White-tailed eagles with backpacks put researchers on the right track
May 17, 2026|Written by Lise Bundgaard
Written by Lise Bundgaard
Researchers have climbed down into eagle nests in South Greenland to attach GPS backpacks to young eagles. The goal is to shed light on the mysterious lives of these birds.
On a rocky ledge in South Greenland, a white-tailed eagle gazes out over the landscape. It is Greenland’s largest bird and an animal whose cultural and spiritual significance in Greenland cannot be overstated.
Yet there is still much we do not know about it.
“We lack very basic knowledge about white-tailed eagles in Greenland,” says Nicholas Per Huffeldt, senior scientist at the Greenland Institute of Natural Resources.
He is leading a study aimed at uncovering two things: how the eagles move across the landscape, and what they eat. Authorities will use this information to make decisions about how best to manage the species.
To learn more about the eagles, the researchers headed into the fjords of South Greenland to visit their breeding grounds.
White-tailed eagles fly over the research expedition in South Greenland. Photo: Knud Falk.
“We lack very basic knowledge about white-tailed eagles in Greenland”
– Per Huffeldt
Visiting 11 eagle chicks
Last summer, Nicholas Per Huffeldt, his research colleague Knud Falk, and master’s student Mael Perroud traveled between Qaqortoq and Narsarsuaq in search of eagle chicks.
As adult birds are shy and difficult to approach, the researchers work with the chicks in the nests.
It was not an easy task, but they located 11 suitable chicks.
It was no simple task.
Not only can the nests be difficult to find, but the researchers sometimes had to rappel down steep cliffs to reach them. It required patience and skill.
“The chicks are strong, so you must be careful. Many people think the beak is the most dangerous part, but it’s actually thetalons. They can lock in place and be very hard to get loose again,” says Nicholas Per Huffeldt.
Once the researchers reached the nests, they attached small solar-powered GPS transmitters to each chick – a kind of backpack that weighs almost nothing. After some time, it falls off on its own.
The researchers also collected samples from the beaks, talons, and droppings before heading home again.
Master’s student Mael Perroud and Nicholas Per Huffeldt collect samples from the eagle chicks’ talons. Photo: Knud Falk
Eaglets in the nest. Photo: Nicholas Per Huffeldt
Mael and Nicholas in the boat during fieldwork. Photo: Knud Falk
Backpacks map the Eagles’ routes
Back in his office in Nuuk, Nicholas Per Huffeldt and his colleagues have been able to follow the birds’ movements on screen.
The GPS backpacks send data every two or three days when the birds are within network range. Over time, the points form a pattern of routes and resting places.
There has long been an assumption that young white-tailed eagles, shortly after leaving the nest, spend more time inland. With the new data, researchers can now test that assumption.
“Many people think the beak is the most dangerous part, but it’sactually thetalons. They can lock in placeand bevery hard to get loose again” – Per Huffeldt
Do white-tailed eagles eat lambs?
The samples from beaks, talons, and droppings reveal what the chicks ate in the days before the researchers visited the nests.
In the lab, researchers examine the samples. They identify DNA traces from prey animals and compare them with a database to determine what the chicks have eaten.
In the 1970s, ornithologist Frank Wille observed that white-tailed eagles mainly took fish, but also smaller animals such as gulls and fox cubs.
“With the DNA method, we can for the first time get a reliable and more detailed picture of their diet,” says Nicholas Per Huffeldt.
And then there is the question that concerns sheep farmers in South Greenland: To what extent do eagles eat lamb? Researchers do not yet know, but they hope to have some answers by late summer as their work progresses.
Facts about the white‑tailed eagle research
Researchers from the Greenland Institute of Natural Resources are tracking young white-tailed eagles in South Greenland using GPS backpacks and, in collaboration with researchers from Université de Neuchâtel in Switzerland, conducting the DNA analysis to understand where they fly and what they eat.
The project is supported by the Aage V. Jensen Foundation, the Greenland Research Council, the Swiss Polar Institute, Basler Stiftung für biologische Forschung, Sophie Danforth Conservation Biology Fund, Société Zoologique de Genève, and Fonds des donations de l’Université de Neuchâtel.
The study of the eagles’ diet will conclude in 2026, while the movement study will continue as new chicks are equipped with GPS backpacks.
Master’s student Mael Perroud and researcher Knud Falk collect samples from the eagle chicks’ talons. Photo: Nicholas Per Huffeldt.
A truly unique species
The white-tailed eagle in Greenland is a unique subspecies found only in this country. This gives the authorities a special responsibility to protect them. Today, the eagle is listed as vulnerable on Greenland’s Red List of rare, threatened, or locally extinct species.
“There are still major gaps in our knowledge. Because the population is genetically isolated from other white-tailed eagle populations in the world, it’s especially important to understand it better. Yet we actually don’t know how many eagles live in Greenland,” says Nicholas Per Huffeldt.
The last nationwide count took place about 40 years ago. This project may therefore be an important first step toward ensuring the best possible management of the species.
As the eagles glide over the fjords with their tiny backpacks, a more detailed and updated picture of the white-tailed eagles’lives in Greenland forms – a picture that will provide missing answers to researchers, authorities, and sheep farmers.
The article’s main photo was taken by Nicholas Per Huffeldt.