Life can be full of difficult choices and hard decisions. Sometimes, it’s easy to get discouraged by the roadblocks that face us on our journey. But we need to stay motivated and never give up on our dreams, no matter how challenging they may seem. Working through life’s struggles can be a rewarding experience if you keep your head held high and believe in yourself. It might take effort, but with determination and perseverance, anything is possible!
Have you ever wonder why birds fly away for the winter and come back for the summer? Well, people have been curious about this for thousands of years. In recent years, scientists have started looking into why birds migrate like this. Flight Paths is a book written by Rebecca Heisman about all the research and findings done on these amazing creatures. Dr. Bill Cochran was one of these researchers; he tried to track birds across the Canadian border using radio-tagging techniques.
Flight Paths was written by Rebecca Heisman and published by Harper, which is a part of the HarperCollins Publishers. It has been given permission to be reprinted here.
How a Tiny Radio Transmitter Revealed A Bird’s Secret Migration Journey
The world is constantly changing and growing, which means new opportunities are opening up for us each and every day. Our lives have become filled with more possibilities, so it’s important that we take advantage of the chances that come our way. By taking risks and trying something new, we can learn something valuable, gain a new perspective or find a path to success. So, don’t be afraid to explore your options – you never know what great things could happen!
Swainson’s thrush looks like a small, brown American robin. Its back is gray-brown and has a pale, spotted chest with white markings around its eyes. These birds are shy, so they forage for food on the forest floor where it’s harder to see them. Birders recognize them by their soft, spiralling tunes that can be heard in forests of Canada and America during summertime. In winter, Swainson’s thrushes fly south to Mexico and some parts of South America, then come back north again when it’s time to breed.
On May 13, 1973, researchers found a Swainson’s thrush on its way from winter to summer. They weighed and measured it like normal, but then added something special: a super small radio transmitter weighing only 5 grains. To attach this micro transmitter, they had to carefully cut some feathers and then use an eyelash glue – yes, that’s the same stuff used with false eyelashes – to stick it gently against the bird’s back. The glue was chosen because it doesn’t hurt the bird’s skin and will wear off after a few weeks or months.
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When the thrush was set free, it moved its wings around a bit to get used to something extra that had been attached. After that, it went back to searching for food and resting in preparation for continuing its journey. The thing that was attached to it didn’t make up much of its body weight (only 3 percent) so it wouldn’t bother the bird too much as it did what it usually does during the day. That night at 8:40 when the sun started disappearing, the thrush flew off northwest.
Bill Cochran, who had invented a way to record bird calls with a tape recorder and a bicycle axle fifteen years before, was waiting in an old Chevy station wagon. He had an antenna sticking out of the roof. Charles Welling and Bill followed the thrush into the sky using the roads as it flew away. They did not know that they were being followed.
At night, the only thing that could be seen was the small patch of road lit up by their car headlights. However, they heard a wavering ‘beep…beep…beep’ sound above them coming from a thrush they were following while driving. They had to keep going on this journey for seven days and after 930 miles, eventually lost the signal in rural southern Manitoba on May 20th.
Cochran and Welling tracked the altitude, speed, and distance of a bird on its journey. They also kept a check on its heading which gradually changed with time in accordance to magnetic north. This showed that birds use an internal magnetic compass to know where they are going during migration. Bill Cochran is famous among ornithologists for this and it wasn’t birds that initially drew him into this field; it was the space race.
The Birth of Radio Telemetry
In October 1957, the Soviet Union sent something amazing into space – the first ever created artificial satellite! It was just a metal sphere that made beeping sounds and it only worked for three weeks. Everyone with a good enough radio could pick up its signals and scientists as well as amateur hobbyists followed it in its journey around Earth. Eventually, Its battery ran out and it burned up in the atmosphere during January of 1958.
The launch of the first Sputnik satellite in 1957 caused a big stir globally. This included University of Illinois radio astronomer George Swenson who wanted to use the signals from this and later satellites to understand more about our planet’s atmosphere. In 1960 he got approval for his own beacon, which was added to a US version of the Sputnik program called Discoverer. He needed help with the project and asked Bill Cochran – who hadn’t yet completed his engineering degree – for assistance. Bill ended up finishing his studies only in 1964.
In the late 1950s, Cochran worked at a television station in Illinois while also studying engineering and working with Richard Graber to create a system for recording bird calls in the nighttime. By 1960, Graber had obtained a radar unit and hired Cochran to help operate it. Someone recognized Cochran’s skill with making things using tiny transistors which eventually helped him get a job with Swenson. Transistors were explored in 1947 but it was their inventions that made space missions and tracking wild animals easier.
A radio transmitter is powered by an oscillator. Inside this oscillator is a tiny quartz crystal. When it’s given electricity, the crystal changes shape slightly over and over again and creates a small electric signal at a specific frequency. To make the signal stronger, it needs to be ‘amplified’, which is kind of like how a lever can turn a small motion into something bigger. In electrical circuits, an amplifier does this by making the weak signal stronger.
Back in World War II, amplifying a signal to send it from one place to another required a big bulky device with glass tubes and lots of power. This was difficult to maintain as the tubes needed replacement often. But then something happened – a smaller, more efficient material called ‘semiconductor’ (originally germanium, later silicon) took its place. It allowed electrons to be switched on or off and made those bulky devices obsolete! Today these materials are used all around us in our electric circuits; like millions of them inside this laptop I’m using to write this.
In the 1950s, the U.S. Navy wanted to understand more about radio telemetry and began some experiments with it. They used it to study a jet pilot’s body and how cold-water suits worked for sailors. These tests inspired scientists to use radio telemetry in wildlife research too. In 1957, researchers tracked a penguin’s egg temperature with this method while some other folks tested out tracking animals by surgically implanting transmitters into them! These devices had limited range of around 25 yards but they were the first ones ever used like this. The Office of Naval Research even funded these kinds of animal tracking experiments because they hoped this would help them create better navigation systems.
At the time, Cochran and Swenson didn’t know that they were building radio beacons for the first U.S. spy satellites. All they understood was that its purpose was kept secret. Despite the limited budget and weight limit, they managed to build a device named ‘Nora-Alice’, which launched in 1961. Meanwhile, Cochran was still working at the Illinois Natural History Survey and someone there proposed using radio transmitters to track a flying duck!
A researcher at the Illinois River research station sent a mallard duck to the Urbana satellite monitoring station. There, a small machine was put around the duck’s chest with a metal band. The poor duck was confused since it had been in captivity for a whole week, but it still sat calmly and quietly on the workbench as its signal started being tracked by the receiver. Every time the duck took a breath, the metal band would slightly move which changed its frequency and caused different sounds from the receiver.
Swenson and Cochran took note of the changes in a signal when they released a bird. They noticed that whenever the bird was breathing faster or moving its wings more quickly, the changes in the signal also sped up. This gave them some of the very first data on how birds behave while they are flying.
Tracking Wildlife with Telemetry
Bill Cochran loves to joke around with telemarketers. So, when he got a phone call from a number he didn’t recognize, he said something funny as a greeting.
“Animal shelter! We’re closed!”
“Uh.. This is Rebecca Heisman calling for Bill Cochran?”
“Who?”
“Is this Bill Cochran?”
“Yes, who are you?”
Once we figured out that the person I was talking to was really Bill Cochran, an expert in radio telemetry, and that I wasn’t a telemarketer like he had thought, he told me he was busy but asked me to give him a call back at the same time tomorrow.
We first spoke with Cochran in the spring of 2021, when he was nearly ninety years old. It had been almost fifty years since his journey to chase a thrush bird in 1973. He and Welling stayed in the truck during the day while they waited for the bird to land, because they didn’t want to take a chance at staying at a motel if the bird took off suddenly. While Welling drove, Cochran changed the antenna so that it looked like a submarine crewman using a periscope. The bottom of the antenna support was installed inside their car and he could move it up and down or turn it around.
At some point, me and my friend got sick with flu while we were in Minnesota. We couldn’t find a doctor who would see us so we had to wait until we felt better before carrying on our journey. Meanwhile, when we drove through one town, the cop pulled us over even though we weren’t speeding! My friend stayed with the cop to sort things out while I kept going to look for where the bird (we were tracking) was flying. After it landed, I drove back to pick up my friend that spent a night in jail.
Cochran said the bird was lucky enough to get a strong wind pushing it forwards as soon as it left Minnesota so that it moved quickly. We had to drive faster than normal down the empty roads of North Dakota to keep up, but eventually the bird got too far away and flew into Canada before we caught up with it.
At first, they couldn’t get into Manitoba legally. So, they tried to listen at the border to an unknown signal fading away. The next day, they located a border crossing with a giant antenna on top of their truck. While there, their car started breaking down and needed repairs. Charles then hopped onto the hood of the truck and poured some gasoline into the carburetor to keep it going. When they found ditches with rainwater nearby, they used that to fill up their radiator. Eventually, they were able to make it into town for repairs.
Cochran hired a local pilot to take him up in an airplane and find the bird that had been marked with a radio-tracker. But, unfortunately, their search failed. The information from their journey was made into a small three-page paper but it didn’t tell the story of all their adventures.
In 1973, a man named Cochran went on a journey to follow a bird with a radio-tag. Because of his success in this, he soon became very popular among all the wildlife biologists around him. First, he worked with Rexford Lord from the Illinois Natural History Survey, who wanted an accurate way to count cottontail rabbits. Companies like Honeywell had tried to build radio tracking systems for animals but failed; that’s when Cochran decided to use smaller and simpler components than others before him. He put these parts together and sealed them with plastic resin so they wouldn’t get wet or damaged. Even today, it takes balance and trade-offs when fitting an animal with a radio transmitter – such as making sure the battery is big enough for long life and antennas are not too heavy or long – but code may have been the first one to really figure out how to do it properly!
Cochran and Lord created special transmitters that cost only 8 dollars each, weighed a fraction of an ounce each and worked from up to two miles away. They put the transmitters on animals like skunks, raccoons, and rabbits so they could track their movements. People were amazed when Lord talked about their research at a conference in 1961, giving Cochran lots of job offers. He chose not to patent his inventions which let other biologists copy them and even stay in his house for help with telemetry. When asked why he chose wildlife over satellites, Cochran said he didn’t want to get paid a lot to build weapons that hurt people.
