Why are Glass Buildings Bird Killers? (and how to stop it from happening)

If you live in a city, especially a large,
densely populated one – chances are you’ve seen many buildings exteriors made either
mostly, or completely out of glass. It’s a building style that appeals to some
who enjoy the modern, sleek aesthetic. Glazed perimeters also provide a lot of access
to natural light, which can be a good for health and sustainability. However – there’s a hard truth about this
type of architecture that’s not often talked about. It is estimated that – here in North America,
between 700 million to 1 billion birds are killed every single year flying into glass
facades. I personally love birds and am devastated
by statistics like this, but even if you’re indifferent or don’t like birds, it’s
important to recognize that the destruction of wildlife habitat has devastating impacts
to our ecosystem that are ultimately harmful to humans. So, what are the root causes of this problem
and what can we do to prevent it from happening? Many migratory birds have evolved to fly at
night when the temperature is cooler and when they’re safer from predators. During flight, birds will use natural cues
to navigate, such as light emanating from the moon and stars. Excessive light spilling from urban areas
obscure these natural cues. Additionally many birds are attracted to bright
urban lights. This disorients and confuses them which often
results in birds getting trapped in unfamiliar urban environments. Light pollution is also a problem for more
than just birds. It disrupts the natural habitat of many animals,
contribute to energy waste and economical inefficiencies, and can result in negative
health consequences in humans, such as disruptions to our natural circadian rhythm. Thus, mitigating light pollution will not
only decrease bird fatalities, but also improve the safety and wellbeing of all animals,
including humans. So why do birds fly into glass? Well, transparent glass is actually highly
reflective when viewed from the outside. Since birds cannot distinguish the difference
between reflections and real objects, they’re highly likely to mistaken reflections of the
sky, trees and surrounding habitat as reality, and will attempt to fly into them. Clear transparent glass where the other side
can be seen is also dangerous. As birds will attempt to fly through what
they perceive to be an opening. This happens a lot at glass skywalks, glass
atriums, outdoor glass railings, glass balconies and perpendicular glass corners, The force
of impact when birds strike the glass often result in death. The biggest problem is not even high-rise
buildings. While migratory birds usually fly at altitudes
over 500 ft, or 150m, they tend to descend to much lower altitudes during inclement weather. Additionally – reflections of trees and surrounding
natural habitat are worse than reflections of the sky – as they’re attractive elements
for birds. Thus, low-rise buildings, and residential
homes actually account for significantly higher rates of bird fatalities than mid and high-rise
buildings. Glass collisions also kill birds indiscriminately
regardless of species, size, age, or physical health. Natural hazards tend to kill weaker individuals,
however glass collisions can kill some of the strongest and healthiest birds that would
have gone on to produce offspring in the natural environment. So you might be wondering. Why does this matter? How do bird fatalities affect us? Those are great questions, Betty! And they’re important questions that come
up often when we start looking into human-wildlife conflicts like bird window strikes. Birds are a group of vertebrate animals. Over the course of their evolution, birds
have diversified to include everything from ostriches to hummingbirds. And as birds evolved and diversified, they
became important members of their home ecosystems. For instance, hummingbirds are important pollinators
of certain flowers – without hummingbirds, these plants wouldn’t be able to make seeds. And without birds like cardinals, cedar waxwings,
and other songbirds that eat fruits, those seeds wouldn’t be distributed across the
landscape and able to grow plants of their own. And these are just two jobs that birds can
do! Many of the birds I just mentioned are migratory,
meaning that they spend part of the year in one geographic location, then travel enormous
distances to spend another part of the year somewhere else. Birds migrating across North America are normally
moving north-to-south and vice versa. They spend the winters in the south where
it’s warm and they can find food, then travel north in the spring and summer in order to
breed and raise their families. There are four major flyways across North
America, and basically any major metropolitan area you can think of will be in the path
of one of these: the Atlantic Flyway, the Mississippi Flyway, the Central Flyway, and
the Pacific Flyway. So basically anywhere you go, there will be
birds in danger of running into windows. I live in Toronto, Ontario where it’s estimated
at least 1 million birds die every single year due to fatal window collisions. This is a disproportionately high compared
to other North American cities due to Toronto’s position adjacent to Lake Ontario,
which is at the confluence of multiple bird migratory flyways, paired with the fact that
it’s the fourth most populous city in North America, with hundreds of thousands of low,
mid and high-rise buildings potentially hazardous to flying birds. The good news is that, there are a lot of
relatively simple and cost effective solutions to prevent bird fatalities. Lighting is an integral part of life as it’s
required for safety, security, and navigation in the urban environments at night. Good lighting design should effectively provide
for these functions in energy efficient ways while minimizing negative impacts to humans
and animal life. Some of the worst culprits of light pollution
are lights that point up, or emitting light in all directions, resulting in massive energy
loss, as much of the light emitted isn’t pointed at where it’s needed. Many urban areas are also over lit – for example
most parking lots, side walks and loading docks only require an illumination level of
10 lux at ground or tread level, yet many of these spaces are lit tens or hundreds of
times higher than that. Again, this is not only bad for birds, it
negatively impacts human circadian rhythms, provide poor illumination, result in excessive
glare which is bad for safety and navigation, renders stargazing impossible in urban areas,
and is highly energy inefficient. This is why it’s important to reduce lighting
to a properly lit level. Exterior lighting fixtures should include
cut-off shields and lamps with directional control to reduce lighting loss. Building features should be highlighted with
downlighting as opposed to uplighting. Searchlights should not be used during bird
migration periods. And automatic control systems like timers,
occupant and motion detectors can be used to automatically turn off lights both inside
and outside buildings when not needed. On an individual basis – just by drawing your
shades after dark, you can help in reducing light pollution. When it comes to glass, the vast majority
of bird collisions are actually caused by untreated reflective and/or transparent glass. One easy strategy is to only use glass with
a reflectance value of less than 15 percent on all exterior surfaces. This will reduce bird collisions to an extent,
but won’t be able to solve the “see-through-effect,” so this strategy should be combined with other
glass treatment solutions, such as applying visual markers through ceramic frit, acid-etching,
or applied film patterns. This approach still allows the glass to be
transparent or translucent, but gives the appearance of a solid surface to birds. Studies have shown that birds will not attempt
to fly through horizontal spaces less than 5cm (2”) nor vertical spaces less than 10cm
(4”), and patterns covering as little as 5% of the total glass surface can prevent
90% of bird strikes. In addition, visual markers can be used to
achieve other design objectives such as privacy screening, reducing light and heat transmission,
and integrating branding. Other glass treatment strategies include using
opaque or translucent glass – such as frosted glass, stained glass, or glass blocks. UV glass – which absorb and reflect UV light
are also effective as birds have evolved to perceive UV wavelengths that humans can’t. Recessed windows designs, balconies, awnings,
screens, shutters and sunshades can also reduce the amount of glass visible to birds, as well
as acting as solid visual cues for birds to avoid. These elements help to break up an otherwise
monolithic facade, providing amenities to residents, and be sustainable solutions in
reducing solar heat gain. Another solution is to reduce the overall
usage of glass in building envelopes, and eliminate glass “fly-through” conditions. This doesn’t mean we have to go back to
designing concrete bunkers or windowless facades. A building with a 25-40% window area relative
to other surfaces is generally considered to be effective in reducing bird fatalities. A low window to wall ratio can also improve
the energy performance of the building by reducing heating and cooling needs. All these glass and lighting strategies of
course should be used in combination with each other, and to the extent necessary that
does not compromise other important design considerations including access to natural
light, energy requirements, and cost. Over 50% of the world’s population now live
in urban areas and the UN estimates that by 2050, that percentage will grow to 66%. This is not necessarily a bad thing. Urbanization have open up a lot of economic
opportunity for people all over the world. And in many ways – high urban density can
result in less energy use per capita – resulting in more sustainable outcomes. But it’s important for us to be aware of
the ecological impacts of our growth and how the continuous encroachment and fragmentation
of natural wildlife habitats can be detrimental to human health and well being. And it’s important to keep in mind that
– practical, economical and sustainable solutions are out there. We just have to be aware and diligent enough
to implement them. Thank you so much everyone for watching and
thank you Sheryl for your help with this video. Sheryl has her own channel – The Roving Naturalist why don’t you tel us a little bit about your channel? Sure! So on the Roving Naturalist, I want to answer
all the questions you never knew you had about how humans and the environment interact. I’ve done videos on animal imagery in gargoyle
sculptures and how the border wall in between Mexico and the United States might be affecting
wildlife. If these topics sound interesting to you,
come check out my channel. The information will be somewhere over here. Awesome thank you so much and bye!

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