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Peregrine Falcons Flock to US Cities - 2002-05-15


Nearly three years ago, the U.S. government removed the American peregrine falcon from its endangered species list, but scientists continue monitoring the birds closely to be sure the species continues its recovery. That work can take researchers to areas not usually associated with wildlife, like a hotel balcony in the middle of a city.

Mary Hennen is an ornithologist at the Field Museum of Natural History in Chicago, and is head of the Chicago Peregrine Program. Today, she has to snatch two peregrine falcon chicks from their nest on the 25th floor balcony of an executive hotel in downtown Chicago. First, she straps on a bicycle helmet for protection. Some birds are very protective of their young.

"It varies a little, depending on the parents I have," she says. "Some are more aggressive than others. This is a fairly aggressive pair. The fairly typical behavior is to swoop at you. That is for intimidation and you want to duck away."

Peregrine falcons have historically lived along mountain ranges, river valleys or coastlines. They were driven to near extinction in the United States 30 years ago by the use of the chemical pesticide DDT. Smaller birds ate insects and seeds contaminated by the pesticide, the falcons ate the smaller birds and that caused the peregrines to lay abnormally thin-shelled eggs that often broke before hatching. By 1970, there were no peregrine falcons east of the Mississippi River, and they had nearly disappeared from the West.

Thanks to a banning of DDT and a federal peregrine restoration project, the birds have been making a steady comeback. More than 6,000 peregrine falcons have been released into the wild since the mid-1970s, and Mary Hennen says many have flocked to cities.

"They are naturally cliff-dwelling birds, and the city is nothing but a pseudo-cliff," she explains. "There are lots of ledges and ample prey among the bird species we have: lots of pigeons, starlings, plus the birds that migrate through."

Scientists track the birds by placing bands on their legs when they are young. Two peregrine chicks were born in late April on the balcony of Lois Ebensberger, a Texas woman who is living at this hotel while working on a project in Chicago.

"[I was] working at my desk one morning and as I turned to get up, I noticed a huge bird in my flowerpot," she says. "Ever since then I just started observing them, watching them, talking to them."

Mary Hennen and an assistant dash in from the balcony carrying the two unhappy peregrine chicks and their mother. A veterinarian from the Lincoln Park Zoo in Chicago draws a small amount of blood from their wings, and Mary puts two bands on each chick's leg.

"By being able to take the blood samples, to do genetics [testing], to look at inbreeding, and to band the young, we are able to track them and be able to know that we have birds from Minnesota down in Illinois breeding, or the fact that we have a birds that are 14 years old and still breeding, that is how we are able to assess the population: are they successfully recovering? Are these young surviving once they are out of the nest?" she asks.

Statistics suggest many young peregrines are surviving once they leave the nest. Their population has grown from a low of a few hundred in the 1970s to an estimated 3,500 birds today. Ms. Hennen says these two chicks will leave their parents by the end of June.

"Once they take off from the nest, they spend about three weeks learning how to fly," she explains. "The first flight is usually a glide down to another level."

Illinois has at least nine breeding pairs of peregrine falcons, most of them living in the Chicago area.

Animal researcher Matt Gies says playing a role in the birds' recovery is worth a few bites and scratches. "I have been hit in the head and in the face and on the back of the neck," he recalls. "It can hurt but it is rewarding."

While the peregrine falcon is off the federal endangered species list, it is still on the state of Illinois' list. Scientists are hoping a few more successful hatchings like this one in Chicago could change that within a few years.

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