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!