Liada is a female eagle nesting in the Mid-Pripyat Nature Reserve in Polesia. She spends every winter in Zambia, in a tiny area of only 3 square kilometers. This is too small even for a Greater Spotted Eagle, but Liada is a hybrid between ​G​reater and Lesser Spotted ​E​agles. Typically, wintering​ ​​L​esser ​S​potted ​E​agles have several feeding sites located at a significant distance from each other. ​Because of this, ​vast wintering areas of tens of thousands of square kilometers are formed.

Wintering grounds of ​G​reater Spotted ​E​agles are much smaller;​​ however, they usually also reach dozens of square kilometers. It means that Liada is an exception to the general rule. Every day, she flies only a couple of kilometers from one part of the forest to another. How can she survive in such non-typical conditions? I had to dig ​deep​​ ​​into ​the internet to figure it out. Fortunately, this part of Zambia is well known to scientists and naturalists. The area belongs to the Kasanka National Park​,​ famous for its biodiversity. It is home to various species of bushbucks, blue monkeys, and about 400 bird species. And then I found out that one of the most famous natural “shows” occurs in Kasanka annually, and it attracts numerous tourists from around the world.

From​ the​ middle​ of​ October to late December, over 10 million​ ​of Eidolon​ ​​F​ruit ​B​ats (Eidolon helvum) congregate in Kasanka. All of them arrive​ in ​the wetland forest with ​a ​total area of about 2 ha​,​ thus forming the highest density of mammals in the world. Eidolon ​F​ruit ​B​ats are​ quite b​​ig​​​ ​​– their weight can reach 350 g. The enormous number of resting bats causes tree branches to bend and even break.

No wonder that the congregation of bats attracts numerous predators. The forest turns into a feeding ground for birds of prey. In addition, there are crocodiles, snakes and l​​eguans waiting for some unfortunate bat to come​ tumbling down​​.​

And what about our Liada? Is she part of this natural spectacle? Yes, she is! She arrives in Zambia in late October, simultaneously with the bats, and then visits the bat forest almost every day. Obviously, Liada like many local predators, feeds on this mysterious natural phenomenon – ​the ​mass congregation of Eidolon ​F​ruit ​B​ats in the same place.

Isn’t this impressive? Liada nests in Polesia, looks and behaves just like dozens of other​ ​​G​reater ​S​potted​ ​​E​agles, but at the same time she is the link that connects us to an outstanding natural phenomenon in a different part of the globe. What secrets ​do ​other ‘ordinary’ ​G​reater ​S​potted ​E​agles​ ​​hold​? We can only guess and hope for new, unexpected discoveries.

Male Greater Spotted Eagle Dzimon was captured and tagged with a GPS-tracker on the 9^th of July 2020, in the eastern part of the Almany Mires in Polesia, not far from his nest. He wasn’t much different from other birds of the species: he hunted properly and raised a strong chick by autumn.

​​But ​​​​​something strange began to happen with Dzimon following spring, after he had returned to Polesia from his wintering site near the border of Sudan, Ethiopia and South Sudan. Having arrived ​at​ his nest, Dzimon his female in ​the​​​ company of another male. The couple had already renewed the old nest with fresh branches and lined it with green leaves to make​ the​​​ eggs​’​ incubation more comfortable.

The female’s behavior was not at all strange. She never knows if her old partner will return, and therefore she accepts courtship from any male who likes her. Usually, the new male leaves the nest in case the female’s old partner returns. At first it seemed like that was happening. Dzimon and the female visited the nest together, and the alien disappeared. But this only lasted for a couple of weeks.

On the 27^th of April, Dzimon flew to the edge of his hunting territory and stayed at the same place for three days in a row. Unfortunately, the camera trap at the nest was not working at that time, and we don’t know what happened ​​​i​n the nest right before he left. But the eagle was confused, it was noticeable in his behavior. It seemed that he didn’t know what to do next. So, three days later, he took to the air and left those places. He never returned to his female and the future chick.

Dzimon started wandering. At the beginning, he headed to the north to hunt in an agricultural area near the town of Turau/Turaw, which was rich in field mice. Well refreshed, the bird headed east in a week’s time, reaching the town of Pietrykaw 70 kilometers away. Then he flew back crossing the river Ubarc and the Almany Mires and found himself on the bank of the Jaselda river not far from the town of Pinsk. On the 16^th of May, Dzimon surprisingly headed to the town of Pinsk and stayed there, in the urbanized area, for more than a month! It looks like he was hunting right in private gardens on the outskirts of the town. In late June, the eagle changed his location again and flew to the Belarusian-Ukrainian border, where he stayed until the beginning of the autumn migration.

And what about the nest and the female? The new male that appeared in spring was still there. He spent the summer feeding the female and their chick that grew up and left the nest successfully in August. But why did Dzimon leave his nest? We can only guess. Maybe he lost the competition with a stronger and younger male, or maybe he guessed somehow that he would have to feed someone’s else chick… The bird’s thoughts will remain a secret.

During the spring migration of 2022, Dzimon arrived​ ​​in​ Polesia very late – on the 19^th of April. It was one of the latest known dates for the return of a Greater Spotted Eagle. He rushed directly to his old nest. Perhaps he was still hoping for a happy family life? Apparently, no​ ​​o​ne was waiting for him at home. Having spent about 20 minutes there, he flew on into the depth of the Almany Mires. Over the next month, Dzimon tried to settle down there. But he didn’t succeed, since the area was already shared by other nesting birds. Gradually, they drove him out further south, to Ukraine, where the density of the species is not so high. He spent most of the season close to the village Stare Selo in Ukraine. On the 25^th of July, Dzimon flew kilometers to the south-east, to​ the​ Zhytomyr region, where he died three days later. No​ o​ne knows what happened to him. The Ukrainian experts only found a tracker and the remains of Teflon straps that used to fix the device on the bird’s back. This was the end of Dzimon’s journey, during which he never found a new home.

In 2021, the female Greater Spotted Eagle of unusual light colour returned to her nest on the 2^nd of April. This individual is very remarkable: Greater Spotted Eagles with pale morph are very rare in the European part of their range, and this very bird became the first Greater Spotted Eagle with such a phenotype observed in the Belarusian Polesia. Will her chicks inherit the pale morph? We can’t predict that.

The male Greater Spotted Eagle – with rings on his legs and a GPS transmitter on his back – appeared two days later, on the 4^th of April.

Greater Spotted Eagles often build their nest on a branch fork high above the ground, so that their home is hidden behind dense foliage. Typically, the same nest is used by the same pair of birds for several years in a row. Having returned home, the birds immediately started working hard improving the old nest. They carried new branches to their nest for more than 2 weeks. Compare its appearance before and after the renovation!

In late April, the female Greater Spotted Eagle spends a lot of time in the nest: she is about to lay eggs. A Greater Spotted Eagle usually lays from 1 to 3 eggs, with a break in time. And here it is! We observe the first egg on the 30^th of April. On the 4^th of May we see two eggs in the nest already.

Now, the incubation of the eggs begins. It lasts from 40 to 44 days on average. Previously, researchers supposed that only the female stays in the nest throughout the entire incubation period. But the camera traps pictures show that the birds take turns incubating the eggs. The female spends more time in the nest. However, the male often gives her time to hunt and stretch her wings. It is quite cold in early May, only 5-10 °C. The female spreads her feathers to keep herself and the eggs warm.

The male eagle feeds the female while she incubates the eggs. Information on the composition of the Greater Spotted Eagle’s diet is very important for the study and conservation of this species. And camera traps give us a chance to observe what the birds eat! This time, it’s a vole. Small rodents are common prey of the Greater Spotted Eagles.

At the beginning of June, our Greater Spotted Eagles look forward to the most exciting event of the nesting season: their chicks are about to hatch. The female’s powerful paws with sharp claws allow her to tear apart her prey easily. But look how delicately she holds the egg!

Finally, the long-awaited moment comes: the first chick hatches on the 8^th of June after 5 weeks of incubation! The parents celebrate with big catch: this time, it’s a hare. While the female is busy with the prey, we can see the first hatched chick clearly – it is one day old!

On the 12^th of June, we see the second chick free of its shell. But will it survive? Greater Spotted Eagles have a strong tendency to cainism: a second-hatched chick often dies within the first two weeks, and its death is directly or indirectly caused by the elder.

At about two weeks old, the chicks of the Greater Spotted Eagles are quite active, stretching their wings and crawling. The adult birds have to keep an eye on them all the time so that they don’t fall out of the nest.

Meanwhile, the male has to spend a lot of time hunting to provide food for himself, the female and their chicks. The camera trap captured rodents and a mallard chick among their prey. The female feeds the chicks in turns tearing the prey into small pieces. The older chick is bigger, stronger and more assertive. But the adults pay equal attention to the second-hatched one, too. Obviously, it has a good chance to survive!

The older chick is nearly 3 weeks old, with the first feathers visible among the down covering its body. Remarkably, the parents started leaving the chicks alone in the nest for short periods! The fast-growing chicks need a lot of food, so the adults have to spend a lot of time hunting. This time the male caught a weasel.

As the camera trap photos prove, the diet of the Greater Spotted Eagle is quite varied. In the photo below, the female seems to reproachfully look at the chicks as they turned away from the fish. But the next day we see a chick trying to eat a vole on its own while the adults are away!

When raising chicks, adult Greater Spotted Eagles permanently renew their nest with fresh branches of oak, alder and birch. In this way, the birds cover the remains of prey and droppings, keeping the nest clean.

It’s early July, and the first-hatched chick is one month old. The second one is just a few days younger, but the difference is still noticeable – they are growing so fast! Both chicks continue receiving equal care and nutrition, and it’s very likely that both will survive.

By mid-July, the Greater Spotted Eagles chicks have grown quite big and strong and no longer need the constant presence of their parents. Ornithologists choose this time to replace the batteries and SD cards of the camera trap on the nest and ring the chicks. Look, one of them has a new ring on its leg! The chicks often flap their wings in training for their first flight. But the female still cares for them tirelessly. The camera trap caught her shielding the chicks from the sun with her wings.

Most often, Greater Spotted Eagles hunt small mammals. However, the most part of the biomass consumed by these predators consists of birds. Sometimes, even large birds: the bones identified on these camera traps images belonged to a heron!

At the beginning of the nesting season, we guessed whether the new chicks of the pale female would be of the rare pale or typical dark colour. In the second half of the summer we can clearly see that they have inherited the morph of their father and have grown up to the typical dark colour  of the Greater Spotted Eagle. However, there are known cases when chicks of two different phenotypes have been observed in the same brood!

By mid-August, the breeding story is over: the fledglings left the nest! They were last seen by our ornithologists in early September, when the young birds are usually quite independent. This is a remarkable story: both chicks survived and grew up! We hope that they are still well and that one day the rings will tell us more about them thanks.

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Those carrying out biodiversity surveys in Polesia must not be squeamish. It is a wilderness area of superlatives: half the size of Germany, the predominantly peatland landscape stretches from Poland through Ukraine and Belarus into Russia. Rivers in their natural state, overflowing their banks in spring, meander through a mosaic of alluvial forests, bogs, oxbow lakes, floodplain meadows and mires. 

Such large contiguous habitats have largely given way to agriculture in other parts of Europe. And these wet and boggy habitats are difficult to traverse. While our colleagues wade slowly across the mires to count rare birds of prey such as the Greater Spotted Eagle or set up camera traps to study wolves and lynx, swarms of mosquitoes and other insects are their faithful companions. 

One of the main goals of our work in Polesia is to identify areas that are worth protecting. A better understanding of where there are gaps in protection and where priority areas lie will help us to support and justify requests to expand existing protected areas and designate new ones. Biodiversity and the presence of strictly protected species are among the key criteria. 

However, population surveys are usually time-consuming. Additionally, nocturnal animals, such as insects or bats, which are difficult to find, are often overlooked, even though they usually have a high conservation status. Studying smaller animals such as bats, rodents and insects using conventional methods takes a lot of time, effort, patience and financial resources. Therefore, in Polesia we have turned to a new promising instrument for biodiversity research: acoustic monitoring. Bats and other species can now be identified using sound recordings. 

In the largest systematic survey of species diversity in Ukrainian and Belarusian Polesia to date, we carried out what is known as passive acoustic monitoring for two years. We recorded bats, birds, small mammals, bush crickets and some large mammals over an area of about 50,000 square kilometres, comparable in size to Slovakia. In this area, the recording devices were set up at 500 sites for four nights at a time. Thousands of hours of animal sounds have been recorded – day and night, in dense forests and extensive bogs and in every direction within a hundred metres of the recorder. 

The current result is around three million recordings with around 500,000 animal sounds. It would take years to filter out these animal sounds from other environmental noise and identify them individually. Therefore, our project partners at the British Trust for Ornithology have developed an automatic sound classifier. Similar to the mobile phone app Shazam, which can identify pieces of music based on a melody fragment, the new sound classifier is able to match recordings of animal sounds to certain species. The algorithm analyses the spectrogram, i.e. the visual sound image of the recording. It then  searches for typical patterns according to known parameters and provides information about the type of sound recorded. 

In this way, we can now automatically classify over 50 species of bats, birds, bush crickets and small mammals. To be on the safe side, these are then manually checked and the algorithm is improved where necessary. This allows us to record many species simultaneously, from the Great Grey Owl (Strix nebulosa) and the Pygmy Shrew (Sorex minutus) to bush crickets such as the Great Green Bush Cricket (Tettigonia viridissima). 

This method of recording and monitoring the species is non-invasive as the animals are not disturbed compared to traditional methods. Bats, birds and insects do not have to be caught with nets and then examined and identified manually. In addition, acoustic monitoring is cost-effective as it allows the recording of different groups of animals simultaneously, and large amounts of data can be collected in a relatively short period compared to conventional recording methods. 

The main objectives of the acoustic monitoring are to systematically map biodiversity throughout Polesia, identify habitats of particular importantance to different species, identify priority conservation areas and assess the impact of human activities such as drainage, fires and road construction on the biodiversity. The species lists also serve as a basis for formal applications to extend protected areas. 

— Your recent study analyzing the patterns of landscape fires in Polesia combines both conventional field surveys and innovative approaches that require special knowledge and skills to systematize and analyse large amounts of data. What specialists did you have to involve in your team to achieve the desired result? 

— We had specialists who analyse fire relationships from satellite data, classify and utilise satellite data,  and conduct statistical analysis and modeling of large data sets. Collaboration of people with special knowledge in different disciplines is very important for producing good and well-rounded research. 

— Is it an easy task to “translate” the conclusions of data scientists into the language of environmental science? 

— It was quite easy. In fact, environmental science and data science are very intertwined, so we understood each other very well.

— This study is the first one of its kind for the Polesia region. Did you face any difficulties along the way due to the specifics of the landscape itself or data related to it? What solutions helped you to overcome such difficulties? 

— One of the biggest challenges was getting an accurate land cover map for Polesia. Existing regional maps only covered small areas, often not digitised and sometimes costly to access. Large free land cover maps (European or global maps, processed through machine learning) were inaccurate, or didn’t include important land cover types in Polesia like bogs and mires. We overcame this by building our own land cover map, by using ground-truthed data from our colleagues and then our own machine learning algorithms to process satellite data.

— Did you use a large amount of the necessary data from the ground for this research? How would you estimate the accuracy of the final results and are you satisfied with it?

— As for the amount of ground-truthed data, we used over 2000 polygons of manually verified training data. The accuracy of the land cover map was about 80%. We tested this by holding back a percentage of the training data and then checking this with the classified map. It’s always nice to increase accuracy, but overall we were satisfied with this.

— How can the methodology of this study be applied to other regions or landscapes? In this case, what basic principles will remain the same, and what aspects of the study will have to be changed and adapted?

— The fire database is global so this data can be extracted anywhere. The big limitations are the land cover maps that cover a region, these are often readily available in Europe or North America, but less so in other continents and regions. 

— Are there any general recommendations for collecting preliminary data from the ground and creating a land cover map? What parameters and characteristics of a landscape, in addition to the space distribution of different land cover types, should be taken into account in order to most accurately identify the patterns of landscape fires?

— Training data evenly distributed across the region of interest is needed, as there can be spatial patterns of landcover types. For example, areas close together are more likely to be similar due to climate, geology, etc. Climate features (temperature, wind, precipitation) and topography are just some natural factors that are very important in identifying fire patterns. Human factors, such as settlements, land use intensity and land management (grazing intensity, farming practices, wetland drainage) should be certainly taken into account. 

— Looking back, is there anything in your work that you wish you had done differently?

— It would have been great to have the outcome of building the land cover map of the project area as a priority at the start of the ELP project. This way we would have had more training data earlier in the process.

— What do you see as the prospects for the further application of this research? 

— There are still many questions to answer. Do restored wetlands actually burn less? How long does it take them to get wet enough? How does this interact with the effects of climate change? It would be great to test our hypotheses on real restoration events.

The top image features an area in Almany Mires damaged by fire in 2018. Aerial photo by Ivan Murauyou. 

The delegation’s members discussed the cooperation prospects with executives and employees of Cheremskyi, Rivnenskyi and Poliskyi nature reserves as well as the Chornobyl Radiation and Ecological Biosphere Reserve. In all these protected areas there are drained mires with good prospects for successful restoration – its feasibility was assessed by experts of the Michael Succow Foundation.    

An important task was to listen to opinions of different groups of stakeholders. The position of specialists of the nature reserves is clear: they know the benefits of the mires’ restoration better than others and therefore highly appreciate the international assistance in organizing this work and demonstrate their willingness to cooperate. Their support is extremely valuable, just like the one of the State Agency of Water Resources of Ukraine.  

At the same time, the opinions of the local communities are not always unambiguous. On the one hand, a stricter protection regime and rewetting of drained areas may mean certain limitations for economic activities of the local residents. On the other hand, lack of pure water caused by drainage is the argument that makes many people change their minds in favor of the mires’ restoration. 

Members of the foreign delegation accompanied by Ukrainian experts visited Cheremskyi, Rivnenskyi and Poliskyi nature reserves to learn more about them on the ground. Each of the reserves has its peculiarities, and the areas to be restored have different degrees of disturbance, spatial organization and features of drainage systems.  

It has been decided that prior to the construction works, experts will conduct a one-year-long hydrological monitoring as well as peat layer analysis. It will allow assessing the present water levels in the project territories and then evaluating the efficiency of the restoration. The proposed monitoring methodology and further modeling based on the data obtained was elaborated and successfully tested by Polish experts.   

During a round-table session that took part at the National University of Water and Environmental Engineering in Rivne, experts discussed the value, present state, threats and prospects of the Polesian wetlands. Among other topics, they touched upon the historical importance of mires as natural barriers during military conflicts which is unfortunately up on the agenda today. We hope that this aspect will lose its urgency very soon. However, mires in Polesia, being a source of drinking water for millions of people, an effective carbon storage and a hotspot of biodiversity, are worth being restored and preserved for generations to come.

Fires are of great concern to policymakers in the region due to the economic and health costs, and a lot of resources are used to suppress fires during hot and dry years. There are potentially natural solutions to fires, however, that could also benefit birds, biodiversity and climate issues. These ‘nature-based’ solutions include restoring drained wetlands. In this study, freely-available satellite data were used to explore the prevalence of large fires and the factors causing them. This allowed researchers to explore whether restoring the landscape’s wetlands could reduce the increasing risk of large, damaging fires as the climate changes.

This study identified five fires reaching more than 100 km², a threshold often used to classify ‘megafires’. Frequent spring and summer fires predominantly started in agricultural areas, where farmers burn the land to clear it, both before planting and following the harvest. However, these fires often spread into neighbouring peatlands and floodplain meadows, endangering threatened wildlife, such as the Greater Spotted Eagle and Aquatic Warbler, and damaging a globally important carbon sink.

The largest fires burned in native deciduous forests, threatening protected old-growth oak and beech forests, which are more vulnerable and less likely to recover than more fire-adapted trees. Overall, more than one fifth of protected land burned. This is compared with 8% of unprotected land. One fire reached 97 km² and burned significant areas of the Chernobyl Exclusion Zone, where radioactive contamination from the Chernobyl 1986 disaster is highest, and where the impacts of large fires on human health may be particularly severe.

The results of the study suggest that landscape restoration in Polesia’s wetlands would help to limit the spread and intensity of unnaturally large, damaging fires, while reinstating natural, periodic low-intensity fires, providing ecosystem benefits and supporting long-term carbon storage.

Throughout Europe, including in Polesia, years of drainage for agriculture and commercial forestry has created overgrown, drier landscapes that are more susceptible to fires. This study showed that open peatlands, meadows, and deciduous forests were far more likely to burn when moisture conditions in the soil and litter were low. In contrast, peatlands were very unlikely to burn under high moisture conditions. Preserving and restoring large, intact, well-hydrated peatlands would help to create natural barriers to large, severe fires, while reinstating periodic low-intensity fires. Doing so would provide ecosystem and conservation benefits, support long-term carbon storage and help tackle climate change, and protect human lives.

Greater Spotted Eagles are returning to their nests in Polesia from the Balkan Peninsula, Israel, South Sudan, Zambia, and even South Africa. Every year, they fly thousands of kilometers to reach their breeding and wintering sites. Their journey is full of the expected difficulties and threats. However, they face another trial: the war is now right on their migration route. Polesia’s Greater Spotted Eagles faced this for the first time last spring. Ornithologist Valery Dombrovski, who has been researching Greater Spotted Eagles for decades and keeps a close eye on the GPS-tagged birds, shared some of his observations with us…   

“Spring migration in 2022 was quite typical in terms of dates and average duration. But our close attention was riveted to Greater Spotted Eagles nesting in the Chornobyl Exclusion Zone – they had to cross the Kyiv region where active hostilities were going on. One of them, a male by the name of Borovets, was the first to start on his way. He followed his traditional route through Odessa and Cherkasy regions. Borovets approached Kyiv on the 29^th of March, at the very moment when the Russian troops withdrew under attack by the Ukrainian forces. Borovets stopped on the left bank of the Dnieper River to wait out bad weather: the sky was cloudy, and cold rain had started. The eagle spent the following day at the same place. Sounds of explosions were heard from far away – Kyiv was still being shelled. Could the bird tell these sounds from spring thunder? It is not really possible. On the 31^st of March, when the sun shone again, Borovets rushed further north.   

He flew above the eastern outskirts of Kyiv and then along the Kyiv Water Reservoir. With his sharp vision, it is likely he could observe long columns of military vehicles retreating from Kyiv, probably an uninteresting sight for the bird. Foul weather forced Borovets to stop again, now further up the reservoir, and about 20 kilometers from the Belarusian border. This time, he stayed in one place longer – from the 31^st of March until the 3^rd of April. It was quiet: explosions were no longer audible. The Russian troops had retreated from the Kyiv Region and the Chornobyl Exclusion Zone. Borovets fed happily on birds and mammals hiding in riverside reeds, and  visited the farmlands around the neighboring villages.  

On the 4^th of April, a fair wind blew from the south and drew the clouds away. Just 4 hours later, the eagle reached his nest in the Polesie State Radioecological Reserve. Fortunately, the helicopters that were flying back and forth above the reserve every day during the past month had already followed the rest of Russian military units. Thankfully, Borovets could occupy himself with his “family” concerns. During the remainder of the 2022 season, he successfully bred a chick. 

A female eagle, named Elleni, arrived in Ukraine much later. On the 4^th of April, she stopped shortly in the Odessa Region. By the end of the next day, thanks to favorable weather, Elleni reached the western outskirts of Kyiv. There, she stayed overnight alongside the Irpin river. The fighting had stopped there several days earlier.  The bird showed no unusual behavior. On the morning of April 6, she flew further north. Her flight path crossed now infamous places: Irpin, Gostomel, and Bucha where terrible massacres took place. Luckily, birds cannot understand such horrors. The next day, Elleni reached her nest, nearby to the nest of Borovets. Elleni’s breeding season ended with its own sadness, as her chick died in the middle of summer from an unknown cause. 

In spring 2022, other Greater Spotted Eagles from Polesia flew across the Western part of Ukraine where there were no active battles. All the birds reached their nests successfully. The fastest one was Blond, on the 17^th of March, he was already in his nest in Almany Mires. Most birds arrived later, in the first week of April. Vialuta was the last to return, arriving home on the 20^th of April.  By the way, this is the latest date of the end of spring migration for five years of observations.” 

The war in Ukraine gave ornithologists not only food for thought, but also material for scientific research. We expect a research paper to be published analyzing the war’s impact upon the migration patterns of the Greater Spotted Eagles. In the meanwhile, though we can’t stop the war immediately, we hope for a safe migration back home for the birds – wild Polesia is waiting for them.  

The accident at the Chornobyl Nuclear Power Plant in 1986 was one of the worst nuclear disasters that ever happened. When speaking about the long-term consequences, people naturally tend to refer to the negative impact on human health and on the environment, caused by the heavy radioactive contamination. However, there is at least one additional long-run side effect of this tragic occurrence that is often overlooked: the accident paved the way for an unparalleled case of large-scale rewilding of a settled region. On about 470,000 hectares of land that had formerly been densely populated and used for intensive agriculture, human activities ceased almost completely from one moment to the next. The people who once called this region home had to move away, the farmland was abandoned, and drainage canals were locked to prevent the spreading of wildfires and contaminated water. But the retreat of the population did not mean that all life had left the area. Nature took its chance and began to reclaim the territory, at its own will and pace.

This rewilding process has been observed by researchers for more than two decades. The findings are impressive: From 1999 to 2017, the wetland area increased by 680% and forest area by 14%. Now, more than 30 years after the accident, the territory looks like Polesian wetland habitats in northern Ukraine or southern Belarus, with typical seasonal floods and large mires.

The transformation of the animal communities was expected to be enormous after the massive decrease of human impact. Over a period of 22 years – from 1998 to 2019 – ornithologist Valery Dombrovski monitored population sizes, species composition, and habitat changes of birds of prey nesting in the Chornobyl Exclusion Zone. Parts of this study were supported by the Polesia – Wilderness without Borders project. The study area spans over 14,700 hectares of former farmland that had been intensively used until 1986.

During the study period 13 breeding species of daytime predators were recorded, and both species composition as well as the number of individuals changed significantly.

For instance, the globally endangered Greater Spotted Eagle (Clanga clanga), which relies on wetland habitats to hunt and is very sensitive to human disturbance, had been locally extinct in the area at the time of the nuclear catastrophe. 33 years later, in 2019, four pairs were recorded at the study site, and at least 13 pairs were known to be nesting in the whole Belarusian part of the Chornobyl Exclusion Zone. Today, this region is the only part of the world where the population of this rare species is growing. The increase of wetland areas alongside low levels of anthropogenic influence in the Chornobyl area created favorable living conditions for the Greater Spotted Eagle, which may help save this threatened species from extinction.

Another (locally) endangered raptor that reacts sensitively to human presence is the White-tailed Eagle (Haliaeetus albicilla). Before the nuclear accident, this bird could not be found in what is today the Chornobyl Exclusion Zone.  Only in 1992, White-tailed Eagles were first sighted here, and by 2010 their number had increased to 20 pairs. Unlike the Greater Spotted Eagles, White-tailed Eagles are non-migratory, so the availability of prey in winter is crucial for their survival. And here is how the true value of rewilding reveals itself: a functioning ecological community has returned to the area, composed of various species that sustain and support each other. Along with the birds of prey, top predators like wolves as well as their prey species (such as deer and moose) established viable populations, so that there is enough carrion for the White-tailed Eagle to make it through the cold season.

While the Greater Spotted Eagle and the White-tailed Eagle profited from the abandonment of the area, the scientists also observed decreasing populations of certain bird species. This applies to raptors that prefer hunting in farmland, such as Montagu’s Harrier (Circus pygargus), Lesser Spotted Eagle (Clanga pomarina), Honey Buzzard (Pernis apivorus), and Common Buzzard (Buteo buteo). Interestingly, at the beginning of the monitoring work in 1998, the population sizes of these species in the Chornobyl Exclusion Zone were much higher than the regional average.

Overall, the study shows that the passive rewilding of ecosystems is a complex and lengthy process. Some species needed nearly two decades to build stable populations, and others, like the Greater and Lesser Spotted Eagle, are still adapting. The Greater Spotted Eagle started colonizing the Chornobyl Exclusion Zone only 15 years after humans had left. Therefore, a long-term dynamic monitoring is the only way to assess the restoration process and the development of species composition and population sizes. But it has already become obvious that passive rewilding can bring European lowlands back to a near-natural state – both on the ecosystem as well as on the biodiversity levels.