The Grey Heron is a large, stately bird which simply cannot be overlooked in the wetlands.
It may be observed year-round in the Donau-Auen National Park. In shallow waters it hunts its main staple, fish, but has been known to stalk mice in harvested fields. Generally highly adaptive birds, the Grey Heron requires for breeding quiet woodlands in which it can build its eyries in colonies. Thanks to reduced persecution, the Grey Heron population has largely recovered in Europe. Yet at present, the population is once again declining as a result of new persecution thanks to the "fish-eater debate" which has inflamed fishermen throughout Austria.
Description
The Grey Heron is an impressive bird. With a wingspan of around 170cm – equalling that of medium-sized eagles – it is especially noticeable when in powerful flight. The most important key to identification is that unlike the long-necked, long-legged birds of the Ciconiidae family such as storks and cranes, which fly with outstretched neck, the heron flies with a retracted neck. In flight, wings are high up and strongly bowed. Adults in particular are characterised by pale grey, sometimes bluish plumage which contrasts starkly with the grey-white underparts. Characteristic is the hoarse, croaking flight call ("kah-AHRK") which carries well. Juveniles can be readily differentiated from adults: the former have somewhat darker and dullish plumage (up to the winter of their second year), and adults have a white forehead and bright yellow bill which turns orange during breeding.
Distribution
Widespread throughout the entire Old World (Palearctic), up to Southeast India and Java; also native to the African continent, down to South Africa, albeit quite sporadically. In Europe, the range extends north to Norway. Less common in drier southern climes than in Central Europe. As a wetlands native, the Grey Heron is found in Austria in the major river valleys of the Danube, March and Mur. However, where big rivers, lakes or ponds may be found, it may settle less densely, as in the Waldviertel ("Forest Quarter"), along the rivers in the foothills of the Alps and even in the higher mountainous areas. In Austria, population density is considerably lower than in neighbouring countries. At present, there are only three colonies in the Danube wetlands; according to documentation provided by none other than Crown Prince Rudolph, there were considerably more Grey Herons in former times. Today, the regulated Danube offers far too few quiet islands with forest growth which could be used by Grey Herons as colony locations to build their nests far above reach from predators.
Endangerment and Conservation Status
After centuries of merciless persecution based on the misguided idea that these birds had somehow depleted fishing stocks, the Grey Heron has now been able to recover somewhat across Europe. And in Austria, the population had been increasing up until recently and former breeding areas were resettled. Yet a significant population decline in various areas has been charted recently. This is due to the ongoing and increasing persecution as part of the so-called "fish-eater debate". In addition to hunting of Grey Herons permitted by the authorities, illegal disruptions and even destruction of breeding colonies have taken place. These have led to fragmentation into smaller colonies and individual eyries, which more and more are not located in ideal environments such as near to major rivers, but are instead settled in less-suitable tributary valleys. Thus in retrospect it is clear that the 1989 decision to classify the Grey Heron as "potentially endangered" on the IUCN Red List – signifying a latent threat to the species in the form of human intervention – was entirely appropriate.
Behaviour
Grey Herons feed primarily on fish which are hunted either by laying in wait stock-still, or by carefully wading through shallow water. Whenever necessary, however, the bird will also hunt mice and amphibians on fields and in meadows. The most essential habitat requirement is however quiet woodlands, where eyries can be built in tall trees. Like other herons, the Grey Heron breeds in colonies and is extremely sensitive to disturbances. The adult predigests food in its crop and regurgitates it to feed the young (in fact, German slang for "to vomit" is "reihern", and has to do with the German name for heron, "Reiher"). As long as they do not freeze over, bodies of water, and especially rivers, offer sufficient nourishment for the birds in winter. The Grey Heron is therefore not purely migratory in nature: in the search for bountiful fishing areas, it will often move around without any specific direction, or will migrate simply to avoid the onset of cold (winter flight).
Special Characteristics
The Grey Heron plays an important role for other important species in the ecosystem made up by the wetlands and the marshy areas belonging to them. Other endangered large birds such as the Black Kite, Red Kite, White-tailed Eagle, Saker Falcon, Cormorant, and Black-crowned Night heron settle in or on the outskirts of Grey Heron breeding colonies. For this reason, the current persecution of the Grey Heron is especially problematic. As well, experts are united in their opinion that neither cormorants nor herons can in any way affect fish populations, much less endangered fish species, on natural bodies of water. The accusation that these two fish-eating birds are responsible for unrealistically major damage to fish populations has yet to be substantiated.