Eurasian bittern

Latin Botaurus stellaris (L.)
Estonian Hüüp

Also known as: great bittern

Status in Estonia

Breeding, migratory and a rarely wintering bird.

Description

The Eurasian bittern is a large, tawny stork. It is smaller than a grey heron but stockier, with a thick neck, fluffy neck feathers and short legs. It is rarely observed in flight, but in flight, wide wings are seen, a stout front body and stretched back legs. From a distance, it looks to be completely tawny, with the wing coverts only slightly lighter than the darker primaries. It is rarely seen on the ground, but its presence is typically indicated by its distinctive call.

Size

Body length 69–81 cm, wingspan 100–130 cm. Body mass 865–1940 g.

Similar species

Grey heron.

Distribution

The Eurasian bittern’s habitat includes most of Europe, with the exception of Ireland, Iceland, Norway and the northern parts of Finland and Sweden. In addition to Europe, Eurasian bitterns breed in North Africa and the northern and eastern parts of Asia. There is also a population of isolated Eurasian bitterns in South Africa. The Eurasian bitterns in Western and Central Europe are primarily sedentary, while the ones in Northern Europe are migratory. Most Eurasian bitterns that nest in Europe spend the winter around the Mediterranean Sea, with some also wintering in North Africa. The Eurasian bittern is an uncommon breeding bird in Estonia, found in places with more extensive reed cover.

Population

Estonia has 300–400 breeding pairs.

Occurrence in Estonia

Eurasian bitterns’ entry into Estonia differs from year to year and is mostly determined by the early spring weather. Typically, Eurasian bitterns arrive in the middle of March or April and depart in late September or early October. Only a few (1–10) individuals winter.

Diet

The primary diet of the Eurasian bittern is fish, specifically crucian carp, tench, European perch and northern pike. It occasionally eats frogs, tadpoles, newts, aquatic insects and mammals as large as European water voles. Young birds are fed mainly with tadpoles.

Habitat

It primarily inhabits the reed beds of inner bays, larger lakes and coastal lagoon. It has an extremely hidden lifestyle, hiding in the reed beds throughout the day and emerging at twilight.

Nesting

Typically, the Eurasian bittern returns to the same nesting site for years. The most desirable habitat is reed beds growing in water, where the edges are continually under water and dense bulrushes and reeds alternate with patches of open water. The male birds are the first to arrive at the nest and start making low-pitched calls. The male bird that arrives first is more likely to establish a larger harem. The male bird calls during the duration of the breeding season, which is about three months. Though the call is initially meant as a signal to female birds, it eventually serves the goal of protecting the territory. The female bird builds a messy nest up to half a metre in diameter on tussocks emerging from the water in dense foliage and lays 3–6 eggs. The female bird incubates for 25–26 days. Chicks leave the nest around 2–3 weeks old and learn to fly at two months old. The female bird feeds the chicks until they can fly, at which point the brood scatters and the chicks begin feeding on their own.

Conservation status and protection

It belongs to the protected species of category II. The primary threat is over-intensive reed bed management and a lack of appropriately sized reed beds. Disturbances (reed cutting) during the breeding season are also a threat to the species.

Distribution and population in Lääne County.

The Eurasian bittern inhabits reed beds that grow in shallow sea bays and larger lakes in Lääne County. The majority of Eurasian bitterns breed in the reed beds of Matsalu’s inner bay (approximately 25 pairs) and the Silma Nature Reserve (up to 10 pairs).

As a reed-dwelling bird, they are rarely seen, but they are vocal in the spring, from March to May. Their call, similar to blowing into a bottle, can be heard in Matsalu, including on the Penijõe hiking trail and the Silma Nature Reserve near Saunja Bay and the Sutlepa Sea. Eurasian bitterns vocalize most actively in the morning and in the evening.