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High structures disrupt migration, endanger birds

In all the years of books and television coverage dealing with Egyptian culture I've never run across a segment that tells of birds colliding with the great pyramids. But I suspect it probably happened. Since humans have been erecting structures there have likely been consequences for the birds. Unintended, to be sure, but very real.

Unintended consequences are an almost inevitable part of life. We dream up a great idea, create a plan, execute the plan and evaluate it. In the end, there are usually effects stemming from our original idea that were totally unexpected. Take the introduction many years ago of rabbits for sport to the continent of Australia. Great idea, lousy result. Rabbits, for decades, have been a major pest problem in that country. Years ago Congress levied a very high tax on luxury goods thinking the well-to-do weren't paying enough. As a result, sales of such goods as yachts went into a severe slump leaving thousands of hourly workers jobless. Sometimes the actions can have positive effects, such as the thousands of reefs created in the Pacific Ocean from the sinking of ships during World War II.

Certainly the builders of structures don't intend to go out and disrupt migration and kill birds, but it is one of the byproducts of our modern society. Power lines, towers, buildings, and even automobiles all create a hazard for flying birds. For example, on one night in 1998 in western Kansas, 10,000 Lapland Longspurs died in collisions with a single television tower and its attendant guy wires. While this occurrence is rare, lesser kills have been documented virtually everywhere and are usually associated with bad weather. In total, biologists estimate aerial collisions may account for as many as 100 million bird deaths each year.

Of all the human caused bird deaths, it is thought that glass is the number one culprit. Skyscrapers in cities large and small are often covered in plate glass that is invisible to birds. Collisions are a regular occurrence. Number two? House cats. We've mentioned this one before. Third on the list are automobiles. Most highways are scattered with the remains of road-killed birds. Structures such as towers, and smokestacks also represent a significant threat.

The exponential increase in wind energy and its associated towers will increase the hazard to bird migration in certain areas. How much is a subject of debate. Studies have been done in California and Minnesota and have found little impact. The move to tubular towers with no guy wires (such as DMI's product) is thought to be the reason for the low effects.

Overhead power lines have long been associated with electrocutions and bird strikes. Power companies have taken great pains to mitigate the effects since a significant percentage of outages can be attributed to birds. James Holnly, System Maintenance Supervisor for Cass County Electric Cooperative said as many as 400 man-hours and $5,000 per year are directed toward minimizing the companies impact on bird movements and electrocutions. While they are trying to make their lines more visible to birds, especially near WPAs (waterfowl production areas), the company's effort is "around transformers and other junction areas where most problems occur," said Holnly.

Ultimately, we will never eliminate bird strikes on manmade structures. Studies and efforts to mitigate the effects continue. Burying power lines, different colored lighting, careful tower location, and less transparent glass are just a handful of solutions. But with structures continuing to be built (70,000 applications for wireless and mass media facilities reach the FCC every year), the problem will not go away. Call it the cost of doing business and an unintended consequence of living in the modern world.