We heard the loud thud on the glass and wondered what had happened. Nothing was amiss outside but then we noticed the kitchen window; there was a large dusty mark in the middle of the large pane - a bird had flown into the window. Was it injured? We don't know but as there was no sign of a bird outside, it was apparently able to fly away.
The large, white, dusty spot in the middle is the body, while the wings are the diagonals. The wing tips, spreading into individual feathers, are clearly defined by the dust.
From FLAP (Fatal Light Awareness Program): "If you believe that windows in general pose a serious threat to birds, you're perfectly right. Daniel Klem Jr., a biologist at Muhlenberg College in Pennsylvania, conservatively estimates that every year over 100 million birds die as a result of hitting glass in the United States alone. Dan's studies show that glass in any form - large windows or small, in tall buildings or modest homes, even a car windshield - is a potential killer."