SCOTT SHALAWAY A pain in the glass

Thump! Another feathered body slammed into the porch window. It's a sickening sound I hear almost daily. Yesterday it was a junco.
Often the bird flies away, seemingly unhurt, but I wonder how many survive long enough to totally regain their senses. Many birds die instantly from these collisions.
Poorly studied
Though the threat that windows pose to backyard birds is common knowledge among those who feed birds, bird-window collisions have been poorly studied. Ornithologist Daniel Klem, Jr., however, has studied bird-window collisions for years. He concluded that birds are incapable of perceiving glass as a barrier. So wherever birds and windows occur together, collisions are inevitable.
In a telephone interview, Klem identified two types of windows that deceive birds. One appears invisible and creates a "see-through" effect, espec ially if there is an open window on the other side of the room that creates the illusion of a passageway through the house. The other type, strongly reflective windows, mirrors the outside habitat. In both cases birds cannot perceive the glass and attempt to either fly through the glass to daylight or into the vegetation reflected by the glass.
Other factors
While some birds may accidentally fly into windows during normal flight, other factors contribute to most collisions. Some birds, such as accipiter hawks and ruffed grouse, are at risk because of their habit of flying through restricted flight lanes in dense vegetation. Accipiters chase smaller birds through wooded areas, and grouse routinely fly through dense forest understory cover. In both cases these birds are guided by bright areas ahead that indicate open spots in the vegetation. Bright spots behind or reflected in glass create the same impression.
Most other victims are usually in some way distracted -- they may be escaping danger, involved in a chase, under the influence of alcohol (as when waxwings eat fermented berries), or disoriented by unusual weather or lighting.
At first, bird-window collisions may seem a trivial problem. But 40 million Americans feed birds in their backyard. If each records only one window strike per week (a conservative estimate based on my tally of several each day), it's not unreasonable to assume that a staggering number of birds may die at windows annually. The number certainly reaches into the tens of millions.
Indiscriminate killer
Furthermore, glass is an indiscriminate killer. It doesn't take just the old or sick. Young birds and healthy adults are equally vulnerable. Here are a few suggestions to reduce window strikes around the house.
Move feeders close to windows (within a foot or two) so birds can't build up lethal momentum if they do hit the glass.
Alter the appearance of transparent windows by covering the surface with objects spaced less than four inches apart. Strips of cardboard, paper plates, mobiles -- anything that makes the window more visible will suffice. This is the theory behind hawk silhouettes.
Cover problem windows with fine nylon netting.
Keep drapes closed and lights off to reduce the effect of a see-through passage behind the glass.
If you've tried these suggestions and birds still crash into your windows, I recommend two commercial solutions. For complete coverage of entire windows, try a Bird Screen (starting at $20; www.birdscreen.com; 717-445-9609), a flexible barrier placed on the outside of the window. It is effective, but expensive if you try to cover every window.
Desperate measure
A simpler, less expensive solution is a new product called Feather Guard ($6.99; www.featherguard.com; 800-879-2473). Conceived out of desperation by a New Jersey birder named Stiles Thomas, Feather Guard is simply a series of brightly colored feathers (dyed poultry feathers) fastened to a length of fishing line. Attached to the window pane with small suction cups, the feathers' color and motion warn birds away from the glass. Plus birds avoid loose feathers because they associate them with predators and danger. Feather Guard has been field tested for three years and significantly reduced window strikes.
sshalaway@aol.com