Boom in mating calls of Britain’s loudest bird signals successful breeding year

Conservationists recorded 24% more male bitterns doing their mating ‘booming’ noise in 2023 than five years ago

Britain’s loudest bird has had a very successful breeding year, with 24% more male bitterns recorded doing their mating “booming” noise in 2023 compared with five years ago.

Conservationists for the RSPB recorded 234 males across England and Wales including at 11 new sites. The member of the heron family was mating in areas of new habitat created at the RSPB site Leighton Moss and on the Isle of Sheppey.

The birds are hard to spot, despite their large size, because they are secretive and successful at camouflaging themselves among reeds. However, during mating season the male birds make a distinctive “boom” noise to attract a mate. Each “boom” is different depending on which bird is making it, so the males can be counted by following their individual voices. The noise can be heard up to three miles away.

The birds are losing their reedbed habitats due to sea level rise caused by climate breakdown, so it is important that inland areas are created for them to breed in. They depend on areas with tall reeds and water so they can move, camouflaged, to hunt fish, insects and amphibians.