Clever, crafty crows quickly “wise up” that the anecdotal garden mannequin, however fearsome in appearance, never moves and therefore must not constitute a threat to their well-being, said Linda Tschirhart-Hejl, wildlife biologist with Texas AgriLife Extension’s wildlife services. University studies have shown that the traditional scarecrow frightens crows for a few hours, or possibly for a few days.
“It’s just that most birds - when you leave something out there and never change it over a period of time - become very used to it and, basically, it defeats the purpose of the scarecrow when they are sitting on it,” she said.
Crows like to feed on newly planted seeds, but pecans are a favorite. Thus, unless the gardener or nut producer stakes out his scarecrow on a hay bale and moves it around the garden on a regular basis, chances are it will become nothing more than an ornament.
Scarecrows in one form or another have been farmland fixtures for at least 3,000 years, said Jon Gersbach, Texas AgriLife Extension county agent for ag and natural resources in Milam County. They debuted along the Nile River to protect wheat fields from quail. Ancient Greeks patterned their scarecrows after the mythical Priapus, described as the “very ugly” son of Dionysus and Aphrodite. In the annals of scarecrow history, field marionettes have been made to smell bad or look horrible. Some were made with animal skulls; others were designed to look like witches.
He said today’s technology relies on movement, light and noise to be effective in chasing away avian pests. This is not a new idea; Medieval Britons employed young boys to chase and toss stones at birds.
Traditional scarecrows are more common now as autumn decor than as bird chasers, Gersbach said
“It’s kind of whimsical as a garden addition,” Gersbach said. “It’s not there because it helps in the garden.”
Scarecrows are part of the scenery at specialty farms, and are a tradition in some families.
Merchants offer a variety of high-tech scarecrows on the Internet and in horticulture catalogs, but they all incorporate the same basic tools: movement, light and noise, Gersbach said.
“It’s not the lowly scarecrow with its pumpkin head, flannel shirt and overalls, it’s now sophisticated,” Gersbach said. Bird scarers, such as owl and snake replicas, used to chase avians from public buildings but are only effective if they are regularly moved around, he said.
Scarecrows have all but disappeared from the agrarian landscape primarily because of cultural changes, and because “people tried it and it didn’t work,” suggested Ms. Tschirhart-Hejl.
Farmers, fruit and nut producers use more sophisticated means to heckle annoying crows, she said.
High-tech crow scarers can range from dangling aluminum pie pans and computer disks from fishing cord, to regularly moving a tractor or pickup around the field. There are scarecrows that shoot water at birds, propane-powered scare guns and the ever-effective shotgun blast in the air. Before shooting, however, make sure no protected species of birds are in the firing line, Ms. Tschirhart-Hejl said.
No scarecrows in the world are effective unless “you show them you mean business,” Gersbach said.
“Eventually, they will get wise, even if it’s a propane gun discharging every 15 seconds or so. These work good until they get used to hearing the noise,” Gersbach said.
Retired county agent Bill McCutchen, who works as a consultant to pecan growers, said the orchard combo of a propane gun and moving farm machinery and vehicles have been effective as scarecrows.
“Scarecrows? I never did use them. I had the idea they weren’t all that effective because crows get used to stuff and you have to change things around,” McCutchen said.
In home gardens, where mockingbirds like to peck ripened tomatoes, McCutchen found red Christmas balls placed on tomato bushes to be effective.
“They would peck on those and decide there was nothing there,” McCutchen said.
For home gardens, nets also are effective in keeping birds from pecking tomatoes. Crows are not the biggest pests in the home garden, McCutchen said. It’s mostly mockingbirds, blue jays and rabbits.
Has humankind developed a better scarecrow?
“No,” says Ms. Tschirhart-Hejl. “It all goes back to the fact that birds get used to everything. Usually with bird control, you use two to three different things. Even if you take the traditional scarecrow, move it three rows over, two rows back and change the color of its shirt every other day. It’s more effective than doing nothing at all because that object is moving.”
