Year-round monitoring reveals that environmental factors largely explain variation in bird-window collisions on a university campus in Brazil

Bird-window collisions cause an estimated one billion bird deaths annually in the United States. Building characteristics and surrounding habitat affect collision frequency. Given the importance of collisions as an anthropogenic threat to birds, mitigation is essential. Patterned glass and UV-reflective films have been proven to prevent collisions. At Duke University’s West campus in Durham, North Carolina, we set out to identify the buildings and building characteristics associated with the highest frequencies of collisions in order to propose a mitigation strategy. We surveyed six buildings, stratified by size, and measured architectural characteristics and surrounding area variables. During 21 consecutive days in spring and fall 2014, and spring 2015, we conducted carcass surveys to document collisions. In addition, we also collected ad hoc collision data year-round and recorded the data using the app iNaturalist. Consistent with previous studies, we found a positive relationship between glass area and collisions. Fitzpatrick, the building with the most window area, caused the most collisions. Schwartz and the Perk, the two small buildings with small window areas, had the lowest collision frequencies. Penn, the only building with bird deterrent pattern, caused just two collisions, despite being almost completely made out of glass. Unlike many research projects, our data collection led to mitigation action. A resolution supported by the student government, including news stories in the local media, resulted in the application of a bird deterrent film to the building with the most collisions: Fitzpatrick. We present our collision data and mitigation result to inspire other researchers and organizations to prevent bird-window collisions.

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.

Window strikes are among the most worrisome causes of bird mortality. Being responsible for billions of avian deaths, bird-window collisions have been widely studied in the US and Canada, with few studies from Europe, Asia, and Latin America. Thus, there is still a dearth of knowledge regarding this alarming phenomenon in regions where biodiversity and urbanization peek, such as Latin America. In this study, we assessed bird-window collisions in Xalapa, a small-to-medium-sized Neotropical city located in Southeast Mexico. We gathered data under two schemes: (1) a standardized survey procedure and (2) non-systematic records. Regarding the former, we evaluated the role of building and surrounding vegetation traits, as well as the location of focal buildings in driving bird-window collisions. Considering both schemes, we recorded bird-window collisions for 43 species. The most frequent striking groups were hummingbirds and thrushes, which had already been identified as vulnerable given some of their natural and life history traits. Regarding the standardized survey, we found no statistical differences in the number of collisions among seasons; yet, we did record a predominance of strikes from resident bird species over migrants among all studied seasons. Our results show a significant positive relationship between the amount of surrounding vegetation area of the studied buildings and bird-window collision frequency, while building non-glass material area showed a significant negative relationship. Based on our findings and the limitations of our study, we encourage future research to combine systematic and standard surveys throughout the year with citizen science, together with carcass removal assessments and bird density surveys in the immediate vicinity of focal buildings.

Bird-window collisions are a dramatic cause of bird mortality globally. In Latin America, statistics are generally very scarce and/or inaccessible so the frequency of such incidents is still poorly understood. Nevertheless, civilians have applied preventive methods (e.g. adhesive bird-of-prey decals) sparsely but, to our knowledge, no study has evaluated their effectiveness in Brazil. Here, we estimated the mortality rate of bird-window collisions and tested the effectiveness of bird-of-prey decals at preventing such accidents. We undertook daily searches for bird carcasses, presumably resulting from window collisions, near all buildings on a university campus over seven months. Adhesive bird-of-prey decals were then applied to the two buildings with the highest mortality rates and surveys continued for over 12 more months. The mortality rates before and after the application of decals and between seasons were then compared using Friedman test. We recorded 36 collisions, 29 around the two buildings with the highest collision rates 19 prior and 10 after our intervention with associated collision rates of 0.08 and 0.04 collisions/day. Although mortality was reduced by almost half, this difference was not statistically significant. The Blue-black grassquit, Volatinia jacarina (Linnaeus, 1766), and Ruddy ground dove, Columbina talpacoti (Temminck, 1810) suffered the highest number of collisions, followed by the Rufous-collared sparrow, Zonotrichia capensis (P. L. Statius Muller, 1776). Our bird-of-prey decals and efforts were insufficient to prevent or dramatically reduce the number of bird-window collisions. Therefore, we recommend that different interventions be used and additional long-term studies undertaken on their efficacy.

BackgroundTo reduce bird fatalities from millions of window collisions each year in North America, it is important to understand how design and landscape elements relate to collision risk. The current study extends prior research that found that buildings near ornamental pear trees (Prunus calleryana) and buildings with mirrored windows significantly increased odds of collisions among eight buildings on the University of Utah campus in winter. The previous study found bird-friendly glass was not related to collision risk, although only one fatality occurred at two buildings with ORNILUX® ultraviolet (UV) or fritted windows. We reasoned that extending data collection to include fall might provide a better test of efficacy. We tested the following three hypotheses: (1) Buildings with mirrored windows would experience more collisions, replicating the original study; (2) the addition of fall migration data would reveal fewer collisions at the buildings with bird-friendly windows; (3) the danger of pear tree proximity would be heightened in winter, when fruit is ripe enough to appeal to frugivores, especially the Cedar Waxwings (Bombycilla cedrorum) that frequent these trees.MethodsTrained observers monitored buildings three times per week in Fall (September 12 to October 27, 2019) and Winter (October 29, 2019 to January 24, 2020). Collisions were photographed and documented in the iNaturalist University of Utah Bird Window Collision Project.ResultsThere were 39 total collisions, from 0 to 14 per building.Using generalized estimating equations, buildings near pear trees had 3.33-fold increased odds, mirrored windows had 5.92-fold increased odds, and bird-friendly windows had an 84% lower odds (Odds ratio = 0.16) of bird window collisions when analyzed separately; all were statistically significant (p < 0.01). A test of all possible combinations of risk and protective factors revealed that the best fit model included pear trees (odds = 2.31) and mirrored windows (odds = 2.33). A separate analysis tested the pear tree by season interaction model; it yielded the deadliest combination, with 40-fold increased odds for buildings near pear trees in winter season.DiscussionThis research provides the first peer-reviewed evidence found for the efficacy of bird-friendly fritted windows and ORNILUX ® UV windows in buildings. In addition, it replicated a study that established the dangers of mirrored windows and fruiting pear trees near buildings. These risks were especially dangerous to Cedar Waxwings, who constituted 62.2% of the identifiable window collision victims. This research highlights how building risks depend on window design, landscape choices, species, and season. If replicated, analyses of risk factors can help identify buildings that require mitigation to make existing windows less deadly. Results also support the installation of bird-friendly glass in new or renovated buildings to reduce fatalities.

Bird-window collisions are a major cause of bird mortality in the world; up to one billion birds die each year from collisions with glass panes in North America alone. However, relatively little attention had been given to this issue in the broad scientific literature, despite a recent increase in the number of papers. In this paper, the indexed literature on bird-window collisions was reviewed, specifically addressing the causal factors. The search retrieved 53 papers, mostly from North America. The factors linked to higher collision rates were large areas of continuous glass, the presence of nearby vegetation and feeders, bird migration, abundance, and behavior. Several factors were site-specific, preventing the global extrapolation of these findings. There is a lack of scientific knowledge regarding bird-window collisions in tropical countries. One of the challenges to mitigating this problem is the small amount of information and - frequently - the extrapolation of findings described for temperate regions to other areas. There is a need for a greater and urgent effort to fill this gap.

With the development of urbanization, bird collisions with buildings have become increasingly frequent, resulting in significant bird deaths worldwide each year. In North America, hundreds of millions of birds die annually from collisions with buildings. The risks posed by building collisions have already jeopardized bird species diversity. Bird collisions are particularly common during migratory periods. Fatalities from bird-window collisions have a significant impact on ecosystems. Researchers in North America have conducted extensive research and experimentally validated bird collision prevention measures in various regions, which can effectively reduce avian mortality rates from collisions with buildings. While precise national statistics are lacking in China, existing research indicates that a significant number of birds also die from collisions with buildings. However, relevant research is limited in China and there is a lack of effective mitigation strategies. Therefore, this paper aims to develop bird collisions prevention measures applicable to Chinese avian populations, drawing on existing research on bird collisions in North America and incorporating it into existing research in China.

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.

Green buildings (i.e., LEED certified buildings) emphasize access to daylight and views for occupants’ wellbeing, comfort, and productivity. Window glazing allows access to daylight and views but is often detrimental to birds. Annually, up to a billion bird in the United States die due to window collisions. A comprehensive literature review and data analysis of LEED and methods of deterring collisions was conducted to determine solutions to limit bird deaths at LEED certified buildings. Deterrence factors of building design, outdoor surroundings, and occupant behavior were evaluated, due to their collective impact on bird-window collisions. To best prevent collisions and adhere to LEED, window glazing with visual markers and sound deterrents should be used. Certain façades should be avoided and building lights should be turned off during migration season. Additionally, vegetation near buildings is encouraged in LEED certification, but increases the frequency of bird-window collisions. These findings suggest that LEED, particularly the credit “Daylight and Quality Views,” is not completely aligned with current bird-safe design practices. While certain window glazing is acceptable for both LEED and bird-safe design, the two are not mutually exclusive. Due to this, it is recommended that window glazing that aligns with LEED and is bird-safe, is made clear within the LEED “Daylighting and Quality Views” credit description. LEED and bird-safe design practices also have contradictory views on vegetation near buildings. There should also be further research into if vegetation near buildings would still increase bird-window collisions if deterrent factors, such as bird-safe windows, were utilized.

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 &amp;gt; rural residences without feeders &amp;gt; urban residences with feeders &amp;gt; urban residences without feeders &amp;gt; 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.

Continent-wide analysis of how urbanization affects bird-window collision mortality in North America

Bird-window collisions are a significant and growing threat to birds, but the issue is still understudied in many geographical areas and stages of the avian annual life cycle. The mountainous topography and numerous distinct biogeoclimatic zones along the Pacific coast of Canada and the United States may result in regional and seasonal differences in collision mortality and species vulnerability to collisions. We surveyed daily for evidence of bird-window collisions over six 21-day periods in fall, early winter, and late winter between 2019 and 2022 at a university campus in southwestern British Columbia, Canada, and assessed individual species’ vulnerability to collisions by examining whether species-specific collision rates were disproportionate to their local abundance. We accounted for poor detectability of some species in fall, by integrating point count data from our study site with mist net capture data from a nearby banding station to improve abundance estimates. Collision mortality peaked in fall, but early winter collision mortality was significantly higher than in the later winter months, potentially due to movements of altitudinal migrants into our low-elevation study area in early winter. We estimated that an average of 885–1,342 (median = 1,095) birds are killed at 51 buildings campus-wide each year between September 15 and February 10, the peak fall migration wintering period. Forest birds, particularly species that switch to highly frugivorous diets in fall and winter, were most vulnerable to collisions across the seasons studied. Non-breeding season mortality due to collisions may be substantial for these species, particularly when considering cumulative mortality across the entire non-breeding period. The potential role of collision mortality in species declines should be further explored by assessing collision frequency and species vulnerability across life cycle stages in other geographical locations, and through improved data on migratory connectivity and linkages between declining breeding populations and non-breeding season mortality.

Cities and towns in developing countries increasingly face the challenge of balancing urban conservation and development due to rapid urbanisation and development pressure. Modernism, that resulted in spatially fragmented towns and cities worldwide, together with urban development and urban conservation in South Africa regulated by separate legislation, place built environment heritage resources at risk of destruction because they are being treated as isolated objects, instead of an intrinsic part of the contemporary urban fabric. This paper is based on a research project conducted for the City of Matlosana in the North-West Province, South Africa that aimed to develop proposals to integrate urban conservation and urban development in Klerksdorp, the second oldest city in the old Transvaal Republic (today divided into the North West, Gauteng, Mpumalanga and Limpopo Provinces). The process followed a qualitative participatory approach. Data was collected from archival records, a field survey and interviews with participants and other stakeholders. The findings revealed spatial fragmentation of built heritage distribution and non-alignment of planning and management processes with regard to urban conservation and development decision-making. A three-tier framework for integrating built heritage in urban development is proposed that consists of: (i) physical/spatial integration through physical planning and design, (ii) integration of urban conservation and urban development through local policy/legislation and (iii) procedural integration in terms of decision-making. A paradigm shift in urban conservation is suggested from preserving heritage resources as isolated objects towards a more proactive integration into the contemporary uses and future development of cities.

I read with interest both Strahl's (1992) and Foster's (1993) commentaries on furthering avian conservation in Latin American countries. They are correct that Latin American workers urgently need more support in conservation and research efforts in their countries and that North Americans should become involved in appropriate ways. Most of the emphasis in the two commentaries was on the role of individuals. Strahl, however, also mentioned several activities that might be undertaken by the American Ornithologists' Union as an institution. Several of these suggested activities are already underway, and the fact that Strahl was unaware of them suggests that the AOU's efforts should be much better publicized. It is important to remember that the AOU is not a conservation organization per se. Its charter (under which it is incorporated and obtains its tax-exempt status) states that the AOU's purposes are (1) the advancement of ornithology through publications, support of scientific research and the organization of conferences and meetings, and (2) the conservation of birds by providing a scientific basis for management activities and education. Within these limits the AOU has become involved in the support of Latin American ornithologists and more can be done. Strahl cited the directory to ornithology in the Neotropics that was published by the AOU's Conservation Committee (Copperband 1985). This directory provided information about Latin American individuals, organizations, and institutions that are involved in ornithological research and conservation. It was published in English, Spanish, and Portuguese. The directory (English version) has now been updated by the AOU's more recently formed Committee on PanAmerican Affairs (see Rosenberg and Wiedenfeld, 1993). The AOU's Grants, Awards and Prizes in Ornithology (Banks 1989) was distributed gratis to all Latin American members of the AOU and to more than 100 Latin American libraries (listed by Davis 1989). The third edition of the grants booklet (Grubb 1993) includes a table showing eligibility requirements and restrictions on the locality and nature of the research being supported. A few of the grants are restricted to Latin American workers and/or conservation in the Neotropics. Many have no restrictions. Of the AOU's research awards, none is exclusively for Latin American workers, but the Alexander Wetmore Research Awards are aimed primarily at systematic, paleontological, or Neotropical research projects. To date most of the Wetmore Awards relating to the Neotropics have been made to North American students, but they are equally available to Latin American applicants. Both the AOU's Wetmore and Van Tyne Funds are legally restricted (by the donors) to the support of research and cannot be used for activities that are solely conservationist in nature. In 1992 the AOU, through its Committee on PanAmerican Affairs, provided funds for four students (from Mexico, Brazil, and Argentina) to attend the meeting in Ames, Iowa. Funding for this activity was not provided for the Alaska meeting in 1993, but grants totalling $5,000 will help Latin American students attend the 1994 meeting in Missoula, Montana. That joint meeting of the AOU, Cooper Ornithological Society, and the Wilson Ornithological Society should be very well attended and should provide an excellent opportunity for interaction of Latin American and North American workers. In 1991 the AOU reduced dues for all Latin American members (and those from certain other countries) to the equivalent of the student rate. A system exists that permits AOU members to sponsor Latin American (and other) members or libraries. This opportunity was publicized in the Ornithological Newsletter (No. 78, 1990) and a Recent Ornithological Literature supplement (108:4, 1991), but the response has been limited. (However, one member generously provided five-year subscriptions to a library in each of four countries where he had done fieldwork.) Sponsorship of an individual or library is a significant, relatively inexpensive, and easy way for individuals to help Latin Americans. The AOU assisted the IVth Neotropical Ornithological Congress (Quito, Ecuador, 1991) through direct support ($2,500) and travel grants ($2,700). Additionally, the AOU applied for and received an NSF grant for $10,000 for a symposium on collection management at the congress, organized jointly by individuals from Mexico and Colombia. That grant provided travel assistance for symposium participants and made it possible to publish (in Spanish) and distribute the symposium contributions throughout Latin America (see Escalante-Pliego 1993). In 1987 the AOU obtained a grant from the Pew Charitable Trusts to survey Latin American naturalhistory libraries and to publish the results (Davis 1989). The publication includes information about the size of each library and its emphasis, the number of sci-

Collisions with human-made structures such as the windows of buildings and houses are a significant source of bird mortality worldwide and a leading cause of avian fatalities. However, research across many countries and continents, including Europe, remains limited, particularly in northern regions like Finland. This study provides an exploratory assessment of bird-window collisions in southern Finland, focusing on the cities of Lahti and Helsinki. We conducted surveys across 180 buildings, documenting 29 collisions (both lethal and non-lethal) involving 14 species (in addition to three unidentified corvids and one unidentified larid), with the goldcrest &lt;i&gt;Regulus regulus&lt;/i&gt; being the most frequent victim, both in lethal and non-lethal collisions. Our carcass removal experiment revealed that all carcasses were removed during the day, most within the first 6 hours and the remainder within 13 hours and 45 minutes, mainly by scavengers such as hooded crows &lt;i&gt;Corvus cornix&lt;/i&gt;. Notably, no nocturnal removal activity was recorded. These findings highlight the importance of carcass persistence studies in accurately estimating collision mortality. Despite potentially high collision rates, standardized data in Finland remains scarce, underscoring the need for comprehensive research to evaluate the real magnitude of bird-window collisions and their conservation impact. Thus, we recommend prioritizing bird-window collision monitoring, including multi-city surveys in different types of habitats surrounding the studied buildings and include carcass removal assessments. Furthermore, evidence-based mitigation strategies derived from local or regional data are urgently needed to address this historically overlooked, though recently recognized, conservation challenge.