Bird Buddy Blog

Window strikes: why they happen and what we can do to stop them.

Courtesy of Flickr

It is no secret that humans have contributed to a huge decline in bird numbers over the last 150 years. We’ll take a look at some of the things that led to these declines, and what we can do to help numbers recover.

The story of our influence on the natural world has many chapters, and when the larger picture becomes too overwhelming, it is sometimes better to focus on one piece at a time, and soon you begin to see that simple behaviours can be adjusted. Counteractive methods soon become easier and more enjoyable, and the results more rewarding. Birds currently face a myriad of issues and we’ll take a look at those that are within our control as individuals over a number of articles. We wouldn’t want to bombard you with too many negatives at once!

That struck en masse, my window glass

The first issue is glass collisions or window strikes. This is one of the easiest problems to rectify and we’ll tell you about steps you can take to protect the birds nearby.

It is no secret that humans have contributed to a huge decline in bird numbers over the last 150 years.

Windows either appear invisible to birds or reflect the world outside back at them, making them think there is somewhere equally as pretty as your garden to fly to. At night, if we have left the lights on and the curtains or blinds open, they will also look like a destination. So not only can birds accidentally fly into windows by not seeing them, birds will also deliberately fly at them. How many birds a year does this kill?

There has been no quantitative study performed to find this out yet, but there is a much-quoted figure of 1 billion birds a year dying from window strikes in the US. Frustratingly, this figure was plucked from the air in the 1990s by a biologist called Professor Daniel Klem. Using census data, he first calculated the number of buildings in North America. He then assumed a rate of between one and ten birds would be killed hitting each one of those buildings a year. Prefacing his result with the words that there are no hard facts available, he published a figure of between 97.6 million to 975.6 million birds dying from strikes each year. The second number was taken and subsequently rounded up in the media to 1 billion, becoming the most often quoted number today.

However, it is widely accepted that this estimate is not only probably true, but quite possibly an underestimate. Small-scale research has found that a third of ringed birds returned dead have injuries of the kind sustained in window strikes. Bird conservation groups are now trying to work with construction companies urging them to incorporate materials and consider designs that actively deter birds, such as this one in Toronto. Just one multi-storey building there regularly found around 100 dead birds on the pavement outside each year, so it would be very remiss to deny that glass-fronted skyscrapers the world over have an effect on bird populations, considering many of those structures are in the middle of migratory flyways.

Home help

Anyone who has ever been unfortunate enough to hear the sickening thump of a bird hitting a window will know the rush of shock and sadness that comes with the realisation of what has happened. Often, the bird is just stunned and will sit on the ground for a while until it has regained its senses and will fly away, but alas this doesn’t necessarily mean that bird will be OK. Internal bleeding can set in later and sometimes they will just die elsewhere from their injuries.

This is possibly one of the easiest problems to rectify.

So, what can you do? Start by identifying which of your windows are likely to be a problem. If it’s possible, go outside and look at them from different angles. If you can see trees or the sky reflected in them, so can the birds. Look for windows that are right-angled to each other as well. Having feeders near windows is now thought to be OK, with the reasoning being that birds will stop at the feeder, and if they suddenly set off from it perhaps to escape a predator, they won’t have built up enough speed to cause much damage if they go in the wrong direction.

There are many products on the market these days called window decals, which are essentially designs that you can smooth onto the outside surface of the window using a damp cloth, and this will break up the overall appearance of the glass. You can also buy opaque or transparent film often with fun and attractive designs that will scatter the reflectivity of the window, but you can still see out.

If you have an artistic streak or just want to mess about with paints, you can have a go at a design yourself using tempera paints, which won’t get washed off by rain but can be easily removed with a cloth. Remember to space out your designs and decals so you can still see out, but close enough together so that a bird couldn’t “fit through” if it were flying towards the window.

A similar effect can be achieved by hanging weighted or connected strings or cords from the top of your window in vertical lines. This is called a zen curtain and there are DIY videos online, some with affiliate links to purchase ready-made ones.

Externally fitted window screens or fine netting / insect mesh can provide a barrier between the bird and the window glass itself, with the principle being that the taut mesh will help the bird bounce back from the surface like a trampoline, reducing the impact by spreading the force through the small gaps of air in-between. Netting or mesh should be at least 3” away from the surface of the glass to provide enough space for the rebound.

If you happen to be redesigning your home or even working on a new build, there are many long-term solutions you can incorporate right away, such as latticed windows, fitting the windows at a slight angle towards the ground to as to reflect that and not the sky, or choosing patterned or frosted glass.

Wind chimes, sun-catchers, dreamcatchers, crystals on strings, pretty shiny things that move and catch the light; birds will steer clear of unknown or noisy objects.

Making your home safe against bird strikes is simple and usually inexpensive or free.

Remember, at night, either at home or at work, especially if you work in a high office block, turn off your lights. Studies have shown that over half of the fatalities that befall migratory birds are due to distraction and flying towards lit buildings.

Dazed and confused

What should you do if you find a bird that has been in a window collision? Firstly, examine it for any obvious external injuries. If you see none, and the wings are not bent at an angle but held as you would expect against the back, leave the bird alone but stay close and watch it, making sure there are no predators nearby like cats or dogs. Chances are it is just dazed and will recover. If it is just sitting there after 20 minutes and it allows you to approach, scoop it up in a soft towel or using gloves, and place it into a box, somewhere it can be comfortable in the dark. If it is cold outside, take it indoors if you can, but somewhere quiet. Don’t try to give it food or water but let it be. The dark and quiet should calm it down and usually within a few minutes you should hear some movement. Take the box back outside if you’ve moved indoors, and then open the box and stand back. If it flies off, great. If it doesn’t, repeat this process and if after a couple of hours, you still have a bird, then it’s time to get it seen by a professional.

If there is obvious injury you must take it to a vet or wildlife rehab service right away. Any broken bones must be seen quickly or that bird’s life is effectively over. Transfer the bird in the dark box as before.

Making your home safe against bird strikes is simple and usually inexpensive if not free, and even though you may think you are but a tiny cog in a huge machine, the steps you take will not only have an enormous ripple effect on your local bird population, but the world’s, too.