The boom is getting louder as researchers discover more bitterns in the wetlands of UK, since the heron's disappearance many years ago.
Bitterns are bright brown herons with dark streaks, flying on broad wings. They dwell on reed beds and feed on insects and fish by the waters' edges. They are very secretive and silent birds, and are hard to find by sight. However, the male bittern's booming mating call is loud enough to hear from up to 2km (1.2 miles) away.
The bittern's booming call is therefore what allows researchers to tally its current count.
Reed beds are grassy wet lands and are the bittern's natural habitat. Changes in the environment have, however, resulted in the drainage of the reed bed's waters and further, the drying out of the bittern's home.
In efforts to bring back the bitterns from their second extinction in the UK in the late 1990s, the Royal Society for the Protection of Birds (RSPB) initiated the conservation of reed beds in England and Wales. More homes started to welcome back the boomers - Ham Wall, Lakenheath and Ouse Fen.
Ham Wall. Created out of peat workings in Somerset in 1995, this paved the way for the boomer's first nesting in 2008. This year, researchers recorded a count of 17 bitterns.
Lakenheath. Carrot-field-turned-wetland in Suffolk also in 1995, this restored bittern home welcomed its resident's first boom in 2006, housed its first nesting in 2009, and counted six boomers this year 2015.
Ouse Fen. Converted from mineral workings in Cambridgeshire more or less 10 years ago, conservation scientists project the Ouse Fen to be the largest reed bed in the UK. Its first bittern boomed in 2012. Researchers tallied 10.
"In the late 1990s, the bittern was heading towards a second extinction in the UK, largely because its preferred habitat - wet reed bed - was drying out and required intensive management, restoration and habitat recreation. But thanks to efforts to improve the habitat, combined with significant funding from two projects under the European Union Life Program, the bittern was saved, and we're delighted that its success keeps going from strength to strength," says RSPB scientist Simon Wotton.
This year's findings counted 40 booming males in Somerset and 80 in East Anglia. From 140 boomers in 61 sites last year, the count has risen to 150 this year. More than 59 percent of the bitterns inhabit areas called Special Protection Areas or Special Areas of Conservation (also known as the Natura 200 sites), under the European Union's Birds and Habitat's Directives.
"The bittern is a species which proves that conservation can be successful, especially when you can identify the reason behind its decline and bring in measures and funding to aid its recovery," urges RSPB conservation director Martin Harper.