The fate of Aquatic Warblers in the face of war: an international expedition in the Ukrainian wetlands

International expedition in the Polesia wetlands of Ukraine

International monitoring in the Polesia wetlands of Ukraine

In June 2025, a joint international expedition took place in the Ukrainian Polissia region to assess the status of the Aquatic Warbler (Acrocephalus paludicola)—Europe’s rarest songbird and a globally threatened species.

Researchers conducted the first-ever detailed monitoring of the Aquatic Warbler in the Ukraine almost after a decade. The most important site for the species in the country – the fenmire Birky, located between the Prypiat and Tsyr rivers near the village of Birky, within the Prypiat-Stokhid National Nature Park in Volyn was monitored.

The team consisted of 15 experts and volunteers from Ukraine, Lithuania, Germany, France, and Belgium. The expedition was led by Dr. Žydrūnas Preikša (Lithuania), a longtime member of the International Aquatic Warbler Conservation Team. Ukrainian participants received hands-on training in internationally standardized bird monitoring and habitat assessment techniques.

Conservation under pressure

In 2018 the Birky fer

mire hosted 400–450 singing males. However, the 2025 expedition recorded a sharp decline—only about 20 singing males were detected, and the suitable nesting habitat was limited to approximately 200 hectares. The area had been heavily degraded: 88% of the fen is now overgrown with willows and reeds. A recent spring fire further damaged the landscape.

Researchers monitored singing males during evenings on 1–2 km transects and surveyed other wetland species in the early mornings. They also documented the significant transformation of vegetation and identified a range of associated bird species, including Common Snipe, Great Snipe, Common Crane, and others like Savi’s Warbler and Common Rosefinch.

Dr. Preikša described the scene as bleak: “I returned from Ukraine with a heavy heart. It wasn’t just the visible signs of war—it was also the condition of the wetlands so vital for the Aquatic Warbler. Vast sedge meadows are now overtaken by shrubs, some scorched by recent fires. The region is exceptionally dry.”

Laying the groundwork for recovery

Though not directly hit by military action, the region has been affected by the war. With many residents gone, grazing and mowing have stopped—leading to unchecked vegetation growth. The expedition highlighted the urgent need to restore habitats and engage local communities.

This mission also marked the start of long-term ecological monitoring. Entomologists installed Malaise traps to assess insect populations—an essential food source for the Aquatic Warbler. These studies will continue until the end of the project, allowing scientists to track how conservation actions impact the bird’s environment.

Initial habitat restoration works will begin in autumn 2025, focusing on removing shrubs and reeds that are “eating up” the species’ habitat.

Hope in unity

This expedition underscores that even amid war, conservation can continue. It brought together specialists and volunteers across borders—united by the common goal of protecting biodiversity and giving the Aquatic Warbler a fighting chance.

The final data from the monitoring is still being processed, but one thing is clear: the path forward requires cooperation, swift action, and commitment to restoring the fragile wetlands of Polesia.

The actions descibed took place in Ukraine as part of the cross-border project “LIFE4AquaticWarbler”.