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The high-rise threat to birdlife

Contemporary architects just love glass and, to be fair, it is quite easy to see why. Glass makes the interior of buildings brighter and feel less claustrophobic, it also adds a twinkle to the cityscape. There is just one small problem with glass, though, and that problem is birds. Glass kills millions of birds every year, and as more buildings go up, so do bird mortality rates.

Of course, the higher the building, the greater the risk, especially for migratory birds that tend to fly higher than is usual. The problem is more pronounced at night time when the light from a building can be potentially more confusing for birds.

As an example, office workers arrived at their building (a skyscraper) to find 400 dead birds on the ground. The night before in Galveston, Texas, a large group of migratory birds had seemingly altered their flight path and 'ran' headlong into the high-rise.

Richard Gibbons, conservation director at the Houston Audubon, commented that "A storm was battering the city, which probably forced the birds to fly low. In the dark, they may have mistaken the skyscraper‘s lights for the sun or moon".

A problem a time of the day or night

Confusing lights aside, glass fronted buildings are a danger to our feathered friends but why do they hit them so frequently? It has been theorised that perhaps the birds simply do not see the glass, and there may be truth in that. A more popular theory is that a combination of reflections in the glass and items in the rooms beyond confuse the birds.

The theory goes that the bird sees a plant in the room and assumes that there is a way through the building. Reflections of the sky may be having the same effect on the birds. Whatever the exact reasons for the birds striking windows, there are things that can be done to help them and which have been shown to reduce the number of incidents.

Make flying safe again

We may not be able to stop window strikes completely, but there are things that we can do in order to dramatically lower the number of times of accidental collisions. Window stickers have been shown to be very effective in reducing window strikes, as birds see these as obstructions and so avoid the windows completely. This method is very effective on homes but is not practical for larger buildings such as skyscrapers.

Working on the idea that birds are able to see Ultra Violet light, German company Arnold Glass have developed a product with UV lines criss-crossing panes of glass. In subsequent tests, bird strike incidents were reduced by an incredible 75%.

These panes of glass look totally normal to the naked, human, eye but a bird sees an obstacle to be avoided. In fact, as Arnold Glass noted, Orb-web spiders produce a UV reflecting silk for the specific purpose of preventing birds flying into their webs.

Any architects making use of this or similar products in their skyscraper designs will find themselves with a lot of new feathered friends. Once more, high-rise office workers will be able to go about their business without jumping out of their skin every time a bird slams into their window.


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