Lake Neusiedl and its reed belt

Nature Reserve Zone - southern part of Neusiedler See

Neusiedler See is the westernmost steppe lake in Europe and Austria's largest lake. Its 178 km² reed belt is the second largest connected reed bed in Europe. The lake and its reed belt cover in total about 320 km², of which 4/5 are on Austrian, and 1/5 is on Hungarian territory. This lake - referred to as "Austria's strange guest" by Franz Werfel - harbours a large variety of rare animals.

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During the Würm glaciation (about 115.000 to 10.000 years ago) the area of the Neusiedler See was as high as the Parndorf Plateau. The formation of the lake began about 13.000 years ago, in the succession of tectonic movements.

During the first depressions, the water body in the Hanság area was formed. The depression of the south area formed the bottom of the present lake, but caused the silting up of the shallower Hanság. 
Lake Neusiedl is therefore much younger than the lakes in the Alps and the Prealps, which formed during the last ice age.

The ground water is in no way connected to the Neusiedler See. Even the approximately 47 million cubic metres of surface inflow from the surrounding areas that supply the lake make up for only a small percentage of the water lost through evaporation every year.

Einserkanalschleuse beim Mexikopuszta (Fertöujlak)

The largest part of the water volume of this 320km² lake comes from precipitation, which leads to extreme fluctuations of the water level, sometimes resulting in complete desiccation. 

Only during the past hundred years the Main Regulation Channel has enabled the regulation of the water level, at least to prevent flooding. The lock, modernised in 1992, is on Hungarian territory and can not be used to increase the water level.

Dry areas in the reedbelt, Summer 2002

In the past, natural fluctuations of the water level had different dimensions - the lake dried out several times and extended to more than 500km². 

A few figures to illustrate the size of the 1.5 metre shallow steppe lake:

  • An increase of the water level by one centimetre corresponds to 3 million cubic metres of water (the daily requirements of 15 million people) . Due to a length of 36 km and the earth curvature, the centre of the lake is 27 metres higher than the northern and southern lake shore.

  • the average water temperature is 11°C and can reach up to 30°C.

  • the maximum salt concentration can surpass 2000 g/m³ in summer.

  • the reed belt, that is up to 5 km wide, covers a total area of 178 km²

The reedbelt - a mosaic of habitats

The reed belt of the Neusiedler See is the second largest connected reed bed in Europe; only the reed bed of the Danube delta is larger. The Neusiedler See reed belt has only developed since the mid 19th century. Until then, large reed beds only existed in the southeast and the Hanság. Today, a total surface of 178 km² encloses the lake. A series of low water levels after the Main Regulation Channel was built, but also the nutrient intake by agriculture and the surrounding villages have favoured the growth of the highly competitive reed.

Although this one plant species is very dominant, the reed belt offers a large variety of habitats. There are channels and open waters, reed beds of different age and structure. 

Nutrients and pollutants are deposited due to the protection from wind. The reed belt acts like a natural clarification plant, biodegradation takes place. The reed prevents the wind from moving the water. That is why the water in the reed bed is coloured brownish and explains the high visibility depth, compared to the open water of the lake.

Grass Snake(Natrix natrix)

There are insects and their larvae everywhere you look - in the air, on top or inside the reed, on and under the water surface. You can find a multitude of small crustaceans, water snails, and spiders. The reed belt harbours an immense amount of invertebrates. 

These animals and many plants serve as food for many other animals. The European Tree Frog or the Fire-bellied Toad and many other amphibians, as well as the Ring Snake call the reed belt their home.

Most of the fish use the reed belt not only as spawning ground; pike, catfish, ruffe and carp spend almost all their lives in the reed belts. 

Hidden in the reed undergrowth live Pygmy Shrews, Miller's water Shrews, European water Shrews and the vole; a relic from the last ice age. Landward reed beds give shelter to roe deer and deer.

Great White Egret (Casmerodius albus)

However, the reed belt is most important to the birds. Colonies of different ciconiiformes (long-legged wading birds) like Great White Egret, Grey Heron, Purple Heron, Night Heron, and the Little Egret, as well as the European Spoonbill are located mostly in the Nature Reserve Zone.

Thousands of songbirds build their nests in the reed belts such as the Thrush Reed Warbler, Sedge Warbler, Savi's Warbler, Reed Bunting, Blue Throat as well as different crakes like Bald Coot, Water Rail, Gallinule and Spotted Crake. Internationally important are the populations of the Moustached Warbler, the Little Crake and the Bearded Tit.

Habitat preferences of birdspecies in the reedbelt

The reed belt is the perfect breeding area for many duck species. The population of the endangered Ferruginous Duck might be of international importance, the exact number of breeding pairs is difficult to identify due to the size of the reed belt.
Sicherlich von internationaler Bedeutung sind die Bestände von Mariskensänger, Kleinem Sumpfhuhn und Bartmeise.

Marsh Harrier (Circus aeroginosus)

The Neusiedler See is a very important nesting area for the Greylag Geese; there are about 400 breeding pairs in the Neusiedler See area. This is the biggest population in Austria. The population of the Marsh Harrier which also nests in the reed, is the biggest in Central Europe. In addition to its significance as a nesting area, the reed belt is an important resting area for migrating birds and wintering birds. 

Other birds, such as the Blue Tit, Great Tit, European Robin and Chiffchaff that usually live in wooded areas, take advantage of the rich food supply in the reed belt during winter. Barn-swallows, House Martins and Sand Martins often hunt in the reed area in late summer. Sometimes there are Kingfishers to be seen at the channels of the reed belts.