Spring 2002 Table of Contents

It's crow time!

Fall and winter sets the stage for the rock-and-roll show of the backyard bird world: crows are seen in large, raucous flocks that roam widely and gather in trees in huge communal roosts at night.

Crows are not inherently bad birds, of course. They eat a lot of destructive insects, clean up carrion and garbage, and do not - contrary to popular opinion - have a significant impact on songbirds, which they are known to prey upon. Crows are also not any more dangerous in terms of spreading infectious disease than any other birds.

But in mass at this time of year, especially in the wee hours of the morning, they are obnoxiously loud. And their droppings underneath a roost tree can get to piling up pretty darn high and deep.

So what to do when you've had enough of crows?

Get into the Halloween spirit and try some scaring devices. But be prepared to have quite a repertoire in your bag of tricks. You're not dealing with any "bird brain" when it comes to crows.

The brain, as a matter of fact, is especially well developed in the corvidscrows, ravens, jays, and magpies-a family of birds always considered intelligent for their ability to adapt quickly to changing circumstances. Like many corvids, crows can distinguish a person holding a gun from one holding a walking stick. After brief experience, they even recognize a former hunter even when he or she is unarmed.

Given that, putting the old owl decoy up in the tree probably won't work well; in fact, crows might actually gather to mob it.

Try auditory scaring devices instead. But keep in mind that these work best when crows have not been using a roosting site for very long, and they're usually effective for less than a year. Also consider that the crows may simply move to a neighbor's property, so you may want to enlist your whole neighborhood in a team effort.

Auditory scare devices include pyrotechnics such as cracker shells, firecrackers, and propane cannons, and recorded warning calls. These generally require permits from area police departments or may be restricted by noise ordinances. Devices that play recorded warning calls can be set up to operate automatically. (Some of the calls advertised as warning calls may actually be distress calls, which may draw crows to your site!) Use mobile sound equipment so the location of the sound can be changed. Try to elevate pyrotechnics above the crows.

Use of auditory scare devices should begin at least 1½ hours before dark, when the first birds are coming in to roost; it should stop with darkness. Do not continue any longer because the crows will just become accustomed to the sounds. Play alarm calls only 10-15 seconds every minute when the birds are coming in. When most of the birds are perched, play the call continuously until dark. Early morning scaring also can be used in conjunction with evening scaring and should begin as soon as the first bird movement is detected in the roost, often just before daylight.

If you've got or know kids with energy to burn, put them to work near the crow roost trees with a low-tech method -- beating on tin sheets or barrels with baseball bats.

Scaring roosting crows often takes four to five nights (or more!) of continuous effort until the birds move to an acceptable area. Auditory scaring devices can provide effective short-term control, especially when they are used in combination.

If you're not inclined to add to the crow noise with these techniques, try spreading nylon netting to create a barrier in the roost trees. Or spray crows with water from a high-pressure hose or from a 360-degree sprinkler mounted in the roost tree. Or illuminate the tree with high wattage lights (or be the first in your neighborhood to put holiday lights out!) These intervention strategies must be continuous and concentrated to be effective.

At last resort, you can try to modify the structure of the night roost to discourage crows. Thin up to 50 percent of the branches of roost trees, or remove some trees from dense groves to reduce the availability of perch sites and open the trees to the weather.

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