Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: SUNDAY, January 5, 1992 TAG: 9201010219
SECTION: EXTRA PAGE: 5 EDITION: METRO
SOURCE: The New York Times
DATELINE: LENGTH: Medium
WINDOWS ARE DANGEROUS TO BIRDS
The windows that bird lovers use to see who feasts at backyard feeders can be hazardous for their feathered friends, a survey has found. When startled by a potential predator or chased by a more aggressive diner, birds at feeders often beat a hasty retreat headlong into windows they mistake for a clear path to safety.Though some are only temporarily stunned by the collision, for many others the feeder feast becomes a last meal. During the winter of 1989-90, the Cornell Laboratory of Ornithology asked the 5,500 participants in its home-based FeederWatch program to record all incidents of birds crashing into windows.
Nine percent of FeederWatch participants recorded evidence of one or more fatal window collisions, for a total of 945 birds. Dr. Erica Dunn, who directs the project, said that no doubt there were other fatalities, since many stunned or dead birds become prey for other animals.
Sixty-six species were included in the tally of fatalities, most of them common visitors to winter feeders. Pine siskins, goldfinches and dark-eyed juncos accounted for the highest percentage of kills, followed by cardinals, mourning doves and house finches.
Some birds seem more savvy about avoiding the hazards of glass-pocked houses. House sparrows, red-winged blackbirds, starlings, blue jays and chipping sparrows were less vulnerable to window kills than their numbers at feeders would have predicted.
Panic flights of birds trying to escape predation by raptors accounted for 16 percent of reported window strikes. In other cases, birds flew into windows after being frightened by loud noises, passing cars or the arrival at the feeder of a large competitor.
Dunn explained that birds sometimes crash into windows because the glass reflects outside vegetation and the birds think they are heading for a protective bush.
In other cases, two windows may be so aligned that they appear to form a clear path through the house to the trees or shrubs beyond. Surprisingly, houses with lots of nearby vegetation were more likely to report large numbers of fatal window collisions.
Based on the FeederWatch study, Dunn believes that 95 million birds die in window kills each year.
A number of devices are available to keep birds away from windows or make windows more visible or less reflective, including hawk silhouettes, wind socks, streamers, one-way film or tinting and screens. However, Dunn said, little research has been done to show whether the devices work.
Four of the study participants who had severe window-strike problems reported that plastic garden netting installed about a foot away from the culprit window greatly reduced casualties.