DIURNAL COLLISIONS
		Objects in this mirror are more deadly than they appear How about bringing the issue a bit closer to home, you say. Sure, we know about the problem of night-migrating birds hitting lit towers and of course we're concerned. But what about the birds that hit the picture window in our living room or the patio doors at Aunt Mae's cottage or the shiny glass walls of the university building down the road? Okay, so we've only seen the evidence once or twice but we've heard that sickening thud a few times and the neighborhood is teeming with cats... 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.
	Tinted, mirrored or clear, glass is invisible to birds. If it reflects their natural habitat, the trees, shrubs or sky where they would normally take refuge from perceived dangers, chances are good they'll fly towards it. Their behaviour may be further influenced by other factors: the proximity of a tree to the window, the angle at which the bird sees the reflection, the positioning of a feeder. Another problem situation, one which FLAP members encounter often, is where a large leafy plant is placed inside a building and birds can see it clearly, but not the intervening glass wall. If they are in an alien environment (such as Toronto's downtown core) where a person walking by will frighten them, they're sure to head for that leafy plant. A panicked bird will smack into a window with greater force and often disastrous results. The same holds true in places where glass on both sides of a building creates the illusion of an unobstructed corridor. Birds will gather momentum as they prepare to sail through the perceived passageway. Not all birds are killed outright. (Dan found one of every two strikes to be fatal.) The survivors may be merely stunned, but if predatory animals (cats, dogs, hawks, raccoons, even squirrels) have learned to patrol the area for casualties, we may never see the fallen birds. Hence, the general perception that window kills are a rare occurrence. But Dan Klem, who has monitored various types of buildings in different settings, and conducted field and laboratory experiments to better understand the problem, believes that the much-publicized loss of birds to cats, oil spills and pesticide poisonings accounts for considerably fewer deaths than windows and glass walls. Seemingly innocuous structures such as houses take a considerable toll in birds. Add to that the fact that more and more buildings are constructed using reflective materials and you see why this becomes a serious concern. HOME