Space Odyssey A New Technology for Following Songbirds
There are 1.6 billion songbirds in Europe and half of them fly south for the winter. Scientists would like to follow them -- but keeping up isn't easy. At least for now.
Martin Wikelski is late arriving at the Radolfzell air strip on Lake Constance because of a lynx. The feline lives in the Swabia Jura mountain range in southern Germany and wears a radio collar, but for the last 11 days, the radio receiver has been silent. Forest service workers turned to Wikelski for help.
As head of the Max Planck Institute for Ornithology in Radolfzell, Wikelski doesn't just have an airplane and over 1,000 hours of flying experience: His Cessna 172 is equipped with technology for tracking animals that have been tagged with radio transmitters.
In his tight cockpit, the researcher balances the radio receiver on his knees. Antennas are mounted beneath the aircraft's wings. Wikelski normally focuses his activities on migratory birds and bats, but every now and then he offers his services to the search for a missing wild cat. Once the mission is completed, he turns to his real task for tonight: For once, he's not searching for animals, but imitating one -- specifically, a common blackbird.
He quickly affixes a battery-powered radio transmitter under the plane's left wing and takes off again. On the ground, his coworkers sit in two VW buses and listen to the signals sent from above.
The vehicles are equipped with impressive antennas that can be telescoped upwards to a height of up to six meters (20 feet). But after just a few minutes, Wikelski's coworker Jesko Partecke sends him a text message: "We've lost you." The researcher frowns in frustration.
The flight was supposed to be something of a dress rehearsal for the technology ahead of possible deployment just a few hours later. Wikelski's team has tagged 24 female blackbirds with radio transmitters in Bodanrück, a forested area on the scenic west shore of Lake Constance. Each of the transmitters weighs just two grams and they are supposed to help track the animals as they fly south. Because the transmitters are also able to measure air pressure, the researchers will be able to measure the birds' altitude in addition to their route, an added bit of data that has never before been collected.
Some 1.6 billion songbirds live in Europe and half of them fly south for the winter. The journey "takes place over the course of perhaps 10 nights in the fall," says Wikelski. "There's a lot going on in the air. It's as full as the highway to northern Italy on Easter weekend." About a third of the blackbird population in Bodanrück makes the trip, with females migrating in greater numbers than males.
On cloudless nights, the animals memorize the sky above their starting point before heading off. Sometimes they leave at dusk, sometimes after midnight. "Once the animals have determined their direction of flight, they try to fly as straight as possible," Partecke explains. The birds then fly either across Lake Constance and Switzerland or toward the Black Forest and then onward to France. Depending on wind speeds and direction, the animals travel between 30 and 40 kilometers (19 and 25 miles) per hour.
Because researchers have previously marked blackbirds with rings, they know that most of them fly to an area at the base of the Pyrenees Mountains and winter there. Some birds, though, carry on to Spain or the Balearic Islands.
But some important questions have yet to be answered. How, for example, does a blackbird decide to migrate? How do they decide to suddenly switch from daytime to nocturnal activity and why do they decide they'll take on the rigors of the journey, even if it means a weakened immune system?
"We want to know to what extent genetics and environmental conditions influence whether a bird migrates or not," says Partecke. In their search for answers, the research team also draws blood samples from the birds they tag for genetic analysis.
One thing seems certain: The first blackbirds of the year could start their migration this evening. The researchers want to chase them in their vehicles. "It's a kind of scavenger hunt," Partecke says. "But you have to stay relatively close to the birds so as not to lose them." And that means that the transmitters attached to the birds have to work, but given the equipment test with Wikelski's airplane, there is cause for doubt.
Researchers believe that blackbirds migrate individually, but because of the astounding paucity of data, they aren't even sure about that. Larger birds like albatrosses or geese can easily be outfitted with GPS transmitters. But blackbirds, which only weigh around 100 grams, aren't able to carry heavy technical equipment. That is why Wikelski's team is using lighter radio transmitters -- and, if they can get their equipment to work, chasing them with cars.
Next year, or perhaps the year after next at the latest, this kind of research should become far easier. For the last 15 years, Wikelski has been part of an international project called "Icarus," which hopes to outfit blackbirds and many other species around the world with solar-powered transmitters. The signals they send are then to be collected by extremely sensitive receivers mounted on the International Space Station. In addition to the animals' location, the data could include information about acceleration and body temperature.
Wikelski and the others working on the project envision nothing less than a global network of living sensors -- an Internet of animals, if you will. They hope to observe the migratory patterns of birds, fish and mammals and they anticipate that such data will enable them to predict storms and climatic shifts -- and perhaps even volcanic eruptions, earthquakes and tsunamis. From the vantage point of space, they hope to be able to track the outbreak of diseases like bird flu, prevent tropical-wood smuggling and improve the protection of endangered species such as the rhinoceros.
Of course, keeping tabs on wildlife from space is nothing new. The satellite monitoring system Argos has been around since the late 1970s. But its frequencies are full, to the point that it can hardly be used anymore in Europe -- a problem that Icarus should be able to avoid. Plus, it foresees tagging many more, and much smaller, animals than Argos with the mini-transmitters.
Next summer, a Soyuz spacecraft is scheduled to launch the special antenna -- constructed by the German company SpaceTech -- into space where it will be affixed to a Russian module of the International Space Station. From an altitude of around 400 kilometers, it will observe a relatively small area of the earth's surface at any given time, making it possible to pick up the weak signal.
With a signal strength of just five milliwatts -- wireless Internet routers are 20 times as powerful -- the transmitters will broadcast on a frequency of 401 megahertz, which has been reserved around the world for the tagged animals. Because they are solar powered, scientists hope the transmitters will broadcast for several years, allowing them to document entire animal lifespans.
If the animals can be recaptured -- and Wikelski believes it won't be too difficult when it comes to blackbirds -- the transmitters could theoretically be removed. That won't, of course, be possible in all cases, but scientists say that the technology's extremely light weight will ensure that the animals hardly notice it.
Observing migratory birds from orbit is one thing, but Wikelski and his team hope the system will be able to do much more than that -- and that might be Icarus' Achilles heel. The potential overly high hopes for the system might lead to disappointment.
Wikelski's Career Depends on Icarus
Icarus' hope of predicting natural catastrophes seems illusory at first glance. Wikelski, though, excitedly points out that elephants in Indonesia moved to safe ground ahead of the 2004 tsunami and that the movement patterns of goats on Mt. Etna in Sicily foretell eruptions. "Since ancient times, we have indications that something like this is possible. Even if such a forecast works only in a fraction of instances, it would be huge."
The scientists point out that people trust dogs to help find avalanche victims in the mountains and drugs at airports. "But when it comes to wild animals, we have our doubts because we don't understand them." Icarus will change that, he hopes. "Some things will prove to be untrue, but others could be very valuable," Wikelski says confidently.
The ornithologist is well aware that he is taking a risk with the project; his reputation as a scientist is at stake if nothing comes of it. But if Icarus really does live up to its promise, then in the future, scientists sitting at their home computers will be able to see the world through animals' eyes.
For the ornithologists currently trying to track blackbirds on the shores of Lake Constance, however, things aren't quite so luxurious. They have to use their vehicle-mounted antennas to monitor the birds so as not to miss the moment when they take off. And they have to hope that the transmitters work despite the disappointing test with the airplane.
After Wikelski lands, he and his team set up their technology in preparation for nightfall. They are parked at the edge of a cornfield high above the village of Stahringen, around three or four kilometers from the trees where the blackbirds nest. Gradually, the clear night sky begins glittering with stars.
It is a perfect night for flying. But an hour goes by, and then another, without any of the tagged birds taking off on their journey south. The scientists need to be patient. And they need warm clothing. The thermometer in the VW bus shows 8 degrees Celsius (46 degrees Fahrenheit), but because of an icy wind, it doesn't even feel that warm.
High tones regularly peep out of the receiver speakers, incomprehensible for the uninitiated. Wikelski, Partecke and the rest of the team interpret the volume of such signals as an indication that none of the tagged birds has yet set off. At some point, the frozen team packs up their equipment and heads home.
The next morning, they realize they should have stayed just a bit longer. At exactly three minutes past midnight, their automatic data collection station recorded the first of the blackbirds departing Bodanrück for its winter quarters.
On the next clear autumn night, though, the scientists will be back, hoping to start the chase.