Knock on Wood

Scientists show what works—and what doesn't—
to stop woodpeckers from pounding on homes

By Pat Leonard

Downy Woodpecker

Photo by Evan Barbour

Woodpeckers are beautiful and entertaining—unless they're turning your home's siding into Swiss cheese. If the birds are looking for insects, the holes are small. If they're creating a nest cavity, the hole is much larger and causes even more damage.

"A Downy Woodpecker that could fit into the palm of my hand made it his mission to dig into my cedar siding for two months," says Phil Miller of Ithaca, New York. "There were showers of sawdust everywhere—and a fist-sized hole that went right through to the insulation." Miller is not alone. Woodpeckers cause millions of dollars in damage to North American homes each year.

Woodpeckers seeking food or shelter sometimes bore holes in siding. The study found that dark-colored wood is particularly enticing.

Photo by Paul Curtis

A Cornell Lab of Ornithology study surveyed 1,400 homes in the area around Ithaca to learn which ones were most enticing to woodpeckers. It also tested six common long-term deterrents to see how effectively each prevented woodpecker damage. The results were published in the August 2007 issue of the Journal of Wildlife Management.

"I learned a lot from these birds," says study author Emily Harding, who conducted the research as part of her master's program in wildlife management at Cornell. "They have a lot of personality, and a great ability to adapt."

It has long been known that homes that are badly infested with ants or carpenter bees are especially attractive sources of food. Exterminators often must be called in to stop the infestation. In addition, the study found that homes sided with vinyl or aluminum, or painted and sealed in light colors—such as white, yellow, blue, or other pastel shades—are less likely to get hammered than wood-sided or dark-colored homes. If new siding or insect extermination are not options, homeowners can try scaring the woodpeckers away.

Using shiny, reflective streamers that move with the wind is one of the most effective ways to keep woodpeckers from becoming home wreckers.

Photo by Paul Curtis

Harding says she and her team tested six deterrents: life-sized plastic owls with paper wings, reflective streamers, plastic eyes strung on fishing line, roost boxes, suet feeders, and a sound system that broadcasts woodpecker distress calls followed by the call of a hawk. Only the streamers worked with any consistency: the shiny coating and movement in the wind kept the woodpeckers at bay and completely eliminated damage at half of the 16 test sites.

"Birds are smart, and they get used to the other types of deterrents, even the distress calls," says Sandra Vehrencamp, a scientist at the Lab of Ornithology and one of the study's coauthors. "The sounds are obnoxious. Neighbors hate it—plus, it's just not effective at all."

"I've seen woodpeckers sitting right on top of sound devices as they played," says Harding. "I've seen them digging into houses with suet feeders a few feet away. I've recorded hours of videotape with not one woodpecker ever coming to tap—yet new holes would mysteriously appear."

Miller tried dousing the affected area with ammonia, hanging strips of aluminum foil, and dangling compact discs on strings. Each time, he says, the woodpecker moved to a new spot on the house—until one day it just disappeared.

"I'm knocking on wood that the problem may be solved," he says. "We haven't seen the woodpecker in a couple of weeks, so maybe we irritated him enough that he's pursuing other housing options for the winter." The bottom line: nothing works all the time.

"The homeowner needs to carefully evaluate deterrent devices, and not rely on anecdotal claims," says Cornell professor and study coauthor Paul Curtis. "Many of the devices simply have not been adequately tested under field conditions."

Vehrencamp used the tape streamers on her own earth-toned, wood-sided home and was pleased with the results. "It's a very simple, inexpensive solution. I would rather have these somewhat unsightly streamers on my house and attract the woodpeckers with suet feeders—they're wonderful birds, and I love seeing them!"

For permission to reprint all or part of this article, please contact Laura Erickson, editor, Cornell Lab of Ornithology, 159 Sapsucker Woods Rd., Ithaca, NY, 14850. Phone: (607) 254-1114. email: lle24@cornell.edu