There are many theories for why birds fly into the glass but the reasons often given do not take into account the life of the bird or its view on its surroundings. So in this post, I will try and provide a few reasons as to why people ask the question, why cant birds see glass.
Birds can see glass but they may fly into it for a number of reasons, here is a list:
- They see a reflection of the sky or trees and fly towards it
- There is nothing in nature that looks the same as glass
- A scared bird will dart for cover and may fly into the glass in panic
Window collisions
Many of us may have experienced the sound of a sudden and unexpected thud on a window or door. Unfortunately, in most cases, this is likely to be the sound of a bird colliding with one of your windows or patio doors. The popularity of large picture windows, patio and bifold doors has led to increased bird-window collisions.
Although wild birds could have collided with your window while in panic, the RSPB believe that it is more likely to be through seeing a reflection of the sky and trees in the glass. While in this freight state, they are likely to see the reflection and decide that they can see a way through to safety, the result of which can be very distressing for both the bird and any person finding the bird.
Double glazed windows seem to be present an even greater danger than single glazed varieties due to the cleaner reflection they give off. If a collision does occur the bird is very likely to have suffered a concussion. A bird’s flight will inevitably mean that any collision will be head-on, leading to internal injuries. Broken wings or legs are relatively rare, but head injuries can be fatal.
What can you do if a bird collides with your window?
If you come across a bird that has been in a collision with glass, you should first monitor the bird from a safe distance for a short time. Often, birds will remain extremely still through shock and avoid drawing attention to themselves while in a vulnerable state.
If the bird is still alive, they recommend that you provide the bird with a dark, safe place where it can recuperate. The birds’ recovery should only take a couple of hours, and if the bird does not recover, it will likely die from its injuries.
Wild birds have exception vision
You could be forgiven for thinking that one of the reasons for a bird colliding with your window is that they cannot see very well. This is incorrect as the majority of UK wild birds have exceptional eyesight.
If you take a moment to watch birds in flight, you will no doubt have noticed their skill in being able to twist and change direction in an instant quickly. Flying in and around tree branches requires a great deal of skill and precision, and poor eyesight would make this very difficult indeed. In the bulk of wild birds, their large eyes take up most of the space in their skull. Even more so than their brain does!.
Birds eyes are also tightly packed into their heads which means they must turn their heads rather than just their eyes. Birds of prey have many more light receptors than humans which means that their vision is also enhanced. These birds of prey may have 8 to 10 times father vision than us with the ability to spot prey kilometres away.
Having their eyes located on the side of the head also provides wild birds with a fantastic wide field of vision. For example, a pigeon can see 320 degrees without even beginning to turn its head. This might go some way to explaining why they spot you and take flight before you even get a chance to sho them away from your prized cabbages!.
Other birds such as woodcocks have their eyes located at the rear of their heads. This enables the woodcock to continually watch for danger while their head may be down searching for food.
Natures Hunters
As with humans and many other animal species, birds of prey, including owls, all have their eyes facing forwards. This provides a distinct advantage for hunting compared to other species in the form of binocular vision. Binocular vision enables hunters to judge distance exceptionally well, an essential requirement if you are hunting prey.
Owls are the experts when it comes to nocturnal hunting and are usually active at dawn and dusk. One interesting fact that I have learned through my research is that the distinct storybook depiction of ‘Twit Twoo’ does in fact from both male and female tawny owls. The female being responsible for the ‘Twit’ and the male for the ‘Twoo’.
If you are out and about in the countryside or are lucky enough to live near a roosting couple. You may want to listen out again this August.
How can you prevent birds colliding with glass?
Homeowners can dramatically reduce the bird strike risk by making glass more obvious for birds to see. Fixing something to the glass can break reflections and give an early warning to birds. This could be a simple sticker or piece of paper placed on the glass.
You can take this a step further by ensuring that the paper affixed is an unusual shape, such as a moon or star. This will further help wild birds as they are unlikely to come across this shape in their natural environment. Other possible solutions include adding a one-way transparent tint to the glass and using external sunshades or awnings.
For most UK garden birds, the sight or silhouette of a bird of prey will almost definitely make them change course. Adding an image of a falcon or a hawk to the window should have the desired effect!
If you are not keen on adding stickers or random pieces of paper to your window, another more expensive solution is vertical blinds that continue to grow in popularity as luck would have it. These blinds offer an excellent method of deterring birds from using your windows as part of their flight plans!
Removing feeding stations from around the house’s proximity can also significantly reduce bird collision, a simple but effective approach.
Of course, these suggested methods may reduce bird collisions’ risk, but no method is full proof.
Old vs new windows
Keeping wild birds from flying into your windows is certainly one challenge, but another is deterring them from taking a closer interest in your frames!. For many of us, the older style wooden, putty sealed windows have given way to new modern UPVC versions. However, thankfully there are still a considerable number of beautiful old buildings with the older original windows.
Although these look beautiful to humans, they can also attract some unwelcome guests. In truth, it is not so much the window that is so attractive but that of the window frame putty.
The biggest culprit by far is that of the tit family who can become very interested in these frames around autumn and winter. On occasion especially during flying ant season (July/August), birds can appear to take on some strange behaviour. The abundance of food literally flying around them, often results in birds appearing to hop into the air, jump against walls, window frames and ledges searching for an easy meal.
In these later months of the year, the tit family is known to attack this older style of window frames searching for insects hidden in the rotting wood. It is also believed that another possible reason could be the desire to obtain linseed oil/fragments that are mixed into the putty. Although the precise cause is unknown, it is likely to be the tits desire to increase the mineral content that is missing from its diet.
Solutions to deter your local tit family from attacking your window putty include, adding fabric sealing strips to the frames which cover the putty entirely or to use special paints that aim to deter them. A product called ‘Arbolite‘, a synthetic putty has had many reported success stories and maybe worth a try if you are suffering from this problem.
The RSPB has also suggests brushing your windows with a solution of aluminium ammonium sulphate. The solution is harmless to the birds but is distasteful to them.