Conservation report
Loss of fen mires poses risk to Europe’s rarest songbird
Where does it live?
On fen mires, a type of wetland dominated by sedge grasses. Its global population declined over the past century by 95 per cent. Today, there are 16,000 singing males. The majority of the population breeds in Poland, Ukraine and Belarus. The species acts as a health indicator for its habitat: we know that if the aquatic warbler is thriving, then other species found in the fen mire are also doing well.
What is interesting about this bird?
Their mating system is unique amongst European songbirds. Aquatic warblers do not form pairs and are not territorial. Males don’t help with rearing the young, instead spending the breeding season singing and mating with multiple females. The females are able to do everything themselves due to the abundance of insects on fen mires. Sometimes they nest closely together in a quasi-colony, and each brood can contain offspring from many fathers.
Why is their population decreasing?
Habitat loss due to drainage and decrease in mire maintenance are the key reasons. In Belarus, over a million hectares have been drained since the 1960s – an area that used to be home to up to three million aquatic warblers. When grass cutting stops and fen mires are abandoned, they eventually become forests. In EU countries, farmers are paid €300 per hectare per year to cut vegetation if the aquatic warbler breeds on their fen mires.
Can we expand its habitat?
Wetlands were restored in several countries, but the aquatic warbler has not returned. Last year, we launched a translocation project. We took 50 chicks in Belarus and moved them to a restored fen mire in Lithuania. We hoped they would imprint the new location as their breeding site. Of the 49 birds we released, nine males came back to the new location this year, and at least two females were raising nestlings this summer. Because of the high success rate, we have released 50 more this July, and the project will expand into more countries in the future. Maria Antonova
ALEXANDER KOZULIN
is head of the international department at the Scientific and Practical Centre for Bioresources, National Academy of Sciences of Belarus.
FIND OUT MORE
Aquatic warbler conservation: meldine.lt/en