The last of their kind

The Aquatic Warbler is the rarest songbird in Europe. As part of an international EU LIFE project, we are working with numerous partners to do everything we can to save the species from extinction.

The sun is setting and an ornithologist is standing in a field.

Evening atmosphere in the Ukrainian marshes: at this time of day, the chances of hearing and perhaps even seeing a Aquatic Warbler are at their highest.

© Justine Vansynghel/EuroNatur

It is already late in the evening, but after a hot day, the temperatures are still sweltering. The rubber boots squelch with every step; moving around in the Ukrainian marsh is exhausting. Finally, there is the fatigue of the long evenings out in the field.

Despite her exhaustion, EuroNatur project manager Dr Justine Vansynghel is very happy. She has just seen a “lifer”. This is the term used in birdwatching circles to describe a species that you have seen for the first time in your life. And Justine's “lifer” is a very special species: the Aquatic Warbler, Europe's rarest songbird.

  • Secretive and under threat

    Aquatic warbler in the reeds

    Aquatic Warblers are skilled climbers.

    © Žymantas Morkvėnas

    Open wet areas with low sedges and sawgrass: where in Europe can this combination still be found in plentiful quantities? Habitat destruction is the main reason for the decline of the Aquatic Warbler (Acrocephalus paludicola) in recent decades. Like all warbler species, this strikingly striped songbird is difficult to catch sight of. It is most likely to attract attention through its song in the evening hours. Today, the Aquatic Warbler lives only in a few areas of Eastern Europe, mainly in Lithuania, Poland, Belarus and Ukraine. The last German breeding population on the Oder River died out in 2014. To support the former ‘sparrow of the fens’, an international LIFE project has been launched, in which EuroNatur is playing an important role. One of the geographical focal points for this ambitious species conservation project is north-western Ukraine.

In search of the rare bird

ornithologists in Ukraine

An international team of experienced ornithologists is searching for a needle in a haystack—or rather, an Aquatic Warbler in the marsh.

© Kevin Guille
habitat of the Aquatic warbler

Flat, wide land: typical landscape in Prypiat-Stokhid National Park

© Justine Vansynghel/EuroNatur

Dr Justine Vansynghel is travelling through the Prypiat-Stokhid National Park with numerous Ukrainian ornithologists and volunteers from all over Europe. Divided into six teams of two, they walk transects in the national park. A transect is a defined survey route with several measurement or observation points.

The team members stop at intervals of about 100 metres and listen. Justine and her companion, Kevin Guille from France, listen but initially without success. They hear and see several other bird species such as short-eared owls, rosefinches, Savi’s warblers and sedge warblers, the last of which does resemble the Aquatic Warbler, but Acrocephalus paludicola is nowhere to be seen.

As dusk is already well advanced, Justine and Kevin are not expecting to catch sight of the bird. The two have almost reached the end of their transect when they suddenly hear a grating ‘trrrrr’ sound, immediately followed by a series of whistling tones. ‘The song sounded a bit like a sleepy Sedge Warbler,’ recalls Dr Justine Vansynghel. ‘Kevin and I were really surprised because the habitat wasn't ideal, with lots of charred bushes. But an Aquatic Warbler was singing out of one of them, and Kevin, as a recognised expert, had no doubts. And then the singing male even showed himself. It was a great moment seeing one of Europe's rarest birds for the first time in my life,’ Justine enthuses.

The warbler sings

Listen to the chirping song of Europe's rarest songbird, recorded on the evening of June 4, 2025, in Prypiat-Stokhid National Park (turn up the volume!)

 

International species conservation project

Aquatic Warblers prefer to sing at dusk, and since dusk comes late in spring and early summer, the evenings out in the field are quite long. As well as Justine, the few full-time staff members in Ukraine are supported by numerous volunteers from Ukraine and abroad. This support is extremely important, as our Ukrainian partners are working at full capacity. 

‘It was inspiring to see how committed the volunteers are to protecting this European natural heritage and its endangered species. With support from other European countries, we wanted to show that nature conservation must not be neglected, even in times of war.

Selfie of an ornithologist in the field
Dr Justine Vansynghel, Project Manager for Migratory Bird Protection

The entire LIFE project is as international as the ornithologists and bird experts involved. Together with seven partners from five different countries, we launched the nine-year ‘LIFE4AquaticWarbler’ project in October 2024 to protect the Aquatic Warbler. The aim of the project, partly funded by the EU, is to halt the decline in subpopulations in Poland, Lithuania and Ukraine and to rebuild the extinct populations in Germany and Hungary. The aim is to restore the Aquatic Warbler's breeding area to a total of almost 4,000 hectares. 

Translocation for species conservation

These are ambitious goals, and to achieve them it is firstly important to know the location and size of their current breeding populations. It is for precisely this reason that monitoring is being carried out in the Prypiat-Stokhid National Park. The large protected area in the far north-west of Ukraine, together with the populations on the Belarusian side, forms one of the last large breeding areas of the aquatic warbler. The aim is, with the help of our partners, to restore the bird to its previous breeding areas.

Similar translocations have already been successfully implemented in Lithuania in recent years. To this end, Baltic bird conservationists collected nests with hatched chicks of the Aquatic Warbler that were already under threat from mowing and raised them in breeding stations. Once they had survived the nestling stage, the young birds were placed in aviaries in the middle of the areas to be repopulated. There, they were able to slowly acclimatise to their new environment before being released into the wild after a few days. At the end of the summer instinct led these migratory birds to spend the winter in West Africa and then return to the reed beds where they had been released the previous year.

Increasing drought

The Prypiat-Stokhid National Park would actually be an ideal area for a stable source population from which individual nests could be taken. However, the impressions that Dr Justine Vansynghel brought back from her trip to Ukraine were cause for concern. Compared to spring 2024, significantly fewer Aquatic Warblers were recorded this year.

This is quite possibly due to the drought. There has been too little rainfall throughout the winter and spring. In April 2025, a large fire raged in the dried-up marshes, burning an estimated 1,000 hectares of reeds and marshland. ‘The fire was probably caused by illegal slash-and-burn practices. Fanned by the dry conditions, the fire then developed into a wild fire,‘ Justine suspects. The consequences were still visible at the beginning of June. ‘It will probably take another one to two years before we can begin translocating some Aquatic Warbler chicks in Ukraine. In the meantime, the habitats must be upgraded to improve the chances of a successful relocation," says the biologist.

Landscape in Ukraine

The impression is deceptive: although it had rained shortly before the excursion to the aquatic warbler habitat, the preceding weeks and months had been far too dry overall.

© Justine Vansynghel/EuroNatur

Good for the climate and other species too

Protective measures such as raising the water levels of marshland areas, removal of trees and bushes and close-to-nature management are designed to ensure the future survival of the Aquatic Warbler in the Prypiat-Stokhid National Park. Moreover, they also benefit a number of other animal and plant species that have become rare in Europe.

‘The biodiversity was impressive,’ Justine sums up. ‘During the day, we were able to observe many birds that have long been extinct in Central Europe or have at least become extremely rare. When, after dark, the evening chorus of birds from the reed warbler and grasshopper warbler families gave way to the night-time calls of the corncrakes, I was completely entranced.’

Diversity of birds in the Prypiat-Stokhid National Park

But it is not only animals and plants that benefit from these measures; we are also protecting the climate. When sedge marshes are destroyed, large amounts of carbon dioxide stored in the peat are released into the atmosphere. However, if we and our partners restore water levels in these wetland habitats, they can once again act as veritable water and carbon dioxide sponges. 

With the passionate commitment of EuroNatur and its partners, we are tackling two of the major crises of our time: species extinction and the climate emergency. If we succeed in Eastern Europe, it will send a strong signal to the rest of the world that committed species and climate protection is possible even in politically difficult times.

Author: Christian Stielow

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