Wildlife populations around the world are in crisis. Recent analysis by the World Wide Fund For Nature estimated that over the past 50 years, wildlife populations have reduced by 73 per cent.
In the face of these unprecedented declines, it’s more important than ever that scientists understand the challenges animals face and how they’re responding to a changing planet. This requires data collection on a scale never attempted before – tracking the lives of animals at a global level – and scientists are turning to technology to make this mammoth task possible.
The development of radio-tracking technology has already opened many new research avenues for scientists interested in animal behaviour, but these studies have been limited by the large size of the tracking devices and the need to follow the animals with receivers, or retrieve the tags later, to access the data.
In industry, new technological advances such as miniaturised sensors and communication devices have enabled the development of large-scale wireless digital networks that track the location and status of objects, from shipping containers to factory equipment – known as the ‘Internet of Things’ or IoT.
ICARUS – the International Cooperation for Animal Research Using Space – aims to leverage this technology to create a global animal observation network to track and monitor wildlife on an unparalleled scale.
The system uses state-of-the-art miniature transmitters to relay data about animals’ movements, activity and even health, to receiver antennae in space, allowing scientists to tap into a wealth of research data through their computers.
“We’re about to have an internet of animals and that’s super exciting,” says Prof Martin Wikelski, Director of the Department of Migration at the Max Planck Institute of Animal Behavior and ICARUS Initiative founder.
ICARUS data is being used to answer long-standing scientific questions about animal navigation, learning, culture and communication, and to assist in real-time conservation decision-making.
They also hope to apply the animal tracking data to real-world problems, by tapping into the ‘sixth sense’ of animals to develop early warning systems for wildlife disease outbreaks, and even earthquakes and other natural disasters.
“We can now think differently and do experiments on a global scale that we never did before,” Wikelski says.
The first ICARUS tags, which went into production in 2017, weighed around 4g (a fraction of an ounce) and transmitted a GPS location and whether the animal was alive or dead, along with environmental data such as temperature and humidity.
Since then, the tags have been improved, making them even smaller, adding new sensing capabilities and integrating new technology such as on-board artificial intelligence to streamline data processing. It’s also made them cheaper; now, the tags cost around €50–100 each (about £40–85), making large-scale tagging more affordable.
The team is currently working on the next generation of tags, which will weigh about 1g and be able to relay detailed information about the animals’ movements within their habitat.
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Blackbird migration
The first animals to be equipped with ICARUS tags were blackbirds, as part of a research project to understand songbird migration. Researchers have now tagged nearly 700 blackbirds across Europe, from Finland to Spain, and are tracking their movements at the continent-wide level.
To be able to “follow individual animals of different populations continent-wide, that’s a very exciting and extremely positive adventure,” says Dr Jesko Partecke, also of the Max Planck Institute of Animal Behavior.
This project is already providing new insights into blackbird behaviour in Europe. For example, across their European range, blackbirds have different wintering strategies depending on where they live.
Those living in northern Europe migrate south to winter in Spain and southern France, where they join resident blackbirds that stay in these warmer climates year-round.
Data from 118 tagged blackbirds, received by antennas mounted on the ground and on aircraft, showed that they prepare for long-distance migration by decreasing their heart rate and body temperature for around a month prior to their departure.
This strategy means that migrating blackbirds have a similar energy expenditure to resident blackbirds, despite the huge energy requirements of long-distance flight.
The ICARUS tags are available in a variety of designs, including ear tags for mammals like rhinos, cheetahs and giraffes; leg bands for birds; and backpack-style tags for bats and large insects.
The latter allowed researchers to perform the longest continuous tracking of migrating insects. They attached tags to 14 migrating death’s-head hawkmoths and used antennae mounted on light aircraft to track their flight for 80km (approx 50 miles) on their way towards their winter breeding grounds in the Mediterranean.
They found that the insects can maintain straight flight paths over long distances – even in high winds, offering scientists a window into the species’s sophisticated internal compass.
Setting up a global network
Since its inception in 2012, the ICARUS project has experienced several setbacks, from technical and logistical to geopolitical.
The ICARUS antenna was installed on the International Space Station (ISS) in August 2018, and testing of the system was due to begin the following summer. A defect in the power supply on board the ISS delayed this step, however, and the ICARUS observation system wasn’t switched on until March 2020.
The first research projects using the system began in September of that year, with ICARUS tags deployed on 15 species worldwide.
Then, after Russia invaded Ukraine in February 2022, the ICARUS collaboration paused operations. Fortuitously, the team had already started developing a satellite-based receiver system that will eventually take over from the ISS antenna.
CubeSats are tiny satellites made up of custom-built 10cm (4in) cubes that perform a variety of experiments in orbit. ICARUS is currently preparing to launch its first CubeSat in the autumn of 2025. This will allow it to send and receive data from ICARUS tags around the globe.
This is just the beginning, though – the team hopes to add more CubeSats to its arsenal, ultimately forming a constellation of satellites that can collect near real-time data around the globe.
In the meantime, the researchers have been making use of a network of ground-based antennas to communicate with ICARUS tags that have already been deployed. This system allows Partecke to track the movements of songbirds across Europe.
“We get instant messages from our blackbirds sent to our computers, and we know what they’re doing [and] how they’re doing on a European scale,” he says. “For us, it’s just spectacular.”
Tracking songbirds at the continental level is already offering answers to long-standing questions about their behaviour, life history and conservation, but with the launch of the ICARUS CubeSat next year, Partecke hopes to answer even bigger questions about bird migration. “We have to become global,” he says.
The ICARUS team wants the data collected by its tags to be available to scientists, conservation managers, park rangers and citizen scientists everywhere.
Data from tagged animals across the globe is recorded in a freely accessible database called Movebank, which Wikelski describes as a “permanent digital museum” of animal data.
Movebank now contains data on the movements and behaviour of over 260,000 animals from more than 1,400 species. Each tagged animal is given a unique identifier in Movebank, standardising the way that animal data is stored and simplifying the process of data analysis.
Filling the knowledge gaps
In 2021, the team launched MoveApps – a free platform of analytical tools to help scientists make sense of all that data. The system allows programmers to develop data-analysis tools that scientists can apply to the animal-tracking data stored in the Movebank database.
“We want to democratise information gain, so that a farmer in Niger or a fisherman in the Galapagos can have the same information that a scientist has in Europe,” says Wikelski.
This data could help researchers address major scientific and conservation knowledge gaps, from how animals orchestrate their mass migrations, to what is driving population declines. This detailed understanding of how animals sense and interact with the environment will also foster a deeper connection to the natural world, Wikelski says. “Emotional connectivity allows conservation.”
Tracking turtles in the open ocean is one way it’s being used to do this. An enduring mystery in conservation biology is what happens to sea turtles in the period between emerging as tiny hatchlings on beaches around the world, to returning to coastal waters as dinner-plate-sized juveniles.
These so-called ‘lost years’ that young sea turtles spend in the open ocean have proved extremely difficult for researchers to study.
“Those early life stages are the foundation of the rest of their lives,” says Dr Kate Mansfield, a professor of conservation biology at the University of Central Florida, who is collaborating with ICARUS on a project that will track the movements of sea turtles in the open ocean.
“If you’re working with protected species or animals that are of conservation concern, you really want to know everything you can about them at every single life stage,” Mansfield says. Currently, “that early dispersal stage that’s associated with the sea turtles’ lost years is really the biggest data gap”, in sea turtle biology, she explains.
In recent years, satellite tracking technology has allowed Mansfield to begin studying this vital life stage in more detail. The initial tracking studies have already revealed that young sea turtles don’t just passively drift on ocean currents – as was long assumed – but sometimes they actively swim. This data is proving vital in helping conservationists seek legal protection for critical sea turtle habitats.
But this research is still limited by technical challenges. For example, currently available tags are still too large and heavy to be attached to hatchlings.
“When you’re satellite tagging an animal, you want to have a tag that’s not going to bother them, and you want a tag that’s as small as possible, that doesn’t alter their behaviour or cause the animals to spend more energy moving through their environment,” Mansfield says.
In addition, most available tags don’t provide reliable and precise global-poistioning system (GPS) locations, or fine-grained information about the turtles’ movements within their habitat – data that could be game-changing for researchers like Mansfield.
The conservation community needs “smaller tags, more reliable tags, [and] tags that have sensors that allow us to really get at the finer-scale movements of what these animals are doing,” she says.
ICARUS’s next generation of small, lightweight and sensor-rich satellite tags promises to address these challenges, revealing more details about the lost years of sea turtles.
Monitoring the Earth through animals
But the potential applications of ICARUS don’t end there. Animals sense and respond to the environment around them, so the ‘internet of animals’ could offer new insights into non-living components of the natural world.
“Animals give us unbiased information about the environment,” says Wikelski, which can be leveraged alongside more traditional Earth-monitoring systems, such as satellite imagery.
For example, the ICARUS team hopes to use wildlife movement data to predict earthquakes. Folk tales have long told of animals acting strangely in the hours before an earthquake hits, whereas current technology gives us just a few seconds or minutes warning of impending disaster.
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Wikelski believes that large-scale animal tracking data could be the key to improving this, and preliminary data suggests he might be right.
Researchers attached movement sensors to cows, sheep and dogs in an earthquake-prone region in Northern Italy. Several months later, they returned to remove the tags and collect the data on board. They found that the animals were unusually restless in the hours prior to an earthquake, providing the first empirical evidence that animals really can sense these natural disasters in advance.
“We are now starting to understand the ‘sixth sense’ of animals,” Wikelski says.
Far from being a supernatural ability, it’s born out of natural, physical principles, he says: “If you have interacting, intelligent sensors, you have emergent, novel properties – that’s the ‘sixth sense’ of animals.”
By tracking wild animals at scale, scientists can tap into this emergent sense to better understand and make predictions about the world.
ICARUS is the most ambitious wildlife-tracking project that’s ever been attempted and for the researchers involved in it, who’ve spent over a decade making the project a reality, the possible applications are almost endless.
With a global, interconnected network of animals, scientists and conservation workers everywhere will have access to the lives of wildlife in unprecedented detail. What secrets they’ll be able to uncover about the natural world, only time will tell.
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About our experts
Prof Martin Wikelski is Director of the Department of Migration at the Max Planck Institute of Animal Behaviour. He has received numerous honours, including Germany's Order of Merit.
Dr Jesko Partecke is a researcher at the Max Planck Institute of Animal Behaviour, specialising in ecology, evolution, and bird migration. His work has been published in journals including Ecology, Global Change Biology, and Frontiers in Zoology.
Dr Kate Mansfield leads the University of Central Florida (UCF) Marine Turtle Research Group, studying sea turtle conservation, behaviour, and migration, with a focus on nesting, juvenile stages, and offshore tracking.
