Put Up Your Guard

You’ve done it—you created the perfect outdoor oasis. Now lilting birdsongs are your alarm clock; your double-decker birdhouse seldom has a peak-season vacancy; and “the restaurant”—otherwise known as the feeding station—practically requires a reservation. Things couldn’t be better. Then disaster strikes: a sobering thud against the window; a hawk with a just-fed goldfinch in its talons; a cat with a tuft of feathers dangling from its mouth; a house finch with conjunctivitis splashing around the birdbath. How can you prevent such backyard blunders? Our expert ornithologist covers everything you need to know.

Windows

Collisions with glass are the single greatest threat to the birds visiting your yard. It’s not that birds have bad vision; an American kestrel, for instance, can spy an insect no bigger than a pea from 60 feet away and sees a broader range of colors than humans do. But glass presents a novel obstacle—a transparent, unyielding wall—and nothing in a bird’s evolutionary past has prepared it for such face-to-glass encounters. Windows kill indiscriminately, taking both healthy and ailing birds in every season, day and night. Researchers with the Cornell Laboratory of Ornithology’s Project FeederWatch found that window collisions might account for the deaths of between one and ten birds per building, per year. Daniel Klem Jr., an ornithology and conservation biology professor at Pennsylvania’s Muhlenberg College, estimates that as many as a billion birds die this way each year in the United States. His research indicates that feeders placed within three to 30 feet of a window are especially dangerous, because this gives flushed birds enough distance to build momentum for a fatal crash.

Objects stuck to the glass are often considered an acceptable safeguard, but unfortunately, such decorations usually don’t work. Even the classic falcon silhouette sold for this purpose has next to no benefit unless the silhouettes are just two to four inches apart and cover most of the window. One promising new product is WindowAlert. Available with static backing, these decals, which come in leaf, butterfly, snowflake, or hummingbird shapes, effectively break up the large, reflective surface with a frosted-glass effect. To increase your chances of success, attach the stickers to the outside of windows. By putting them about three inches apart, you will create a nearly transparent, decorative look indoors while helping to break up the mirrorlike surface from the outside. The glass’s reflective nature can also be blocked with a one-way surface film, which masks the exterior with a solid silver-gray color that’s transparent from inside.

When birds repeatedly hurl themselves at the same pane of glass in spring and early summer, they are likely battling their own likenesses. This behavior arises from an attempt to chase a rival from a nesting territory. Try hanging mobiles, wind chimes, or Mylar streamers outside. (Objects attached or suspended inside windows offer little benefit.)

Windows that result in chronic collisions can be fitted with mesh netting. Fruit tree netting (available at most garden shops) is ideal. Stretch the netting over the outside of the window, securing it in place with molding, or ask a local screen and glass shop to make fitted screens with the netting. For smaller windows, one of the simplest solutions is to leave screens in place throughout the year. Commercial bird-bouncing devices are also available for large windows. One such drop-down screen is secured to the window with suction cups.

If a head-on collision with glass doesn’t do a bird in, other factors might. Stunned birds become more vulnerable to predators, and a feathered traveler with a concussion won’t likely have all the faculties it needs to fly and feed during an already arduous migration. (Find my tips for helping a stunned bird here.) If you haven’t yet witnessed a bird meeting glass, don’t assume that your windows are safe. Strikes often go unnoticed because scavengers like cats and raccoons make quick work of the feathered corpses. Look at your windows closely for telltale feathers stuck to their surface or the powdery outline of wings, and take the proper precautions.

Cats

Got a Sylvester stalking your feeder hoping to snag himself a Tweety Bird? Between 1970 and 1990 the number of domestic cats in the United States doubled, from 30 million to 60 million, according to the U.S. Census Bureau. Taking into account stray and feral cats, more than 100 million cats are likely prowling the United States. Although birds make up only about 20 percent of the prey killed by cats (mice and other rodents are mainly taken), felines kill hundreds of millions of birds each year. Many of these are migratory songbirds that are already under pressure from habitat loss and other threats, including collisions with buildings and cell phone towers. Most bird fatalities happen near homes, where house cats come and go and where birds are concentrated at feeders. Fledglings are acutely vulnerable, since some spend a few days on the ground before they can fly.