CHRISTINA LARSON, AP Science Editor
TAKOMA PARK, Md. (AP) – A plump robin wearing a small metal backpack with an antenna hops around a suburban yard in Takoma Park, then plucks a cicada off the ground for a snack.
Environmentalist Emily Williams looks through binoculars from behind a bush. On this clear spring day, she delves into her love life. “Now I’m looking to see if he’s found a mate,” she said, scrutinizing his interactions with another robin in a nearby tree.
Once the bird moves at the end of the season, it will rely on the backpack to transmit frequent location data to the Argos satellite, and then back to Williams’ laptop, to track it.
The goal is to understand why some American robins migrate long distances, but not others. With more precise information on nesting success and conditions in breeding and wintering areas, “we should be able to determine the relative roles of genetics in relation to the environment in determining why birds migrate. said Williams, who is based at Georgetown University.
Putting tags on birds is nothing new. But a new antenna on the International Space Station and receivers on the Argos satellite, along with smaller tracking chips and batteries, allow scientists to remotely monitor songbird movements in much more detail than ever before.
“We’re in a sort of golden age for bird research,” said Adriaan Dokter, an environmentalist at Cornell University who is not directly involved in the Williams study. “It’s pretty amazing that we can follow a robin with smaller and smaller chips by satellite. Ten years ago, it was unthinkable.
The device this robin is wearing can give precise locations, at around 30 feet (around 10 meters), instead of around 125 miles (200 kilometers) for previous generations of beacons.
This means Williams can tell not only if the bird is still in town, but on which street or backyard. Or that he flies away from the suburbs of Washington, DC to land on the lawn of the White House.
A second new beacon, reserved for the heaviest robins, includes an accelerometer to provide information on the movements of the bird; future versions will also be able to measure humidity and barometric pressure. These Icarus beacons work with a new antenna from the International Space Station.
This antenna was first turned on about two years ago, “but there were some problems with the power supply and the computer, so we had to bring it down with a Russian rocket and then transport it from Moscow. in Germany to fix it, “said Martin Wikelski, director of the Max Planck Institute of Animal Behavior, whose science team is perfecting the technology. After” the usual troubleshooting for space science, “the antenna was turned back on this spring. .
As researchers deploy precision beacons, Wikelski envisions the development of an “Internet of Animals” – a collection of sensors around the world giving us a better picture of the movement of life on the planet. “
The American Robin is an iconic songbird in North America, its brilliant chirping is a harbinger of spring. However, its migratory habits remain a little mysterious for scientists.
“It’s amazing how little we know about some of the more common songbirds,” said Ken Rosenberg, conservation scientist at Cornell University. “We have a general idea of migration, a map of the range, but it’s really just a general impression. “
An earlier study that Williams worked on showed that some robins are long-distance migrants – flying over 2,780 miles (4,480 km) between their breeding grounds in Alaska and the winter grounds in Texas – while others hopping around in a single backyard most of the year.
What factors cause some robins to migrate while others do not? Does it have to do with the food available, temperature fluctuations or the success of mating and rearing chicks?
Williams is hoping that more detailed data from satellite beacons, combined with records of nesting successes, will provide information, and she is working with partners who tag robins in Alaska, Indiana and Florida for a study of three. years.
Scientists have already installed GPS tracking devices on larger raptors, but the technology has only recently become small and light enough for some songbirds. The tracking devices must be less than 5% of the weight of the animal so as not to encumber them.
In a yard in Silver Spring, Md., Williams deployed nylon netting between tall aluminum poles. When a robin flies into the net, it delicately untangles the bird. Next, she holds it in a “bander hold” – with her index and middle fingers on either side of the bird’s neck, and two more fingers around its body.
On a tarp, she measures the length of the robin’s beak, cuts a fingernail, and plucks a feather from the tail to assess its general health.
Then she weighs the bird in a small cup on a scale. This weighs about 80 grams, just above the threshold to carry the Argos satellite tag the size of a penny.
Williams makes a makeshift saddle with a sheer jewelry cord wrapped around each of the bird’s legs. She then tightens the cord so that the tag rests firmly on the bird’s back.
When she opens her hand, the robin jumps to the ground, then takes a few steps under a pink azalea shrub before flying away.
In addition to providing very precise locations, the satellite beacons transmit data that can be downloaded remotely to Williams’ laptop. Data from the old tags could not be recovered unless the same bird was recaptured the following year – a difficult and uncertain task.
Wilkeski hopes the new technology will help scientists better understand the threats birds and other creatures face from habitat loss, pollution and climate change.
“It’s detective work trying to figure out why a population is in decline,” said Ben Freeman, a biologist at the University of British Columbia’s Biodiversity Research Center. Better information on migration corridors “will help us look in the right places”.
A 2019 study co-authored by Cornell’s Rosenberg showed that North America’s wild bird population has declined by almost 30%, or 3 billion, since 1970.
He said tracking birds will help explain why, “At what point in their annual cycles do migrating birds face the greatest threats? Is it the exposure to pesticides in Mexico, the clearing of rainforests in Brazil, or is it what people are doing in their backyards here in the United States? “
Follow Christina Larson on Twitter: @larsonchristina
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