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How Cities Can Better Support Birds

April 7, 2021
Article written by: Bethnewark

Birds are incredibly important. They control pests, pollinate plants, distribute seeds, and recycle nutrients. Birds provide us with eggs, meat, and feathers and the nests they build are key for the lifecycles of other organisms. Birds help us to connect with nature on a daily basis, from glancing out the window to viewing art that they inspired (Wenny, et al., 2011). However, despite all of the benefits that birds bring to human society, which we explore further in another blog post, we are not always kind to them. In fact, urban areas contain several threats to bird life, but research has shown that there are solutions.

Building Collisions

Studies estimate that between 365 and 988 million birds (a median of 599 million) are killed annually by building collisions in the U.S. (Loss, Will, Loss, & Marra, 2014). A combination of factors cause this: reflections from windows that confuse birds, light pollution that disorientates them, and tall buildings being located directly in flight paths and habitats of many species (Berg, 2021).

Bird-friendly glass is one way to reduce building collisions; this can include dotted patterns, tints, or glazing on glass and windows. Birds can mistake reflective surfaces like windows and glass for sky or vegetation and fly straight into the buildings as a result, the textures glass prevents this from happening. To increase the use of bird friendly materials in building works, legislation must be passed that requires its use in new constructions and major renovations. An example of this kind of legislation is a bill entitled “A Local Law to amend the administrative code of the city of New York and the New York city building code, in relation to bird friendly materials” introduced in March 2020 in New York City. This bill requires that at least 90% of the exterior of the first 75 feet of a building is constructed with bird-friendly materials. Proof of the effectiveness of similar policies are exemplified by cases such as the Jacob K. Javits Convention Center in Manhattan, which replaced its windows with fritted glass in 2013. The result, according to NYC Audubon, was a 90% reduction in bird deaths (Liao, 2019).

Measures to reduce the impact of light pollution on migrating birds are also key. Billions of birds migrate each year, typically flying at night and navigating using the night sky (Audubon, 2020). Turning off outdoor lighting between 11 p.m. and dawn during peak migration periods can help to provide birds with safe passage between their nesting and wintering grounds (Liao, 2019) (Audubon, 2020).  


It’s not just architects who play a role in making urban environments better for birds, it’s pet owners too. Building collisions are the second largest source of human-caused mortality for U.S. birds. The only greater threat comes from feral and free-ranging cats, which are estimated to kill roughly four times as many birds each year as building collisions (Loss, Will, Loss, & Marra, 2014). Free-ranging domestic cats have been introduced to habitats all of the world. Research suggests that feral cats on islands contribute to at least 14% of global bird, mammal, and reptile extinctions and are the primary threat to up to 8% of critically endangered birds, mammals, and reptiles (Medina, et al., 2011). Estimates say that free-ranging domestic cats kill between 1.3–4.0 billion birds and 6.3–22.3 billion mammals each year, and that un-owned cats, rather than pet cats, cause the majority of the mortality (Loss, Will, & Marra, 2013).

Scientifically sound intervention in both wildlife conservation and policy is essential to reduce this impact (Loss, Will, & Marra, 2013). One strategy that cat owners can employ to prevent their pets from harming wildlife is to build “catios”. “Catios” or cat-patios are screened-in structures that allow pet cats to have the experience and stimulation of being outside. They are always closed in which means cats do not have the opportunity to hunt or kill birds (Berg, 2021). Other mitigation measures that have been proposed to protect wildlife from cat predation include devices designed to hinder cat hunting ability, such as those that make a noise to alert birds to their presence. It is also thought that desexing cats will reduce their impulse to wander and exhibit nuisance behaviours. Keeping cats indoors at night, or at all times, would also remove their ability to hunt wildlife. There are suggestions that regulations could be brought in that govern and restrict cat ownership. These regulations could include limits on the number of pet cats per household to reduce cat density, or could prohibit cat ownership in zones around sensitive wildlife conservation areas (Metsers, Seddon, & van Heezik, 2010).

Cultural Importance

Birds provide cultural benefits to humans as sources of recreation including birdwatching and hunting, as pets, as symbols in religious customs, and by serving as inspiration for photography and art (Michel, Whelan, & Verutes, 2020). Cities are often where people come into contact with the natural world: in urban nature reserves, residential yards, and parks. One of the most important aspects of birds in urban areas is acting as the link between urban spaces and the natural environment (Belaire, Westphal, Whelan, & Minor, 2015).

Studies have found that people who engage in wildlife recreation are 4-5 time more likely to engage in conservation behaviours. These behaviours include donating to local conservation efforts, enhancing wildlife habitats on public land, advocating for wildlife recreation, and taking part in local environmental groups (Cooper, Larson, Dayer, Stedman, & Decker, 2015). Since people who partake in wildlife recreation and birdwatching are more likely to exhibit environmental behaviours, the key may lie in encouraging more people to participate. Improving accessibility to green spaces could be one way to attract more birdwatchers (Zhang & Huang, 2020). Birdwatching is also one of the most sustainable types of wildlife tourism and contributes to economic development and environmental management of rural and remote areas (Connell, 2009). Therefore, increase participation may hold benefits to humans and birds alike.


Cities are where people commonly come into contact with birds, but they contain many hazards. These hazards include collisions with buildings, predation from cats, and exclusion by the lack of green spaces. Bird conservation is important not just for the sake of biodiversity but for the sake of human life;  including birds in city planning, pet policies, and green spaces in cities is essential.


Audubon. (2020). Creating Bird-Friendly Communities: Lights Out. Retrieved from Audubon:

Belaire, J. A., Westphal, L. M., Whelan, C. J., & Minor, E. S. (2015). Urban residents' perceptions of birds in the neighborhood: Biodiversity, cultural ecosystem services, and disservices. The Condor, 117(2), 192-202.

Berg, N. (2021, February 8). Why cities should be designed for birds. Retrieved from Fast Company:

Liao, K. (2019, December 10). New York City Passes a Landmark Bill to Make More Buildings Bird-Friendly. Retrieved from Audubon:

Loss, S. R., Will, T., & Marra, P. P. (2013). The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications.

Loss, S. R., Will, T., Loss, S. S., & Marra, P. P. (2014, January 2). Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability. The Condor, 116, 8–23.

Medina, F. M., Bonnaud, E., Vidal, E., Tershy, B. R., Zavaleta, E. S., Dolan, C. J., . . . Nogales , M. (2011, June 3). A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology, 17(11), 3503-3510.

Metsers, E. M., Seddon, P. J., & van Heezik, Y. M. (2010). Cat-exclusion zones in rural and urban-fringe landscapes: how large would they have to be? Wildlife Research, 47-56.

Michel, N. L., Whelan, C. J., & Verutes, G. M. (2020). Ecosystem services provided by Neotropical birds. The Condor, 122(3), 1-21.

Wenny, D. G., Devault, T. L., Johnson, M. D., Kelly, D., Sekercioglu, C. H., Tomback, D. F., & Whelan, C. J. (2011). The Need to Quantify Ecosystem Services Provided By Birds. The Auk, 128(1), 1-14.