Urban Invasion Wily Foxes Embrace Easy City Life
More and more foxes are seeking their fortunes in German towns, where food is ample and people sometimes mistake them for overgrown dachshunds. But the furry predators come bearing an unwelcome guest -- parasites.
Fox sightings used to be rural affairs, limited to flashes of reddish-yellow eyes reflected in the headlights of passing cars.
But these days, it is not unusual to see foxes walking around the center of major German cities. In Munich, they've even been seen crossing the street along with the pedestrians. Foxes have become so accustomed to people that some can be hand-fed like dogs. The cunning canine predators have realized that cities provide them with more food and shelter than the surrounding countryside.
That concerns Andreas König, a professor of wildlife biology and wildlife management at the Technical University of Munich who has studied these city foxes for several years. While rabies has been largely wiped out by medicated traps, foxes breed another danger for humans: small fox tapeworm. The parasite can cause a potentially fatal infection called echinococcosis.
Foxes pick up the tapeworm from mice, one of their favorite field delicacies. Tapeworm eggs end up in fox feces, which are spread around gardens and cities by rodents and slugs. Humans, in turn, contract the tapeworm by unwittingly eating its eggs -- from unwashed hands after yard work, from seemingly benign sidewalk litter, or while munching on unwashed garden vegetables. Dogs and cats can also bring the worms indoors after playing outside.
Once inside a human host, the parasite is patient. It can take between 10 and 15 years from the initial infection for symptoms to appear. The first signs of echinococcosis resemble jaundice, as the worm's larvae ravage the victim's liver. Untreated, the infestation can spread to other internal organs. It can only be slowed by chemotherapy. There is no permanent cure.
With foxes living so close to people -- sleeping under their backyard sheds by day, feasting on their compost piles by night -- König has seen an alarming rise in the number of cases of tapeworm among Munich residents. Germany had 16 cases in 2006, and König says the risk of contracting echinococcosis today is seven times greater than it was 20 years ago.
Ten Times More Food
And it will likely get worse. Food sources for foxes are 10 times more plentiful in the city than in the country, so they are multiplying rapidly in urban areas -- Germany's red fox population has quadrupled in the last 15 years. People help them thrive by leaving cat food at their backdoors and compost piles unprotected.
Some residents are intentionally feeding the foxes, even by hand. As a result the foxes are "losing their shyness," König said. They have become so domesticated that people sometimes mistake them for dachshunds. And the foxes are enjoying the attention. "The next generation (of foxes) will get closer, you may be able to touch them," König said. "Then the generation after that will come into your house."
One particular fox couple in the village of Grünwald south of Munich ("Felix" and his girlfriend "Speedy") waits for the proper signal to cross the street along with the pedestrians, he said. On one occasion König observed them at rush hour crossing a busy thoroughfare along with the work crowd. "No one noticed them," König says.
With rabies largely eradicated here through immunization treatments, König worries that people have a false sense of security about foxes. Unlike rabies, there is no way to immunize foxes against tapeworm. "We tell people that on the one hand, you don't have to be afraid because the fox is a lovely animal," said König. "But on the other hand, the fox is a wild animal."
Foxes and Their Wily Ways
With the help of Ph.D. student Christof Janko, König has been tracking the habits of foxes in Munich and its suburbs. He said the best places to find them are at schools, building sites and old-age homes, where foxes can find plenty of discarded leftovers.
Every six months or so, they trap a handful of foxes and tag them with radio frequency identification (or RFID) chips that allow the scientists to follow their movements.
Most nights, Janko can be found sitting in a parked car in the Munich suburb of Herrsching. Holding a simple antenna device out the window with his left hand and a receiver in his right, Janko listens for the tell-tale beeping to get louder, signaling that his fox is close by.
He is currently following six foxes, to which he has assigned names and radio frequencies. When the signal is the strongest, he pulls out a compass and maps the coordinates of the spot in his notebook. Over time, he develops a complete picture of the fox's behavior: where they sleep, where they play and, most important of all, where they find food.
"Every fox is special," he said.
Ronda, for one, likes to roam backyard gardens, and is so docile she can be hand-fed meat. Naomi ventures down into the center of the village, often lounging on the grass next to the train station when not looking for food. Ole, a male, likes to stay up north of the village.
'The Fox Man'
On this crisp September night, under a star-studded sky and a wedge-shaped moon, Janko is looking for Swift, a female fox often spotted in a quiet residential part of Herrsching, a town of 10,000 35 kilometers southwest of Munich. Janko thinks she may be in a nearby meadow hunting mice.
Under a street lamp at the corner of Leitenhöhe and Adolf-Ochert-Weg, he scrolls through the channels on his receiver to the frequency he has assigned for Swift, then raises the antenna above his head. He slowly turns around, and listens for the beeping to grow louder. When he finds the loudest point, he pulls out his compass and writes down the coordinates.
He walks further down the street and does the same thing. With these two coordinates in hand, he is able to pinpoint Swift's location on a satellite image of the neighbourhood. "You have to move fast between points because the fox is moving, too," he says.
Janko has studied groups of foxes in Herrsching for two years as part of three-year scholarship at the University of Stuttgart. He sometimes spends as many as six nights a week scanning the airwaves for them. His girlfriend has learned to be patient. By now, many people in town recognize him, and affectionately call him "The Fox Man."
The foxes also recognize him, by his scent. A few will walk coolly up to him, give him a few sniffs, and then keep going. Others run and hide. So far, of the 19 foxes he has followed over the two years, he has lost one to a car and three to hunters.
Those who don't know who he is wonder what he is doing lurking in the shadows, holding a four-pronged contraption above his head. Some think he is casing their houses, planning a break-in. Others think he is a policeman looking to trap speeders. But a big part of his job is educating residents about the foxes among them, and how they can avoid the dreaded tapeworm. He plants medicated bait in their gardens for the foxes that will rid them of the parasite. The problem is that the fox can immediately pick up another tapeworm by eating another infected mouse.
Janko worries that when his studies are done next year, community members won't have anyone to educate them about the foxes living among them. And the fox population is only going to multiply here.
Munich has an average of between eight and 10 foxes per square kilometer (compared with between three and five in the countryside), making a total population of between 2,000 and 3,000 in the city. The German capital Berlin probably has between 7,000 and 9,000 urban foxes.
While the actual infection rate among foxes in Munich and its suburbs is lower than in the countryside -- between 10 and 20 percent in the city compared with 80 percent in rural areas -- König said people are more at risk of getting the tapeworm in Munich and its suburbs because people and foxes live closer to each other.
A survey of Grünwald residents shows that more than 90 percent think the foxes have a right to live in peace. However, they also want to rid the foxes of tapeworm, so König has his work cut out for him.
The key, he says, is to "destroy the circle between the mouse and the fox." Using medicated bait, the foxes can be periodically de-wormed. Without worm-infested fox feces, mice have no way to pick up the infestation; clean mice can't spread the tapeworm to more foxes. The tapeworm's cycle of life is broken. That, König says, "is good for us."
© SPIEGEL ONLINE 2007
All Rights Reserved
Reproduction only allowed with the permission of SPIEGELnet GmbH