Botaurus stellaris
A bird of mystery, the Bittern stalks through reedbeds and rarely breaks cover. Once pushed to local extinction, their numbers are increasing, although you are still far more likely to hear one of these unusual birds than see it.
Bittern
Juvenile Bittern
Bittern standing on a branch
Bittern looking for prey
Bittern portrait
Bitterns are large, stocky herons with buff-coloured plumage broken by dark, bold streaks and faint barring. Their most distinctive features are a dark cap and stripe from the bill to their throat. They have short but seemingly oversized yellow legs and feet, straight, pale beaks and small eyes.
Female Bitterns are difficult to distinguish from males, although they are generally smaller. During the breeding season, males develop light blue lores (the area between the bill and eye), while females have grey lores. Juvenile Bitterns are similar to adults but have paler caps and less heavily streaked backs.
Bitterns are unlikely to be confused with any other UK heron species if seen well.
Bittern in natural habitat
The Bittern is a large but compact member of the heron family. They usually appear relatively short-necked but can extend their neck to a surprising length when striking at prey.
Bitterns measure 64 to 80 centimetres in length. Their legs are heavily built and much shorter than other species like the Grey Heron and Little Egret.
Bitterns weigh anything from 650 grams to just over two kilograms. Males are the heavier sex, and females grow a little over one kilogram (1150 grams).
The Bittern has a wingspan of 1.25 to 1.35 meters.
Bittern in-flight over meadow
The Bittern produces a unique booming call unlike any other you are likely to hear in the United Kingdom. The call usually consists of two to four low-pitched notes repeated at intervals of a second or two. They also make softer contact calls and a single noted ‘Kaa’ flight call.
Bitterns boom most frequently in the spring breeding season, although some males begin as early as late January. They are most vocal between April and June.
The Bittern’s booming call can be heard from three to five kilometres (up to three miles) away in settled conditions. The best time to listen for this impressive call is often in the quiet hour of dawn.
Bitterns are one of the world’s loudest birds and are considered the loudest species in the United Kingdom. Their far-carrying call serves to advertise their territory to potential partners and defend it against other males.
Bitterns are carnivorous birds. Eels and other fish are their principal prey, although they also hunt for frogs, insects, rodents, reptiles and small birds in and around the water. They use their excellent camouflage and a quick strike to catch their target and then swallow it whole.
Fish is the most important component of the Bittern chick diet, although they also eat other small animals like frogs, birds, and rodents. The female feeds the chicks by regurgitation without the help of the male.
Bittern taking-off with fish in its beak
Bitterns are restricted to fresh and brackish water wetlands. They require dense flooded Phragmites (Common Reed) reedbeds for nesting with small open areas where they can hunt for fish. They occupy various lowland wetlands in the non-breeding season.
The Bittern breeds in scattered wetlands across England, particularly in Kent, East Anglia, Somerset, Lancashire, and Yorkshire. They are more widespread in winter when non-breeding birds may be seen in suitable habits in much of England, parts of Wales and eastern Scotland.
Bitterns spend most of their lives stalking through reedbeds. They are shy birds that rarely fly for long distances or perch in conspicuous places. Bitterns can swim well, although they prefer to walk on matted reeds or through shallow water.
Bittern in natural habitat
Bitterns are rare in the United Kingdom, with an estimated breeding population of about 227 pairs in 2019. However, these low numbers represent a conservation success story since their recovery from local extinction in the 1800s.
Bitterns returned to breed in the UK in the early 1900s but struggled to establish themselves and dropped to just 11 calling males in the 1990s. They have rebounded in the last decade or so, and their numbers continue to rise.
Despite their growing population, Bitterns remain a very challenging target for UK birdwatchers. They are shy and blend in perfectly among the dry brown reeds where they live. Visit wetlands at the following sites for your best chance of a sighting:
Bittern camouflaged in amongst the reeds
Bitterns can live for over eleven years, although their typical lifespan is probably closer to four. These are rare and elusive birds, so accurate measures of their longevity are difficult.
Adult Bitterns have few predators, although their eggs and chicks could fall prey to a variety of predators, including mink, fox, and Marsh Harrier.
Bitterns in the United Kingdom are protected by the Wildlife and Countryside Act 1981.
Bitterns are rare and localised in the United Kingdom, but they are not endangered. These elusive waterbirds have a wide distribution range on three continents and are assessed as a ‘Least Concern’ species on the IUCN Red List.
Bittern feeding on fish
Female Bitterns build their nests among standing reeds in flooded wetlands. The nest is a round platform of reed stems arranged just above the water line.
Bitterns nest in the spring and early summer in the United Kingdom, from April to June. These birds are ready to breed at a year old and produce a single brood each nesting season.
Bitterns usually produce four or five olive-brown eggs, each measuring approximately 53 millimetres long and 38 millimetres wide.
Bitterns do not mate for life. Some pairs are monogamous, but often a single male with a prime territory will mate with several females in a single season.
Bittern nest with five eggs
Bittern parent feeding young at the nest
Bitterns are generally solitary creatures. The males are highly territorial and will engage in vicious fights to defend areas from two to fifty hectares. These powerful birds have sharp bills, and these disputes may be fatal.
Bitterns may be active at any time of day or night. They sleep among reeds and other wetland vegetation.
Bittern standing in reeds on one leg in wetland
Bitterns are sedentary in the United Kingdom. However, populations in continental Europe and Asia are migratory, and some birds from countries like Sweden, the Netherlands, Belgium, and Germany overwinter in the UK.
Bitterns are native to the United Kingdom. They were extinct as a breeding species for a few decades around the late 1800s but have since recolonised, and their population continues to grow.
Bittern in-flight
Bitterns are rare visitors to Scotland. They do not nest there, but it is hoped that their breeding range may expand northwards in time.
The low light of dawn and dusk provide the best chance of spotting the Bittern. These shy birds rarely break cover and generally fly for short distances, dropping quickly out of sight.
The Bittern’s booming call can be heard by day or night, although their ‘Kaa’ flight call is more likely to be heard after dark.
Scientific name:
Botaurus stellaris
Other names:
Eurasian Bittern, Great Bittern
Family:
Herons, storks and ibisesConservation status:
Amber
Length:
64cm to 80cm
Wingspan:
125cm to 133cm
Weight:
650g to 2kg
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