Aquatic Warblers successfully translocated to Lithuania

A pioneering project has shown promising results in the fight to save Aquatic Warbler, Europe's rarest songbird.

The translocation of dozens of broods of the sedge-dwelling passerine exceeded all expectations, with nearly all the young birds successfully released and researchers reporting unexpectedly high return rates.

Aquatic Warbler suffered catastrophic declines in the 20th century following habitat destruction and agricultural intensification across Europe, leading to its extinction in several countries.

Return rates of the translocated Aquatic Warblers exceeded natural levels (Lukasz Pulawski).

In 2018 and 2019, a total of 100 young Aquatic Warblers were taken from wetlands at Zvanec, Belarus. The birds were moved to the Lithuanian Žuvintas Biosphere Reserve as part of a groundbreaking EU-funded project led by Baltic Environmental Forum Lithuania.

Zvanec holds the largest population of Aquatic Warbler in the world, with approximately 3,000 singing males. The world population is estimated at between 11,000 and 15,000 pairs, but Lithuania now supports only around 1% of the global total.

The broods were collected when the young were six of seven days old, a stage at which they can be fed by humans and females are likely to lay a replacement clutch. Nests were moved overnight to Žuvintas, where they were hand-reared before being placed in an aviary and exposed to the sounds of any surrounding Aquatic Warblers, as well as recordings.

As soon as the young were able to fly, they were released. Almost all birds, 99 out of the 100 translocated, were released successfully.

Project leaders were hoping at least one translocated bird would be found again the next year, but at least 11 of the 49 birds released in 2018 returned the following spring, with several females going on to nest successfully. This is higher than the natural return rate for the species.

2020 saw the Aquatic Warbler population at Žuvintas reach a record high and three translocated birds were still surviving and returned to the site in 2021.

According to Ornithomedia, phase of translocations began in 2023 and will continue in 2024.