PopSci: “Glass windows are a marvel of human engineering–clear, nearly invisible sheets of sturdy material that let us bring natural light into closed structures. Yet beyond the walls of bright and airy buildings, windows become something else: A threat to wildlife.  Birds don’t understand glass. They haven’t been taught to recognize the structural cues indicating a pane is present, like a rectangular frame or door handle. Instead they often try to fly through it, seeing the open space behind a window as more habitat, or interpreting the reflection in the glass as reality. Don’t judge them too harshly for it, humans run into glass too. But for our feathered, flying friends, the consequences are much more severe.  Windows and glass buildings, particularly combined with the draw and disorientation of artificial light, kill a huge number of birds. And the problem is even worse than we thought. Past estimates of that morality are undercounts, according to new research. It might be tempting to assume that birds found stunned or injured after window collisions and brought to wildlife rehabbers are all making a full recovery. Instead, about 60 percent die–even under the best possible circumstances, receiving care and protection from predators, as outlined in a study published August 7 in the journal PLOS One.  Previous research has come to variable conclusions about estimated avian losses from building strikes. One of the most commonly cited figures, from a 2014 study, suggests that somewhere between hundreds of millions and one billion birds die from hitting windows each year in the U.S. alone. Yet this past analysis, and almost all other investigations of window mortality, relied solely on counting birds found dead next to structures. The new work goes a step further, assessing what happens to a subset of birds that survive the initial impact. Finding that more than half don’t make it leads to an unsettling and unfortunate revised estimate. “Well over 1 billion birds are dying each year in the United States” from building collisions, write the study authors…”