Somerset bittern survey underway

Somerset Wildlife Trust (SWT) has launched a survey of the county's Eurasian Bittern population.

The survey began on 14 March and will run for a month, concluding on 14 April. The most reliable way to monitor the species' numbers in the breeding season is to listen for the male's booming call which can be heard from up to 5 km away.

SWT said the number of bitterns on the Somerset Levels had risen over the last decade, with between 40 and 50 males now regularly being counted across its sites. The Avalon Marshes boast one of the biggest populations of the cryptic heron in the UK.

Somerset Wildlife Trust's survery of Eurasian Bittern ends on 14 April (Robin Lee).

Bittern boom

Mark Blake, SWT's senior reserves manager, said anyone who hears the sound in Somerset over the next month can log it online as part of Project Bittern.

"We're hoping it's going to be really straightforward and we're really keen to get as many people as possible around the county involved," he told BBC Radio Somerset.

The Avalon Marshes boast one of the biggest populations of bitterns in the UK.

Conservation success story

Bittern is thriving in Britain and has spread north in recent years. 2021 was a record year for the number of booming males documented in the country, and this came following years of steady increase.

The species was extirpated from the UK in the 1870s due to a combination of over-hunting for food and draining of their favoured wetland habitats for agriculture. The species returned to Britain in the early 20th century, and restoration of wetlands has allowed their numbers to more than double in a decade.