Bitterns at Leighton Moss: Boom, Hide, and Wait

25 February 2026

The bittern's boom

The bittern's booming call is produced by the male from February to June to advertise territory and attract females. The call is a deep, resonating 'oom' repeated several times, almost like a foghorn. It can carry for up to two kilometres in still conditions. The sound is so distinctive that once you have heard it you will never mistake it.

Peak booming activity is at dawn and dusk in February and March. On still mornings the boom seems to come from everywhere and nowhere — the sound disperses through the reed as much as it travels through the air. Stand quietly at the edge of the reedbed at dawn in early March and wait. You will hear it.

Britain had fewer than 30 booming males in the 1990s after decades of habitat loss and water quality decline. Active conservation work — reedbed restoration, water management, and the creation of new reedbed habitat — has brought the population back to over 200 booming males. Leighton Moss was one of the sites that maintained breeding bitterns through the worst period.

Seeing a bittern

Seeing a bittern is harder than hearing one. They spend most of their time concealed in the reed, moving through the stems on foot rather than flying. They are extraordinarily well camouflaged — the vertical streaking of the plumage matches the reed stems and a standing bittern simply disappears.

The most reliable sighting opportunity is a flying bittern. In the breeding season, males fly between reedbed patches at dawn and dusk, moving low over the reed tops. From the main hides at Leighton Moss, these flight views are the standard sighting. The Grisedale Hide and the Lower Hide overlook reedbed edges where bitterns sometimes hunt or stand in the open.

In cold winter weather bitterns become more visible as they are forced to hunt more actively to maintain body condition. On frosty mornings in December or January, bitterns sometimes stand at the reedbed edge for extended periods. This is the best chance of prolonged close views.