An estimated 100 million birds die each year by accidentally flying into windows on buildings or homes [source: Mass Audubon Collisions]. These accidental collisions are messy and unpleasant, but not necessarily unlucky – except for the poor, unfortunate bird throwing itself against the window. But what does it mean when a bird intentionally attacks your windows, pecking away at the glass? According to superstition, a bird pecking at the window means death for someone in the home [source: The Diagram Group].
Fortunately, ornithologists have a slightly more scientific take on this behavior. Birds are territorial, and this aggressive pecking is simply a way of defending their turf from what they see as a rival bird – really their own reflection. It's most common among robins, cardinals and other birds that tend to make their homes in areas populated by humans. If you can simply wait out the pecking, it should stop by the time breeding season is over. If not, consider covering windows with a clear sheet of plastic to help obscure the bird's reflection, making it less likely to peck [source: Mass Audubon Collisions].