Ruby-throated hummingbird John L Richbourg

Birds and Buildings

The Issue


FLAP bird fatalities layout; CREDIT: Kenneth Herdy

Year-round, migratory birds face huge challenges to their survival every day. Most threats are caused by humans, the greatest being the loss and degradation of habitat due to development.

After habitat loss, the dominant threats to birds are collisions with glass windows and predation by domestic cats. Professor Daniel Klem of Muhlenberg College in Pennsylvania has been studying the issue of collisions with windows for more than two decades and is the world’s foremost expert on the subject. He estimates that at least one billion birds die from building strikes each year in the United States. FLAP estimates that in Toronto alone at least one million birds strike buildings annually.

Most bird building strikes occur during the spring and fall migration. As most of Ontario’s birds are migratory, this means that a large proportion of our bird populations are vulnerable to the threat of building strikes.

Human-caused Annual Bird Mortality in the United States

Cause

Number of Deaths

Building window strikes

1 billion

Cats

Hundreds of millions. A study in Wisconsin estimated that domestic rural cats kill about 39 million birds annually in that state alone.

Transmission lines

174 million

Pesticides

72 million

Cars

60 million

Communications towers

Up to 50 million

Oil and waste water pits

Up to 2 million, mostly in western states

Oils spills

Hundreds of thousand depending on timing and severity of spills

Wind turbines

33,000 (will increase with the rapid increase in wind energy generation projects)

Source: U.S. Fish & Wildlife Service (2002)

Why Birds Strike Windows

Birds strike buildings during the day and at night. Extensive night lighting of tall structures may cause night-migrating birds to hit the buildings, often fatally. Birds use the stars and moon to navigate and may mistake the glow from towers as normal features of the night sky. This draws them towards a maze of city buildings. Artificial lighting is especially confusing to birds on foggy or rainy nights or when cloud cover is low and birds migrate at lower altitudes.

During the day, especially at first light when daytime migrants are most active, tinted, mirrored or clear glass poses a major hazard as it is invisible to birds. Window glass reflects the sky or images of trees and shrubs that may be planted around buildings. Birds will fly towards what they perceive to be habitat to rest and feed.

In the case of all-glass structures such as linkways that connect large buildings, birds will see right through the glass corridor to the other side. If this is an area such as a courtyard with natural features, they will head straight for it. Birds may even be attracted by large plants inside a building if they are placed by windows.

The Solution

Most public awareness of bird collisions has centred on night time collisions and campaigns to get owners of tall buildings to turn lights out at night. To learn more about these initiatives, visit the municipal government’s Lights Out Toronto Campaign.

However, most people are less familiar with the issue of daytime strikes, even though this is when the majority of incidents occur. Most bird strikes happen at lower level windows, up to 12 metres from ground level.

The solutions are straightforward. Remove all vegetation from around reflective windows. Apply specialized film to lower level windows to enable birds to recognize windows as an obstruction or apply specialized netting to prevent collisions.

The City of Toronto has taken action for new building construction. Its Green Standard requires developers to mute external reflections or apply density patterns to windows between 10 to 28 centimetres apart for the first 10 to 12 metres above grade level, where 90 percent of bird collisions occur.

To date there has been no requirement for owners of existing buildings to retrofit to minimize the risk for bird collisions. Voluntary action has been taken by a few buildings with great success. The Town of Markham applied a special window film to one of its strike-prone municipal buildings and is reporting great success in eliminating bird strikes.

But voluntary action isn’t solving the problem. Though building owners are well aware of the issue of window hazards, excuses such as cost or aesthetics prevail. And birds continue to die.

What Ontario Nature is Doing About It


Whip-poor-will before release; CREDIT: FLAP

We are working with lawyers from Ecojustice in a private prosecution against Menkes Development Ltd., the owners of the Consillium Place complex in Scarborough.

FLAPs monitoring and retrieval of dead and injured birds has highlighted Consillium Place as Toronto’s deadliest building for birds.

The purpose of our action is to demonstrate that there is a requirement under law (the Ontario Environmental Protection Act and the Ontario SPCA Act) to ensure that buildings are retrofitted to reduce window hazards. We also believe the death of any bird listed under the Ontario Endangered Species Act is a prosecutable offense. Two whip-poor-wills (threatened species) died when they struck a building in downtown Toronto this spring (2010).

By forcing action on this issue, many of the one million annual casualties in Toronto may be avoided. There is also international interest in our case. A win in Ontario could have a larger ripple effect, benefitting birds in North America and elsewhere.

Check out ON Nature magazine’s article on bird strikes, City Lights.

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Fact Sheet

- After habitat loss, the dominant threats to birds are collisions with glass windows and predation by domestic cats.

- In Toronto alone, it is estimated that one million birds die in collisions with buildings each year.

- The solutions are straightforward. Remove all vegetation from around reflective windows. Apply specialized film to lower level windows to enable birds to recognize windows as an obstruction or specialized netting to prevent collisions.

 

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