Why a new approach was needed

Until now, chicks were sourced mainly from the world’s largest Aquatic Warbler populations in Zvaniec (Belarus) and the Biebrza marshes (Poland). With cooperation with Belarus suspended and war reshaping conservation work across the region, Biebrza National Park has effectively become the only large donor population inside the EU. This creates a bottleneck. If translocation expands—especially as countries such as Poland and Germany prepare to restore small populations—Europe cannot rely on one donor area alone. 

With the species in dramatic decline, we must safeguard as many nests as possible—especially those likely to be destroyed by early mowing or intensive grazing. This is the logic behind our new method. By focusing on broods that are genuinely at risk in the donor landscape, we achieve two goals at once: we rescue nests that would otherwise be lost, and we reduce the demand for chicks from Biebrza—the only large EU donor population. In other words, a single approach delivers two conservation gains. 

With the species continuing to decline overall, the logic is shifting toward approaches that both support restoration and help save nests that would otherwise be lost. That is why the “rescue translocation” approach tested in 2025 may become increasingly important in the future beicoming standard procedure. 

“Rescue translocation” from the Nemunas Delta

In 2025, Lithuania tested a this idea: sourcing chicks from a smaller but stable population in the Nemunas Delta, estimated at about 200–300 singing males, and selecting only nests facing a real risk of destruction due to early mowing or intensive grazing. In practice, translocation became a rescue measure, saving broods that would likely not survive. 

This approach was more demanding than collecting from a large donor area. With fewer nests available, teams had to invest more effort to find them, and selection depended on fast coordination with land users. The team needed to contact farmers immediately and confirm whether mowing or grazing would happen and when. This added a strong social dimension to fieldwork, and farmers’ responses could vary once a nest was found on their land, making trust and negotiation part of the process. When risk was confirmed, nests sometimes had to be removed almost immediately, increasing transport effort and resulting in more variable brood ages, but ensuring that effort focused on broods that were genuinely at risk. 

A success story in tough conditions

The 2025 season was unusually challenging. Prolonged cold and dry conditions delayed nesting, and females remained hidden longer than usual, making nest finding even harder for this famously secretive species. Still, once chicks began to hatch, the team located nests under threat and moved them to safety in Žuvintas. 

Although the season stretched from one month to nearly two, the results were strong. Eleven nests with fifty-three chicks were transferred from the Nemunas Delta to Žuvintas and fifty-two chicks were successfully raised and released—an overall release rate of 98.1%. The team experienced one painful loss during routine weighing when a chick escaped and died after hitting glass—an emotional reminder that even well-run conservation work carries risk and that caution should always be in a highest level. 52 chicks were moved to outdoor aviaries and released using a soft-release approach, returning to the aviaries for food and shelter as they adapted. Importantly, one of the Aquatic Warblers raised and released in Žuvintas was later observed during autumn migration in Rotterdam, confirming that released birds can survive and continue their long journey. 

Why this matters for Žuvintas—and beyond

Žuvintas remains highly vulnerable. In recent years, only six to twenty singing males have been observed there. Habitat still exists, but the population was no longer regenerating naturally, putting it at real risk of disappearing. Translocation offers a way to rebuild numbers while habitat management continues. 

The broader lesson from 2025 is that translocation can do more than move chicks. If it prioritises broods likely to be lost anyway, it can also reduce pressure on donor populations, particularly in landscapes shaped by intensive farming. That principle becomes crucial when the EU has only one major donor population left and when even that stronghold can decline sharply after a single extreme season. 

Team, welfare, and data improvements

Scaling up translocation remains demanding. It requires skilled nest-search teams, daily coordination with farmers and land managers, intense work providing live insect food from early morning until late evening, and strong veterinary-informed health-care routines. It also depends on clear roles and a steady team mindset, because fatigue can undermine consistency. 

One positive outcome of 2025 was capacity-building. More people were trained and involved, including volunteers and the core team, strengthening continuity and knowledge transfer. The team also improved data collection and analysis by developing new tools to record feeding time and care routines more accurately, increasing both efficiency and monitoring quality. 

What comes next

Lithuania’s 2025 experience suggests that rescue translocation from smaller populations can be a worthwhile investment, both ethically and practically, when done carefully and in close cooperation with land users. If it proves impossible to gather enough nests this way in future seasons, a backup plan remains: additional chick collection from Biebrza National Park. But the direction is clear. In a changing world, conservation must be flexible, targeted, and rooted in collaboration—while maintaining the highest standards of animal welfare and scientific care. 

This approach is already proving transferable: the rescue-based sourcing principle tested in Lithuania is planned to be replicated in Poland this year in a new area, showing that the method can travel across borders—just like the birds it aims to protect.