Birds and marking the windows

By making the windows more visible to the birds you can prevent birds flying into them


Birds do not realise that it is impossible to fly through glass windows. In the worst case, flying against the glass at full speed can be fatal to the bird. To prevent this from happening, it would be wise to mark large windows and glass surfaces for birds.

KARDIN AITAB. Erksamavärvilise kardina või rulooga kaetud aknasse lind ei lenda. Foto autor. Margo Pajuste
A CURTAIN HELPS. A bird does not fly into a window covered with a brightly coloured curtains or blinds. By: Margo Pajuste


More than a few of us have probably found a stunned or even a dead bird by the window, who has been injured when flying against the glass. This is especially easy when the glass surfaces are large, located high, and are very transparent.


High-rise buildings, glass bus stops, and noise barriers, as well as large windows in new houses, which are sometimes located on opposite sides of the house so that you can see right through the building, are dangerous for birds. The birds think that there is enough room for flying on the other side of the glass as well, and when they fly against the transparent surface, the bird mostly injures their neck and/or head; instantaneous death is caused by a fracture of the cervical vertebrae. Hundreds of birds can be injured this way during their migration, when deaths due to flying into glass are also quite common [1].


However, the reason for birds flying straight into glass surfaces is often that a bird feeder with food is located right by the window. A bird flying fast towards the food does not perceive glass as an obstacle, and even if it does not perish, the collision easily results in hypothermia from lying on the ground in winter. To avoid such collisions, the bird feeder must be placed away from windows.


Birds flying into your windows can be prevented by making the glasses more visible to birds – for that, you have many options and even technologies to choose from.


Recommendations for avoiding birds flying into glass surfaces:

  • Pull a blind or a curtain in front of the window.
  • Glue paper decorations on the windows or mark them with masking tape. It has been found that markings that are glued on the outside are the most useful. The markings could be colourful.
  • Markings should be placed closely together. When marking a glass door, one coloured dot is enough for a person, but birds need more markings to notice the glass – birds are used to flying through very small openings. It is recommended to place the markings with a distance of 10–15 cm [2].
  • Although it is recommended to use stickers of the silhouettes of various birds of prey, their effectiveness has not been proven. At the same time, they are definitely more useful than not marking the glass at all.
  • Turn off unnecessary lights in the dark. At night, birds fly by the stars – they are confused by artificial light, so they can fly into the glass.
  • If, for aesthetic reasons, you do not wish to stick anything on the windows, there are also stickers and tapes that reflect ultraviolet light and are invisible to the human eye, but visible to birds [3].
  • Permanent solutions are low-reflectance glass and anti-reflective film covering the windows.
  • Special bird-friendly types of glass (such as Ornilux glass) have also been developed.

However, if a glass accident has still occurred and the bird is stunned by the shock, you should move them to a safe place, protected from predators. There the bird can recover peacefully and go its way after a while.




Last modified: 17.01.2022