Having just departing Juodkrante towards Nida, but not mounting up to the steep Hill of Ram yet, another hill is aspiring among the old woods – the Hill of Herons, which received its name from the settlement of grey herons and grand cormorants that settled nearby. This is one of the biggest settlement of these birds in the whole Europe. According to the data of 2000, the settlement amounted to 582 couples of grey herons and 1,361 couples of grand cormorants.
It is unlikely to answer the question, when the herons settled in the neighbourhood of Juodkrante. In the middle of XIX mentury, they were a common element of everyday life. It can be said with a confidence that these leggy birds had lived in XVII century or even much earlier.
What did stimulate the herons to resettle their nestplaces from the northern to the southern neighbourhood of Juodkrante? Historical sources report on their battle with an aggressive “gooks” – the cormorants. Cormorants (Phalacrocorax carbo L. or Carbo cormoranus), otherwise known as marine ravens ”Corvus marinus”, had appeared in Juodkrante in 1803. They settled beside the herons and started to occupy their nests. Gradually, the herons were driven out to the edges. They began to migrate to the south of Juodkrante. In 10 years, two separate settlements of herons and cormorants emerged on the southern and northern border of Juodkrante.
The battle of cormorants and grey herons
O. Glagau also describes the battle between the cormorants and grey herons, which ended with the win of cormorants that drove the grey herons out for some time.
Cormorants moved their settlement to the south beside the herons. This time humans intervened in the relations of herons and cormorants. Considering recommendations of local forestry officers and complaints of the local fishermen, the government of Prussia allowed exterminating the “black strangers.”
Up to 1978, the grand cormorants were very rare guests on the coast of Lithuanian and the Curonian Lagoon. Later in these regions only single birds can be met from time to time, mostly during the period of spring and autumn migration.
Another “wave” of cormorants reached Juodkrante during 1974 - 1978. Non-hatching birds were observed in various wide open spaces of the Lagoon during various times of year. Quite promptly the black birds settled beside the herons.
Gradually, the herons were forced to give up the biggest part of their nests to the invaders, and in 1995 the lowest number of hatching herons was registered.
Nowadays, two settlements – of herons and cormorants – exist alongside each other. According to 2002 record data, 500 couples of grey herons and 2,000 couples of grand cormorants hatch here. The cormorants had started to build nests in 1989, the curve line of their plurality increases, and only the future will show when it is going to stabilize and what the consequences of their competition are going to be. Cormorants and herons are protected by the laws, therefore, there are no discussions going on concerning artificial decrease of their quantities.
Presently, cormorants are quite common birds, and their plurality in the Lagoon increases constranly. Local fishermen and foresters are dissatisfied because of the damage made by the mentioned birds.
Prepared according to Gediminas Grazulevicius and Dainius Elertas (Authority of the National Park of the Curonian Spit)