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We used direct observation to record what, if any, evidence was measurable when a bird hit the outside surface of plate glass during 18 field experiments to evaluate several products to deter window strikes. A total of 1,356 strikes were witnessed over 508 d and 1,202 h of observation; 678 (50%) left no evidence of a collision, and 190 (14%) resulted in an immediate fatality. For 10 experiments, 1,261 detailed individual flightpaths were drawn over 235 d and 799 h of observation; 916 (73%) were strikes and 22 (2%) of these resulted in an immediate fatality. We recorded 822 (90%) flightpaths that hit perpendicular or within 40[degrees] on either side of perpendicular to the glass surface; 94 (10%) hit with a glancing blow of greater than 40[degrees] on either side of perpendicular. Perpendicular strikes resulted in 689 (84%) of individuals flying off immediately with no sign of impairment, 113 (14%) stunned, and 20 (2%) fatalities. Glancing blow strikes resulted in 81 (86%) flying off with no sign of impairment, 11 (12%) stunned, and 2 (2%) fatalities. Considering that 50% of bird--window collisions leave no measurable evidence of a strike, and as much as 70% of stunned victims likely succumb from a collision, annual mortality may be minimally 1.28 billion--3.46 billion or as high as 1.92 billion--5.19 billion in the United States, with potentially billions more worldwide. Received 3 July 2023. Accepted 29 December 2023. Key words: field experiment, glass, strike injury and remnants. Usamos observaciones directas para reportar que evidencia, de existir, era inedible cuando un ave golpeaba la superficie externa de un vidrio durante 18 experimentos de campo para evaluar varios productos para evitar colisiones contra ventanas. Un total de 1,356 colisiones fueron observadas durante 508 dias y 1202 horas de observacion; 678 (50%) no dejo evidencia de colision y 190 (14%) resulto en una fatalidad inmediata. Para 10 experimentos, 1,261 rutas de vuelo individuales detalladas se dibujaron durante 235 dias y 700 horas de observacion; 916 (73%) fueron colisiones y 22 (2%) resultaron en una fatalidad inmediata. Registramos 822 (90%) rutas de vuelo que impactaron perpendicularmente o dentro de los 40[degrees] en alguno de los lados a la perpendicular a la superficie del vidrio; 94 (10%) golpearon con un golpe oblicuo mayor a 40[degrees] en algun lado de la perpendicular. Impactos perpendiculares resultaron en 689 (84%) de individuos que volaron inmediatamente sin signos de dano, 113 (14%) aturdidos y 20 (2%) fatalidades. Considerando que el 50% de las colisiones ave-ventana no dejan evidencia medible de un golpe y que hasta un 70% de las victimas impactadas posiblemente sucumben a la colision, la mortalidad anual puede ser un minimo de 1.28 mil millones a 3.46 mil millones o un maximo de 1.92 mil millones a 5.19 mil millones en Estados Unidos, potencialemtente miles de millones en el mundo. Palabras clave: experimento de campo, vidrio, herida por colision y remanentes., We investigated the fates of birds striking windows by documenting the details of individual collision events. Documenting the categorical level of severity from a large sample of individual collision events [...]

Billions of birds are estimated to be killed striking clear and reflective windows worldwide, and conservation, ethical, and legal reasons justify preventing this unintended human-associated avian mortality. Field experiments reveal that to be effective, UV signals used to prevent bird-window collisions must minimally reflect 20-40% from 300-400 rim. Field experiments reveal 3.175 mm parachute cord hung in front of clear and reflective windows separated by 10.8 cm and 8.9 cm are effective bird-window collision preventive methods. The results of the parachute cord experiment and those of previous studies support the importance of applying collision prevention methods to the outside window surface reflecting the facing habitat and sky. Comparison of field and tunnel testing experimental protocols to evaluate bird-window collision preventive methods suggest that tunnel testing is useful for initial assessment but not as a definitive measure of effectiveness. Received 6 January 2012. Accepted 19 December 2012. Key words: collision prevention, testing, ultraviolet (UV) signals, visual information, windows., Except for habitat destruction, the casualties attributable to bird-window collisions total in the billions worldwide and are estimated to be greater than any other human-associated source of avian mortality (Klein [...]

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., Avian mortality resulting from collisions with clear and reflective sheet glass and plastic is estimated to be in the billions worldwide (Klem 1990, 2006). Collisions are predicted and expected wherever [...]

Collisions with buildings cause up to 1 billion bird fatalities annually in the United States and Canada. However, efforts to reduce collisions would benefit from studies conducted at large spatial scales across multiple study sites with standardized methods and consideration of species- and life-history-related variation and correlates of collisions. We addressed these research needs through coordinated collection of data on bird collisions with buildings at sites in the United States (35), Canada (3), and Mexico (2). We collected all carcasses and identified species. After removing records for unidentified carcasses, species lacking distribution-wide population estimates, and species with distributions overlapping fewer than 10 sites, we retained 269 carcasses of 64 species for analysis. We estimated collision vulnerability for 40 bird species with ≥2 fatalities based on their North American population abundance, distribution overlap in study sites, and sampling effort. Of 10 species we identified as most vulnerable to collisions, some have been identified previously (e.g., Black-throated Blue Warbler [Setophaga caerulescens]), whereas others emerged for the first time (e.g., White-breasted Nuthatch [Sitta carolinensis]), possibly because we used a more standardized sampling approach than past studies. Building size and glass area were positively associated with number of collisions for 5 of 8 species with enough observations to analyze independently. Vegetation around buildings influenced collisions for only 1 of those 8 species (Swainson's Thrush [Catharus ustulatus]). Life history predicted collisions; numbers of collisions were greatest for migratory, insectivorous, and woodland-inhabiting species. Our results provide new insight into the species most vulnerable to building collisions, making them potentially in greatest need of conservation attention to reduce collisions and into species- and life-history-related variation and correlates of building collisions, information that can help refine collision management., (© 2020 Society for Conservation Biology.)

Sheet glass and plastic in the form of clear and reflective windows are universally lethal to birds. Reasonable interpretation of available scientific evidence describes windows as a principal human-associated avian mortality factor that is an indiscriminant killer of common species as well as species of conservation concern. A conservative toll estimates 1 billion or more annual fatalities in the United States alone. The injury and death from birds striking windows are foreseeable and preventable, but the most promising legal measures and commercial products are not being applied or made available to protect defenseless victims. Avian window casualties are important for birds and people, and they have nonhuman animal welfare, biodiversity, sustainability, legal, and ethical and moral value justifying responsible human action. Preventing this unintended and unwanted lethal hazard for free-flying birds should be an obligation. Short-term solutions include retrofitting existing panes with a variety of proven measures that among others include applying various materials to cover the outside surface of windows. Long-term solutions include current and proposed bird-safe sheet glass and plastic for remodeling and new construction that have patterns that transform windows into barriers that birds see and avoid.