De stand van de ooievaar, Ciconia c. ciconia (Linné), in Nederland in 1950 (The status of the White Stork in the Netherlands in the year 1950)

For many years in succession countings of the breeding number of white storks (Ciconia ciconia) ir the Netherlands have been performed by F. HAVERSCHMIDT. lis observations procure data up till the year 1946. As the decreasç or the white stork as a breeding species appeared to be rather alarmiug during recent years, a complete census of this species was carried out in the year 1950 by the State Forestry Service in the Netherlands, the results of which are given here. A second census will be performed in 1955. As late as in the 19th century the white stork was a common breeding species in the Netherlands (TEMMINCK, SCHLEGEL), but a sudden decrease in numbers has been recorded in 1857; a previous noticeable decrease was recorded in 1769. The first census of nests of the white stork was made in 1929. During that year 209 nests could be recordecf. In 1934 there were 273 recorded nests. In 1939 this number was 312. A slight increase in number was noticeable. In later years no complete census was performed anymore, but is seems that the year 1940 was a good year for the white stork. From 1941 to 1945 a serious decrease in the number of occupied nests occurred, the total number falling down below that of 1929, being about 150 r 160. All data published about special areas, controled after 1946, are used in this report. The census of 1950 was performed with the aid of many volunteers, Ornithologists, policemen, local authorities and many others cooperated all over- the country, making the data remarkably complete. Some new nests were recorded, but more than 230 nests, recorded as occupied by HAVERSCHMIDT appeared to be uninhabited. If the census of 1950 embodies any inaccuracies this may be by some nests being overlooked. The error is estimated, however, to be smaller than 5%. The results have been arranged in tables according to the provinces. Every nest is numbered. The numbers given by HAVERSCHMIDT are compared with the numbers of our census 1950, and with the numbers of previous years, as far as those are known. Nests marked 4- means that the nest was occupied by one bird only. The tables clearly show that the total number of occupied nests has seriously decreased since the last complete census. In fact the number fell down to 85 occupied nests. Compared with 1939, a decrease of the number of young of 76% and of the number of breeding pairs of 73% was calculated. The future of the white stork as a breeding bird in the Netherlands seems to be rather precarious. Statistical calculations on the population size of the white stork in the Netherlands, based on the data published in this paper, will appear in a future issue of this series.