A walk into in a sliding glass door may elicited a “ye-ow” and perhaps something even a little more, shall we say, colorful?
Yet for North America's birds who are now packing their bags for their breeding ground exit to fly to their wintering homes, those same sliding glass doors are real killers.
So much so, in fact, that by the time all of those thrushes, sparrows, larks, robins, hummingbirds, cedar waxwings, woodcocks and other songbirds arrive in time for their Southern version of a mint julep, an estimated 300 million to one billion of them will not arrive.
Those figures tell the story of just how dangerous glass is to birds, something that many humans have a difficult time comprehending.
After all, while a person might explode into a blue tirade when he or she conks his or her head into well-cleaned glass nothing more than a temporary bruise or bump results.
“Without question, collisions of birds into glass is one of the most significant causes of bird mortality worldwide,” said Christine Sheppard, manager of the American Bird Conservancy's Birds Collisions Campaign.
Among the most vulnerable – or perhaps, most glass-accident prone – North American birds species are the wood thrush, the black-and-white warbler, the dark-eyed junco, the white-throated sparrow, the ruby-throated hummingbird, and the American woodcock, Sheppard says.
A major factor in birds dying by striking glass, Sheppard says, is the fact that many bird species migrate at night and through unfamiliar turf.
“Parts of the problem are actually simple to understand,” Sheppard says.
This simplicity, says Sheppard, is really an elementary deduction on the part of humans.
We, as humans (for the most part and usually, anyway), can deduce when a pane of glass lies ahead.
The give-away might be a window's frame or perhaps even a little bit of dirt or smudge on the glass, arresting our attention and thus avoiding a run-in, Sheppard says.
“Birds don't learn these cues so they take any reflection literally or else they try to fly through what they believe is transparent in order to reach something beyond,” she said.
Sheppard says she and others are working on ways to minimize the number of birds attempting to take a detour through a double-pane of Anderson glass.
Her efforts include bird-avoidance testing of various materials in an effort to find something that works for people as well as for the birds.
Nor are manufacturers of glass turning a blind eye to the issue, also says Sheppard, bringing into the equation experts who hardly could be said are bird-brains.
These experts are even poking into the realm of ultra-violet light, aware that while the human eye cannot see into this range, a bird's eye can. Or at least in some fashion.
“One commercially available product with a UV signature is virtually transparent, but only moderately effective,” Sheppard says. “However, this manufacturer – along with others – is working hard to perfect the technology.”
- Jeffrey L. Frischkorn