So we have discussed the effects of artificial light on birds. We can see there are some adverse effects like circadian clock disruption, behavioural changes, disorientation during migration, etc. However, an even more direct effect of artificial light is window collisions.

Window Collisions and Welfare Implications 

Imagine: You are a migratory bird flying through the big city. You see a beautiful tree to take refuge, however there are all these bright lights around confusing your path. You end up flying for the tree, only to discover it was a reflection of the tree in the glass window. You die on impact.

Source: http://erenweb.org/new-page/bird-window-collisions-project/

This grisly scene is one of the leading causes of bird death in the world, second only to cats. In the United States, an underestimate of 1 billion birds, and in Canada upwards of 42 million, are killed annually by window collisions (Klem 2015). Dr. Daniel Klem Jr. has been a investigating the issue of bird window collisions for a number of years, and raises important issues concerning bird welfare concerns. Birds cannot discern flat-glass windows from the rest of their environment due to their seeing in ultraviolet rays. Glass buildings of all shapes and sizes pose lethal threats to birds, but there are solutions available.

Short-term solutions include window decals, netting, shutters, blinds placements, etc. Long-term solutions include ultraviolet decals, designing bird-safe buildings, and Leadership in Energy and Environment Design (LEED) certification for bird-safe buildings.