What do you see? A landscape? The marks on the glass, courtesy of the local birds and the weather? An interesting pattern? All of these? I see this more as an arrangement of shapes and if portrayed in paint it would resemble an abstract composition. This is another example of an abstract image in Nature.
The following images are obviously variations of the first, just to show two other ways of interpreting the composition.
Of course, there are many more ways of looking at the original image. It’s up to the artist to make up their own mind about what they see and how they wish to portray it.
This type of subject would suit acrylics and oil pastels, the latter being well suited to the textures that could be employed.