BRAAKSMA S (1962) Distribution and habits of the Corncrake Crex crex. LIMOSA 35 (3): 230-259.

An investigation concerning the distribution of the Corncrake in the Netherlands, during 1947-1960, made by the State Forest Service, with the aid of about 200 cooperators, proved that the number of breedingpairs of this species probably varies at present from about 40 till 80. One may conclude, that the number of breedingbirds has seriously decreased, mainly owing to earlier mowing of the grass, which forms their principal habitat. The cooperators gave information on at least 80 breedingcases disturbed by mowingmachines ... It seems likely, that an increasing number of Corncrakes settles at cornfields and other habitats, previously usually not accepted by this species. In grasslands Corncrakes seem to prefer fields which have been flooded in winter. Therefore a remarkable number of breedingcases has been ascertained in the neighbourhood of rivers and lakes. As the species is practically unknown to many dutch ornithologists details have been given concerning the breedingbiology, the behaviour and the migration. With regard to the large fluctuations in the number of breedingpairs, the author suggests that in some years a sort of invasion of Corncrakes from elsewhere - perhaps even from central or east-european countries - might occur. If this is true, the possibility arises, that there might be a correlation between the invasions and long periods of dryness in these countries. Out of this point of view it is interesting to note, that a bird ringed in Hungary as a nestling on the 12th of July 1930 has been recovered in Holland on the 25th of June 1931, in a regular breeding area of Corncrakes. An investigation concerning the possibility of a correlation between the fluctuations in the number of breedingpairs and the amount of rainfall in our country during the first four months of the year has not led to any possitive result. In Holland the call of the Corncrakes appears to be heard mainly during the second half of May, June and the first half of July. With regard to the fact that callnotes sometimes have been heard in April, August or September, in places where Corncrakes usually do not breed, one may conclude, that the species sometimes calls on migration too. Regarding the serious decrease which has been ascertained in practically all european countries, the establishment of special breedingreserves seems to be the only way to assure the survival of the species. The reserves have to be founded at places where the Corncrakes still are regular breedingbirds. The structure of the reserves is to remain unchanged and no mowing is to be allowed before the 20th of July. Corncrake Crex crex

[free pdf] [dutch summary]