1. Reflection: Glass reflects light, and birds may mistake it for water or open sky and try to fly through it. It's especially common for birds to collide with windows during cloudy days or heavy rains, when they get confused and fail to see the obstacle.
2. Territorality: If the bird is a territorial species, it might be seeing your window as an intruder in its territory and feel the need to defend it.
3. Attracted to Insects: If your window is near a source of insects, the insects may be the actual target of the bird's attention, and the bird might be trying to catch them as they flutter near your window.
4. Curious and Investigative: Some birds are simply curious and might be checking out your window to try and figure out what it is.
5. Seeking Shelter: If the bird feels threatened, it might try to seek shelter inside the building, and might mistake your window for an open entrance.
It's important to prevent birds from repeatedly hitting windows, as these collisions can cause injuries and even death to the birds. To do so, you can consider the following steps:
1. Install Window Decals: Apply decals or stickers on your window that may discourage birds from colliding.
2. Use Curtains: If possible, keep your curtains or blinds partially closed to break the reflection of the sky or anything that may confuse birds.
3. Bird Netting: Installing bird netting over the window can help prevent birds from reaching your window.
4. Bird Feeder Relocation: If you notice the bird is primarily focused on insects, try moving your bird feeders away from the problematic window.