site. The earliest account of a bird hitting a window in North America is by Nuttall (1832:88). He described a Sharp-shinned Hawk (Accipiter striatus) which, in the pursuit of prey, flew through two panes of greenhouse glass only to be stopped by a third. Townsend (1931) described a series of five fatalities of the Yellow-billed Cuckoo (Coccyzus americanus). His paper was the first to suggest that avian vulnerability to windows may be more marked in some species than in others and that specific windows claim a succession of victims. He termed the victims "tragedies" and apparently regarded them as rare, self-destroying incompetents. Picture windows were relatively uncommon through the end of World War II, and there was little reason for concern about their threat to birds. In the postwar period, a building boom stimulated the rapid expansion of the sheet glass industry, and large glass windows were incorporated into the designs of new and remodeled structures. Today, it is not uncommon to find modern buildings that are entirely surfaced with glass. I found 88 papers reporting bird-window collisions, primarily after the mid-1940s (Klein 1979). They document strikes in North America, South America, West Indies, Europe, and Africa, and, with few exceptions are cited in annotated bibliographies on man-caused mortality to birds (Weir 1976, Avery et al. 1980). However, most textbooks and encyclopedia treatments of ornithology present little, if any, description of the fatal hazards that windows pose to birds. The sheet glass industry and its commercial allies appear to be unaware of the problem. On the other hand, I found avian fatalities resulting from window strikes to be common knowledge among the general public. Birds have been reported to strike two general types of windows as classified according to their visual effects on the human eye. These are transparent windows which appear invisible and reflective windows which mirror the facing outside habitat. Two general types of collisions have been described (Wallace and Mahan 1975:456) and both reveal the ability of glass to misinform and misguide at least some birds. One primarily involves birds such as Northern Cardinal (Cardinalis cardinalis) that commonly flutter against picture windows and harmlessly peck the glass during the spring and summer. These birds seldom, if ever, stun or injure themselves or shatter the glass and usually are males defending their territories against their reflected images. In the second type, birds fly into transparent or reflective windows as if unaware of their presence. These collisions often have fatal consequences, and are the subject of this paper. In this paper my objectives are: (1) to propose an explanation for why birds collide with windows, (2) to describe and analyze species, environmental and manmade structural characteristics associated with bird-window collisions in the United States and Canada, and (3) to suggest how these select characteristics account for the differential frequency with which birds strike windows in various man-made structures.
Most migratory songbirds are nocturnal migrants, which makes them vulnerable to collision with lighted structures they encounter along their flight path during migration. The Fatal Light Awareness Program (FLAP) was formed by a group of concerned citizens to rescue and relocate disoriented birds trapped in the city centre, and to record the number and species of birds killed due to collision. Following the initiation of the Bird Friendly Building (BFB) Program by FLAP and World Wildlife Fund Canada in 1997, light emissions at 16 buildings in the downtown core of Toronto were also monitored during migration seasons. This report summarizes data on birds and light emissions collected from 1997 to spring 2001. This data provides evidence that: • the number of fatal bird collisions increases with increasing light emissions • the number of birds entrapped by particular buildings rises with increasing light emissions • the BFB has been successful in reducing light emissions • weather is the most important factor influencing collision risk • nights of heavy cloud cover and/or nights with precipitation are the conditions most likely to result in high numbers of collisions. A survey of building managers involved in the BFB program revealed that tenant education programs about bird collisions had increased awareness of the problem. Managers found that most tenants were willing to participate in the BFB, which they saw as a “green” initiative that had a positive environmental impact. Many buildings had installed or reprogrammed automated light systems that reduced the number of night-time hours that lights were left on. Several buildings that had limited success in reducing light levels between 1997 and fall 2001 have recently installed automated timer systems that should dramatically improve their light emission reductions in the future. In general, the BFB represents a win-win situation for property managers because reducing the period of time that lights are on not only reduces bird mortality but also results in substantial cost savings due to reduced energy consumption. An estimated $3.2 million could be saved if all of the 16 monitored buildings employed the nighttime light emission reductions already in place at several of the BFB sites. Such a reduction in power consumption would result in an estimated reduction of 38,400 tons of CO2-emissions from fossil-fuel burning energy sources. The BFB therefore contributes locally to a reduction in bird mortality, and globally to a reduction in carbon dioxide emissions, thus reducing the production of greenhouse gases that lead to global climate change.
Mortality from birds colliding with windows in buildings may be ecologically significant. Although data are
sparse, we estimated the number of birds killed by this means in Canada. We made distinct models for three classes of buildings: houses, low-rise commercial and institutional buildings, and tall buildings. Estimates were developed using Monte Carlo-based simulations incorporating uncertainties and based on distributions that best fit available data or conceptual models. We estimate that about 25 million (range 16 – 42 M) birds are killed by colliding with windows in Canada annually. The assumptions used in our analyses are identified in detail so that subsequent efforts can address the uncertainties. Houses likely cause 90% of
building-related mortalities, low-rise buildings slightly less than 10%, and tall buildings approximately 1%. The disproportionate contribution of mortality caused by houses is a function of their relative number compared to the two other classes of buildings. Our review found that warblers and sparrows were the most commonly killed birds at low-rise and tall buildings, and insufficient information exists on species deaths at houses to determine proportions. Targeted mitigation for certain tall buildings and a segment of the low-rise building types could significantly reduce the total mortality for both these building types. Mitigation strategies are now widely available, including architectural guidance produced by numerous cities in North America as well as specific products suitable for home use to reduce the number of birds colliding with windows.
A Migrating birds congregate near the shores of Lake Erie during migration and may be funneled through small green spaces within the urban matrix of Great Lake coastal cities, where they are at risk of higher mortality from manmade structures. Bird deaths due to window collisions were assessed amongst a complex of low-rise buildings (<30 m) on a university campus in Cleveland, OH. A 1.8 km route was surveyed three times per week during a 12-month period. Deaths were tested against null hypotheses that season, taxonomy, and building attributes had no signicant relationship with avian mortality. We recovered 271 dead birds of 50 species, all of which were consistent with regional bird lists and Neotropical-Nearctic and North American migrants through Ohio. Deaths occurred non-randomly by week, month, and migratory status with 90 percent of deaths occurring during spring and fall migrations. Consequently, migrants (warblers: 34 percent of species richness, 30 percent of deaths; sparrows: 14 percent of richness, 35 percent of deaths) were observed nine times more frequently than residents. Neotropical-Nearctic migrant species outnumbered North American migrant species. Although there was no statistical dierence between the compass direction of a building facade and the number of deaths, deaths were not randomly distributed among campus buildings. Rather, signicantly more deaths occurred at facades with higher percentages of glass. e presence of trees within 5 m of a window and the reection of trees in windows were also associated with a greater risk of fatality. A better understanding of the factors associated with bird-window collisions is a pressing issue in the conservation of migratory birds.
Bird strikes were recorded at the windows of commercial and private buildings to study the effects of collision mortality on birds, and several experiments were conducted to evaluate methods of preventing collisions between birds and glass panes. Two single houses that were systematically monitored annually killed 33 and 26 birds, respectively. Collisions at one house in the same 4-mo period (September- December) in consecutive years resulted in 26 and 15 fatalities, respectively. At least one out of every two birds were killed striking the windows of these single dwellings. The records from these homes also revealed that window strikes are equally lethal for small and large species. The annual mortality resulting from window collisions in the United States is estimated at 97.6-975.6 million birds. Experimental evidence indicates that complete or partial covering of windows will eliminate bird strikes. If parts of the window are altered, objects or patterns placed on or near the window must be no more than 5-10 cm apart and uniformly cover the entire glass surface. Eliminating bird attractants from the vicinity of windows will reduce or prevent strikes by reducing the number of birds near the glass hazard. If removal of attractants is unacceptable, place them within 0.3 m of the glass surface; birds are drawn to the attractant on arrival and are not able to build up enough momentum to sustain serious injury if they hit upon departure. My experimental results further reveal that the common practice of placing single objects such as falcon silhouettes or owl decoys on or near windows does not significantly reduce bird strikes. Window casualties represent a potentially valuable, but largely neglected source of data capable of contributing information on species geographic distributions, migration patterns, and various other studies requiring specimens.
Collisions with windows remain an important human-related threat to bird survival in urban landscapes. Accurately estimating the magnitude of avian mortality at windows is difficult and may be influenced by many sources of error, such as scavenging of carcasses. Failure to account for removal of carcasses by scavengers can bias estimates of window mortality. We tested the hypothesis that carcass survival depends on local habitat factors known to influence scavenger behavior. Scavenger activity on bird carcasses was documented at 20 buildings in an urban landscape in northwestern Illinois for 1 week during each season of a year. Known-fate models were used to relate carcass survival to local habitat composition and to evaluate temporal variation in survival. We also documented species of scavengers and the timing of scavenging using motion-triggered cameras. Daily carcass survival was greater in winter than during spring, summer, and fall. Survival was related negatively to canopy cover (trees and shrubs within a 50-m buffer) and window area, and positively to pavement cover. Using an exponential model of survival time, estimated mean time of survival of carcasses (t± SE) was 82.9 ± 11.7 d for winter and 11.8 ± 7.2 d for other seasons. Raccoons (Procyon lotor) scavenged more carcasses than other species. Our results suggest that (1) carcass survival times may be short at locations with preferred habitats of known scavengers and predictable sources of food, and (2) knowledge of scavenger distribution and activity can inform predictive models of persistence. In studies of bird-window collisions, the influence of scavenger bias can be minimized by maintaining short time intervals between carcass searches. Search intervals can be inferred by estimating the number of days that a carcass should persist at a site, which can be calculated using predicted daily survival probabilities of carcasses at study buildings.
Birds migrating to and from breeding grounds in the United States and Canada are killed by the millions in collisions with lighted towers and their guy wires. Avian mortality at towers is highly variable across species, and the importance to each population depends on its size and trajectory. Building on our previous estimate of avian mortality at communication towers, we calculated mortality by species and by regions. To do this, we constructed a database of mortality by species at towers from available records and calculated the mean proportion of each species killed at towers within aggregated Bird Conservation Regions. These proportions were combined with mortality estimates that we previously calculated for those regions. We then compared our estimated bird mortality rates to the estimated populations of these species in the United States and Canada. Neotropical migrants suffer the greatest mortality; 97.4% of birds killed are passerines, mostly warblers (Parulidae, 58.4%), vireos (Vireonidae, 13.4%), thrushes (Turdidae, 7.7%), and sparrows (Emberizidae, 5.8%). Thirteen birds of conservation concern in the United States or Canada suffer annual mortality of 1–9% of their estimated total population. Of these, estimated annual mortality is >2% for Yellow Rail (Coturnicops noveboracensis), Swainson’s Warbler (Limnothlypis swainsonii), Pied-billed Grebe (Podilymbus podiceps), Bay-breasted Warbler (Setophaga castanea), Golden-winged Warbler (Vermivora chrysoptera), Worm-eating Warbler (Helmitheros vermivorum), Prairie Warbler (Setophaga discolor), and Ovenbird (Seiurus aurocapilla). Avian mortality from anthropogenic sources is almost always reported in the aggregate (“number of birds killed”), which cannot detect the species-level effects necessary to make conservation assessments. Our approach to per species estimates could be undertaken for other sources of chronic anthropogenic mortality.
Anthropogenic threats, such as collisions with man-made structures, vehicles, poisoning and predation by domestic pets, combine to kill billions of wildlife annually. Free-ranging domestic cats have been introduced globally and have contributed to multiple wildlife extinctions on islands. The magnitude of mortality they cause in mainland areas remains speculative, with large-scale estimates based on non-systematic analyses and little consideration of scientific data. Here we conduct a systematic review and quantitatively estimate mortality caused by cats in the United States. We estimate that free-ranging domestic cats kill 1.4-3.7 billion birds and 6.9-20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact.
Collisions with windows are an important human-related threat to birds in urban landscapes. However, the proximate drivers of collisions are not well understood, and no study has examined spatial variation in mortality in an urban setting. We hypothesized that the number of fatalities at buildings varies with window area and habitat features that influence avian community structure. In 2010 we documented bird-window collisions (BWCs) and characterized avian community structure at 20 buildings in an urban landscape in northwestern Illinois, USA. For each building and season, we conducted 21 daily surveys for carcasses and nine point count surveys to estimate relative abundance, richness, and diversity. Our sampling design was informed by experimentally estimated carcass persistence times and detection probabilities. We used linear and generalized linear mixed models to evaluate how habitat features influenced community structure and how mortality was affected by window area and factors that correlated with community structure. The most-supported model was consistent for all community indices and included effects of season, development, and distance to vegetated lots. BWCs were related positively to window area and negatively to development. We documented mortalities for 16/72 (22%) species (34 total carcasses) recorded at buildings, and BWCs were greater for juveniles than adults. Based on the most-supported model of BWCs, the median number of annual predicted fatalities at study buildings was 3 (range = 0-52). These results suggest that patchily distributed environmental resources and levels of window area in buildings create spatial variation in BWCs within and among urban areas. Current mortality estimates place little emphasis on spatial variation, which precludes a fundamental understanding of the issue. To focus conservation efforts, we illustrate how knowledge of the structural and environmental factors that influence bird-window collisions can be used to predict fatalities in the broader landscape.
We studied building characteristics and landscape context to predict risk of migratory birds being killed by colliding with sheet glass on Manhattan Island, New York City, New York, USA. Trained volunteers monitored 73 discrete building facades daily from the Upper East Side to the southern tip of the Island during autumn 2006 and spring 2007 bird migratory periods using a consistent and scientifically valid search protocol. We recorded 475 bird strikes in autumn 2006 and 74 in spring 2007 of which 82 and 85%, respectively, were fatal. Most building and context variables exerted moderate influence on risk of death by colliding with glass. We recommend a suite of building characteristics that building designers can use to reduce risk of collisions by minimizing the proportion of glass to other building materials in new construction. We suggest that reduction of reflective panes may offer increased protection for birds. Several context variables can reduce risk of death at glass by reducing ground cover, including changes in height of vegetation, and eliminating shrubs and trees from areas in front of buildings. We estimated 1.3 bird fatalities per ha per year; this rate extrapolates to 34 million annual glass victims in urban areas of North America north of Mexico during the fall and spring migratory periods. Clear and reflective sheet glass poses a universal hazard for birds, specifically for passage migrants in New York City, but also representative and comparable to growing urban areas worldwide.
Extensive observations and experiments suggest that collisions with plate glass result in more avian mortalities than any other human-associated factor. We tested the effects of window angling and the distance of bird feeders from windows on bird-glass collisions. Strike frequency differed among windows oriented vertically (control) and those angled 20 and 40 degrees from vertical; as the angle of orientation increased, strikes and fatalities decreased. Strike frequency and fatalities at windows also increased as the distance between bird feeders and the glass surface increased. No fatalities were recorded when feeders were located within 1 m of a window, but a marked increase in mortality occurred when feeders were placed 5 and 10 m from the glass. Most glass-collision victims may go unnoticed, hidden by vegetation where they remain out of view or are removed by scavengers. We found that scavengers frequently removed baits from beneath windows at six buildings, but no baits were taken from a site without windows that served as a control. The importance of window strikes as an avian mortality factor, and the likelihood that it will increase over time, compel us to recommend a reevaluation of the Migratory Bird Treaty Act (MBTA). Angling panes in new and remodeled buildings and placing bird feeders closer to windows can potentially reduce avian mortality.
Little is known about impacts to birds from collisions with windows at commercial buildings. We monitored bird mortality from striking windows at five commercial buildings on two college campuses in northwestern and southwestern Illinois. Bird mortality at Augustana College (northwestern), which was evaluated from 2002 to 2006, totaled 215 individuals in 48 species for an average rate of 55 birds/building/year. We calculated a mortality rate of 24 birds/building/year for 2004–2005 from 142 individuals within 37 species at Principia College (southwestern). Mortality of North American migrant (NAM) and neotropical migrant (NTM) birds was higher during migration than during summer or winter. We tested the hypothesis at Augustana that density of birds at a given location will be positively correlated with numbers of birds that die due to strikes with windows. Bird density only partially explained strikes with windows since mortality was also a function of landscaped habitat that attracted birds. Annual bird mortality at commercial buildings may be about five times higher than previous estimates. These buildings may place bird populations at high risk of strikes at windows.
Birds behave as if clear and reflective glass and plastic windows are invisible, and annual avian mortality from collisions is estimated in the billions worldwide. Outdoor flight cage and field experiments were used to evaluate different methods to prevent collisions between birds and windows. Stripe and grid patterns of clear UV-reflecting and UV-absorbing window coverings presented an effective warning that birds avoid while offering little or no obstructed view for humans. Birds used UV-reflected signals to avoid space occupied by clear and reflective sheet glass and plastic. Window coverings with effective UV-reflecting and UV-absorbing patterns as warning signals can prevent unintentional killing of birds from collisions with windows. One-way films that made the outer surface of windows opaque or translucent were successful in deterring bird strikes. Ceramic frit glass consisting of a visual pattern of densely spaced 0.32-cm diameter dots, 0.32 cm apart was an effective collision deterrent. Uniformly covering windows with decals or other objects that are separated by 5 to 10 cm was completely or near-completely effective in preventing strikes. Twice the number of window strikes occurred at non-reflective sheet glass compared to conventional clear panes. Continuous monitoring of windows revealed one in four bird strikes left no evidence of a collision after 24 hrs and, without continuous monitoring, 25% of bird strikes were undetected.
We estimate that from 500 million to possibly over 1 billion birds are killed annually in the United States due to anthropogenic sources including collisions with human-made structures such as vehicles, buildings and windows, power lines, communication towers, and wind turbines; electrocutions; oil spills and other con-taminants; pesticides; cat predation; and commercial fishing by-catch. Many of the deaths from these sour-ces would be considered unlawful take under federal laws such as the Endangered Species Act, Migratory Bird Treaty Act, and the Bald and Golden Eagle Pro-tection Act. In this paper, we summarize this literature and provide the basis for the mortality projections for many of the apparent significant sources. Most of the mortality projections are based on small sample sizes, and on studies typically lacking adjustments for scav-enging and searcher efficiency biases. Although the estimates for each source often range by an order of magnitude, the cumulative mortality from all these sources continues to be a concern.
Avian mortality at communication towers in the continental United States and Canada is an issue of pressing conservation concern. Previous estimates of this mortality have been based on limited data and have not included Canada. We compiled a database of communication towers in the continental United States and Canada and estimated avian mortality by tower with a regression relating avian mortality to tower height. This equation was derived from 38 tower studies for which mortality data were available and corrected for sampling effort, search efficiency, and scavenging where appropriate. Although most studies document mortality at guyed towers with steady-burning lights, we accounted for lower mortality at towers without guy wires or steady-burning lights by adjusting estimates based on published studies. The resulting estimate of mortality at towers is 6.8 million birds per year in the United States and Canada. Bootstrapped subsampling indicated that the regression was robust to the choice of studies included and a comparison of multiple regression models showed that incorporating sampling, scavenging, and search efficiency adjustments improved model fit. Estimating total avian mortality is only a first step in developing an assessment of the biological significance of mortality at communication towers for individual species or groups of species. Nevertheless, our estimate can be used to evaluate this source of mortality, develop subsequent per-species mortality estimates, and motivate policy action.
Avian biodiversity is threatened by numerous anthropogenic factors and migratory species are especially at risk. Migrating birds frequently collide with manmade structures and such losses are believed to represent the majority of anthropogenic mortality for North American birds. However, estimates of total collision mortality range across several orders of magnitude and effects on population dynamics remain unknown. Herein, we develop a novel method to assess relative vulnerability to anthropogenic threats, which we demonstrate using 243,103 collision records from 188 species of eastern North American landbirds. After correcting mortality estimates for variation attributable to population size and geographic overlap with potential collision structures, we found that per capita vulnerability to collision with buildings and towers varied over more than four orders of magnitude among species. Species that migrate long distances or at night were much more likely to be killed by collisions than year-round residents or diurnal migrants. However, there was no correlation between relative collision mortality and long-term population trends for these same species. Thus, although millions of North American birds are killed annually by collisions with manmade structures, this source of mortality has no discernible effect on populations.
Sociologists use the term social construction to refer to the processes by which people assign meaning to their world. This paper argues that numeracy education needs to address social construction. In particular, thinking critically about the statistics the news media report regarding social issues requires understanding the competitive nature of the social problems marketplace, and the social forces that allow questionable numbers to receive widespread public attention. Such critiques must incorporate more than assessing how the numbers were calculated; they must consider the social construction of particular statistics. Two recent examples—claims about the number of birds killed flying into windows, and warnings about the threat of an avian flu pandemic—are presented to illustrate the need to incorporate social construction into numeracy education.
Carcass searches are a common method for studying the risk of anthropogenic hazards to wildlife, including nontarget poisoning and collisions with anthropogenic structures. Typically, numbers of carcasses found must be corrected for scavenging rates and imperfect detection. Parameters for these processes (scavenging and detection) are often estimated using carcass distribution trials in which researchers place carcasses in the field at known times and locations. In this manuscript I develop a variety of estimators based on multi-event or hidden Markov models for use under different experimental conditions. I apply the estimators to two case studies of avian mortality, one from pesticide exposure and another at wind turbines. The proposed framework for mortality estimation points to a unified framework for estimation of scavenging rates and searcher efficiency in a single trial and also allows estimation based only on accidental kills, obviating the need for carcass distribution trials. Results of the case studies show wide variation in the performance of different estimators, but even wider confidence intervals around estimates of the numbers of animals killed, which are the direct result of small sample size in the carcass distribution trials employed. These results also highlight the importance of a well-formed hypothesis about the temporal nature of mortality at the focal hazard under study.
Three hundred fatalities and 31 survivors were studied to determine the types of injury, cause of death, and recuperation from collisions between birds and windows. The consequences of collisions depend on the momentum with which birds hit glass panes. The effects of window strikes for birds ranged from no visible damage to fractured bones and superficial and internal bleeding. Skeletal fractures were rare. Every fatality sustained intracranial hemorrhaging which suggests that the cause of death was ruptured blood vessels and brain damage resulting from the impact. Survivors also sustained extensive intracranial hemorrhaging, and one individual exhibited increased paralysis over time. Other survivors appear unharmed immediately after the strike or recuperate for varying periods of time before recovering completely. To increase the chance of initial recovery, place stunned or unconscious survivors in a protected enclosure isolated from excessive stimulation, keep the enclosure warm and provide food and water. ************
Abstract MOdern man,serves as both a direct and an indirect cau~e,of the death of birds. In the early 1970's, human activity was responsible for the death of approximately 196 million birds per year, or about 1.9% of the wild birds of the continental United States that died each·year.,. Hunting was the largest direct mortality factor and accounted for about 61 % of human,related bird deaths. Control or prevention of avian depredations took about 1% of tl).e total, 'and all re search and propagation about 0.5%. Collision with man~made,objects was the greatest indirect human,cause of avian deaths. accounting for about 32% of the human,related deaths. Pollution and poisoning caused the death of about 2% of the total. A relatively few speci~s,account for most of this mortality but continue to maintain large, harvestable populations, suggesting that the numbers of most bird species are essetitiaUy unaf fected by the human,activities discussed. Other activities of man,t.hat do not necessarily result in the death of birds but rather 'reduce reproductive potential are more likely to have long-term effects on avian populations.,\ The causes of avian mortality are numerous. Such
Hundreds of millions to greater than one billion North American birds are directly killed each year by human stressors, including collisions with man-made structures, predation by feral and pet cats, intentional and accidental poisoning, and pollution. Because these causes of mortality are increasingly abundant and because some result in large bird die-offs, they have received both increased scientific attention and general media coverage. However, quantifying bird mortality remains imprecise and methods to assess whether these losses cause important biological impacts remain underdeveloped. If local mortality studies followed rigorous design and sampling schemes, allowing comparison of data and scaling up of mortality estimates to broad regions, this could lead to improved analyses. Several analytical techniques - including hierarchical and population models - show potential for improving quantification of anthropogenic mortality of birds and inference of population-level effects. Results arising from improved study designs and analytical techniques will more effectively inform decision making about policies and regulations aimed at reducing avian mortality and minimizing population impacts.
For comparing impacts of bird and bat collisions with wind turbines, investigators estimate fatalities/megawatt (MW) of rated capacity/year, based on periodic carcass searches and trials used to estimate carcasses not found due to scavenger removal and searcher error. However, scavenger trials typically place ≥10 carcasses at once within small areas already supplying scavengers with carcasses deposited by wind turbines, so scavengers may be unable to process and remove all placed carcasses. To avoid scavenger swamping, which might bias fatality estimates low, we placed only 1–5 bird carcasses at a time amongst 52 wind turbines in our 249.7-ha study area, each carcass monitored by a motion-activated camera. Scavengers removed 50 of 63 carcasses, averaging 4.45 days to the first scavenging event. By 15 days, which corresponded with most of our search intervals, scavengers removed 0% and 67% of large-bodied raptors placed in winter and summer, respectively, and 15% and 71% of small birds placed in w...
Fitting a line to a bivariate dataset can be a deceptively complex problem, and there has been much debate on this issue in the literature. In this review, we describe for the practitioner the essential features of line‐fitting methods for estimating the relationship between two variables: what methods are commonly used, which method should be used when, and how to make inferences from these lines to answer common research questions.
A particularly important point for line‐fitting in allometry is that usually, two sources of error are present (which we call measurement and equation error), and these have quite different implications for choice of line‐fitting method. As a consequence, the approach in this review and the methods presented have subtle but important differences from previous reviews in the biology literature.
Linear regression, major axis and standardised major axis are alternative methods that can be appropriate when there is no measurement error. When there is measurement error, this often needs to be estimated and used to adjust the variance terms in formulae for line‐fitting. We also review line‐fitting methods for phylogenetic analyses.
Methods of inference are described for the line‐fitting techniques discussed in this paper. The types of inference considered here are testing if the slope or elevation equals a given value, constructing confidence intervals for the slope or elevation, comparing several slopes or elevations, and testing for shift along the axis amongst several groups. In some cases several methods have been proposed in the literature. These are discussed and compared. In other cases there is little or no previous guidance available in the literature.
Simulations were conducted to check whether the methods of inference proposed have the intended coverage probability or Type I error. We identified the methods of inference that perform well and recommend the techniques that should be adopted in future work.
Surveillance targeting dead wild birds, in particular American crows (Corvus brachyrhynchos), plays a critical role in West Nile virus (WNV) surveillance in the United States. Using crow decoy surrogates, detection and reporting of crow carcasses within urban and rural environments of DeKalb County, Georgia were assessed for potential biases that might occur in the county's WNV surveillance program. In each of two replicated trials, during July and September 2003, 400 decoys were labeled with reporting instructions and distributed along randomly chosen routes throughout designated urban and rural areas within DeKalb County. Information-theoretic methods were used to compare alternative models incorporating the effects of area and trial on probabilities of detection and reporting. The model with the best empirical support included the effects of area on both detection and reporting of decoys. The proportion of decoys detected in the urban area (0.605, SE=0.024) was approximately twice that of the rural area (0.293, SE=0.023), and the proportion of decoys reported in the urban area (0.273, SE=0.023) was approximately three times that of the rural area (0.103, SE=0.028). These results suggest that human density and associated factors can substantially influence dead crow detection and reporting and, thus, the perceived distribution of WNV. In a second and separate study, the persistence and fate of American crow and house sparrow (Passer domesticus) carcasses were assessed in urban and rural environments in Athens-Clarke, Madison, and Oconee counties, Georgia. Two replicated trials using 96 carcasses of each species were conducted during July and September 2004. For a portion of the carcasses, motion sensitive cameras were used to monitor scavenging species visits. Most carcasses (82%) disappeared or were decayed by the end of the 6-day study. Carcass persistence averaged 1.6 days in rural areas and 2.1 days in urban areas. We analyzed carcass persistence rates using a known-fate model framework in program MARK. Model selection based on Akaike's Information Criteria (AIC) indicated that the best model explaining carcass persistence rates included species and number of days of exposure; however, the model including area and number of days of exposure received approximately equal support. Model-averaged carcass persistence rates were higher for urban areas and for crow carcasses. Six mammalian and one avian species were documented scavenging upon carcasses. Dead wild birds could represent potential sources of oral WNV exposure to these scavenging species. Species composition of the scavenger assemblage was similar in urban and rural areas but "scavenging pressure" was greater in rural areas.
Avian mortality at windows: The second largest human source of bird mortality on earth
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A second critique of Arnold and Zink Architectural and landscape risk factors associated with bird–glass collisions in an urban environ-ment
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