Certain bird species are more vulnerable to collisions due to various factors such as habitat, migration patterns and behavior. For instance, migratory songbirds; like warblers and thrushes, are particularly susceptible to collisions during their long journeys. Studies have shown that these species often mistake reflections in glass windows for open sky or suitable habitat, leading to fatal impacts.  There are also documented examples of birds striking glass windows in a territorial dispute, assuming their own reflection is a threat.

Unfortunately, the most alarming thing in this discussion is that only about a third of window collision victims survive the impact.  Even if able to fly away, birds are left with concussions, brain swelling, broken bones and/or flight feathers, internal bleeding and shock.  Instinct will prompt them to take cover if possible, where they quietly succumb to their injuries, or are vulnerable targets for predators.

As urban areas expand and skyscrapers become more commonplace, the risk to birds increases. Research indicates that taller buildings with extensive glass surfaces pose a greater threat to birds flying at higher altitudes. However, the higher overall mortality numbers occur in shorter buildings, such as low-rise apartments, commercial buildings and residential homes due larger numbers of these types of constructions in addition to the prevalence of vegetation at lower levels.