In the past, the Hanság was part of the Neusiedler See. It silted up, it formed a fen. In the 18th century, the road between Pamhagen and Fertöd (Esterháza at that time), divided the area in two. Today, the mostly drained part on Austrian territory harbours rare animals like the Great Bustard (Otis tarda), which is the heaviest bird able to fly. The Short-eared Owl (Asio flammeus) and the Montagu's Harrier(Circus pygargus) breed here.
The formation of the Hanság area is inseparably linked to the development of the Neusiedler See. The first lake-bed was located here. The discovery of ostracods in 12,000 year-old sediment supports that theory.
In the 16th century, as the Hanság was still part of the lake, people started to drain the area by building several channels. In the 18th and 19th century there was only a swamp left. From 1855 until 1886 the fen was gradually drained by channels; hay making replaced fishing as the main income. Higher spots were used for extensive livestock farming. Until 1870 peat cutting was common. This peat cutting formed basins that were quickly overgrown with reed, sedges and willow scrub. Today, most of these areas are afforested and only few parts of the former bog-alder forest still exist.
The Main Regulation Channel (built in 1908) and other drainage channels made the saline lakes (Lacken) disappear in the Hanság. Fen meadows, reed beds, and pasture land (dry and semi-dry grassland) near the villages were used as farmland. In 1970, there were still some 1.500 hectares of fen meadows, reed beds and marshland. Today only 200 hectares remain, of which the so called “Komassantenwiesen” (National Park territory since 1993) with 140 hectares constitute the largest part of integral meadowland.
The Hanság, the silted up part of the Neusiedler See, extends from the villages of Pamhagen, Tadten and Andau in Austria to Osli and Lébény in Hungary and covers a total area of 460 km². The territory in the province Burgenland, called Waasen, has a total surface of 70 km².
Until about 100 years ago, the Hanság was one of the most important wildlife areas in Central Europe. There lived 14 different species of birds of prey here and 8 species of ciconiiformes (long-legged wading birds). This abundance has diminished over time, but the area still harbours many globally endangered species. The living conditions in these habitats have changed due to human interference, like drainage and reforestation. The Austrian part of the Hanság is known for the Great Bustard (Otis tarda), who in the past had been numerous in Seewinkel and has now found its last retreat here.
Hunting of the Great Bustard was suspended in 1969 because the population had dropped dramatically. In 1973, its nesting areas were declared an exclusive nature reserve. The population has increased again in the past years. Other birds, like the Montagu's Harrier (Circus pygargus), the Short-eared Owl (Asio flammeus) and the European Curlew (Numenius arquata) breed on the Austrian side. Efforts were also taken on the Hungarian side to preserve and reconstruct habitats that attract different herons, cormorants (Phalacrocorax carbo) and many other water birds.