The Bittern species is a large bird of the heron family, living in wetland habitats. Yet it looks completely different to most herons, with pale, buff-brown plumage covered with dark streaks and bars. It flies on broad, rounded, bowed wings and is the bird everyone hopes to see when they visit the RSPB Minsmere reserve.
Bitterns are elusive and well camouflaged. They hide in the dense reed beds, popping out to catch eels, fish and amphibians, and quickly darting back under cover. This makes them a secretive bird and extremely hard to spot in their environment with their unique plumage. Typically, it’s their call, the Bittern boom, that announces their hidden presence. In fact, the Bittern is the UK’s loudest bird.
It is the foghorn-like call that gives the Bittern its name. The word bittern is Anglo Saxon, derived from the Latin butio (bittern) + taurus (bull).
As a volunteer at RSPB Minsmere, I love talking about Bitterns to the visitors. My appreciation has grown from my very first encounter with Bitterns. Their future has not always been assured. In the late nineteenth century, they were close to extinction. Even now, they have an Amber conservation status.
Bittern concerns
In 1997, there was a study conducted to confirm the number of booming male Bitterns here in the UK. The result was a worrying one indeed. There were only eleven booming males left in the country.
This sparked a six-year study on how to maintain and improve their habitat, increase their numbers in Britain, and secure their future in the UK.
In the beginning of these studies and surveys, eight sites in the UK were selected to study the Bitterns. Minsmere and Leighton Moss were two of those chosen to do the biometric studies. The researchers captured the Bitterns in specially designed nets. The scientific study noted their measurement and weight, feather growth, and general condition.
Since those studies in 1997, the recommendations from the findings have been implemented – habitat reclamation, reed bed management, and a successful conservation plan led by RSPB and Natural England. The number of booming male Bitterns now in the UK has grown from eleven recorded in 1997 to 283 booming males in 2024 – a substantial rise in the population in 27 years.
Witnessing something special
In 2018, my fascination with Bitterns led me to begin a personal study, collecting data and especially learning about their behaviour. One day, I witnessed a male and female Bittern in a courtship – very rarely seen by humans – and to date I have seen this twice.
I was all alone, and in the quiet, a female Bittern flew in and landed in front of the hide. She pointed her head skywards, spiralled her neck feathers out, and then lowered her wings down to the ground like a pterodactyl. She stayed still, and within 30 seconds, a male Bittern flew in.
He proceeded to bulk himself up, expanding and exposing his beautiful mating plumage. The female submitted to him by posturing with her neck feathers retracted. She bent forward with her neck lowered; and he began his display by walking around her, shaking his wings, and occasionally letting out a boom.
For over 30 minutes he continued displaying to her. His initial mounts seemed unsuccessful – he kept sliding off. But one of the four mounts must have been a successful coupling as they then relocated behind some flag irises, and started preening together.
What a unique moment – one I will never forget.
RSPB Minsmere’s Bittern record
Recently, we have added Bittern sightings books in two hides for visitors to record their own sightings. This encourages visitors to get involved and become part of citizens’ science experience. At the end of the year, we will have records of what the visitors have seen. This will augment the sightings of volunteers to give a more complete record, and help expand the understanding of this fascinating, elusive, and secretive bird.
The aim is to include more information events/days about Bitterns next year. RSPB Minsmere hopes to offer guided walks around the reed beds and hides in the non-breeding season cycle, which is autumn to late winter.
When to see and hear a Bittern
One of the best times to see and hear a male Bittern booming, is in the breeding season from March to May. The male Bittern calls out from the reed beds with his booming sound to attract the females, especially in the early morning light and late evening – although individuals will boom all day.
The male’s call can travel over two kilometres. For him to achieve this boom takes a great deal of energy. He gulps in air and puts his head low to the ground, which helps him force out the booming call. A fully-grown adult male will usually be able to boom up to five times, one after the other. Younger males can manage between one and three booms at a time.
Every year, RSPB Minsmere conduct a booming male Bittern count in early spring to May in order to ascertain the number of booming males on site. Then, a spring/summer feeding and flight count records the number of nesting females on site. From this, we can work out the total possible number of nests that are active on the reserve. Similar counts are made on all reserves.
These studies, conducted every year, are critical to keep track of the Bittern population in the country. Without them, it would be difficult to determine the success of conservation efforts. And everyone should have a chance to see these incredible and elusive birds — an experience you’ll never forget.
The author maintains a record of Bittern observations with more photos.
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