LEBRET T (1964) Black-crowned Night Heron and the Delta Plan. LIMOSA 37 (3): 277-298.

Black-crowned Night Heron Nycticorax nycticorax It is time that we will draw up the balance. The following items should therein to be incorporated. Negative 1. The Kwak for his fishing technique used in most cases shallow water with solid soil and not too dense vegetation. 2. In some European areas where numerous slam prevent, identify these three factors significantly the landscape in which the species collects its food. 3. In the Biesbosch will result from the implementation of the Delta Plan tides disappear and the landscape will therefore referred to under 2 factors gradually lose. The position of the soart shall be to in this area therefore less favorable. Positive 4. Frogs in the southern countries are important prey of Kwak. They will in the Biesbosch probably increase sharply after 1968. 5. The Kwak shows except under 1 fishing method outlined also from branches hanging over the water, from reeds and reed grass and forests from floating pieces of wood to fish. These positions will be in the Biesbosch after 1968 also numerous voarkomen. Whether they are numerous enough and on the duration will remain, it is impossible to say. I would therefore like to do the following suggestions for managing the Biesbosch reserves of the State Forest. A. Expanding the opportunities for the under 5 above beschreyen fishing method. 1. Currently there are leaching from the banks in many places in the Biesbosch reserves overhanging tree branches above the creeks. If this event of the loss of the tide at the time threatening to die or for other reasons disappear, then it is to be recommended a large number of willow cuttings horizontally and low over the water to legs. Also alder would probably be able to borrow this. 2. The tide floats in the Biesbosch still everywhere around wood. This will certainly decrease. Ret explain floating beams would like to recommend are. Especially combinations of in the form of a T, L, X, or R are to be recommended as they are not to their axis. B. Biotoop-development in the direction of a landscape as well as in the under 1 above form. 1. By underwater cutting reeds etc. at shallow depths (25-30 cm) would be a more open swamp land arise, which corresponds to that which the slam in the foreign food biotopes. Where the basis permitting, with horses grazing would be advisable. 2. Water depth and soil strength will be the actual Biesbosch Landscape are difficult or impossible to influence their development. Wei was in the Biesbosch Polders that part of the reserve, the water level can be increased, making the wealth of fish and frogs would increase. *) I ontveins me that the measures set out in B and costly seem revolutionary, two reasons for waiting. Yet it would I want to warn against. Let us, conservationists, Kwak show our appreciation for two things. Firstly, is the species in spite of the ill-treatment in the nineteenth century, as a breeding bird returned. Secondly, the presence of our unique, because northern colony of the species helped in the fight for the preservation of the Biesbosch. We can not second the cause of his departure!

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