Timmerman A. & Mörzer Bruyns M.F. (1959) Het broedseizoen van de Kievit, Vanellus vanellus, in 1957. ARDEA 47 (1-2): 87-98

geen Nederlandse samenvatting beschikbaar op internet The breeding season of the Lapwing, Vanellus vanellus in 1957. The mild spring of 1957 stimulated the Lapwing in the Netherlands in such a way that egg-laying started very early in the season (first eggs found about 10th March, normal roughly 24th March). Owing to this, during the period that in the Netherlands the collecting of Lapwing eggs is allowed (till 12th or 19th of April) an exceptionally large number of eggs were taken and brought in for sale. Some ornithologists expressed their concern regarding an eventual unfavourable influence of this exceptional high toll for the breeding success of the Lapwing in 1957. Inquiries were made concerning the numbers of eggs brought in for sale in 1957 and 1958 (fig. 1). Although there was a slight decrease of numbers in the last few days of the collecting period this decline was not alarming. Furthermore an enquiry was made regarding the ultimate breeding results of the Lapwing in the Netherlands in 1957 in general. These results were extremely sati factionary. Data from 56 well known breeding areas known as good Lapwing grounds became available and almost everywhere 1957 had been a very good breeding season. The result of the taking of eggs was nowhere apparent. Average numbers of eggs collected at carefully supervised areas, chiefly in FryslGn, are shown in fig. 2. In the areas A, D, E, F and H there was only information about numbers during the collecting period, from 3 areas (B, C and G) also numbers are known from the first weeks after the collecting period. The constancy of productivity in these areas and the increase after the closing of the collecting period are shown in the graph and in curve 1. Curve 2 indicates the average numbers of eggs present in 6 breeding areas (I-N) were no egg-collecting was permitted. From that curve it is evident that many Lapwings start breeding later than 19th April, after the closing of the collecting period; this is in accordance with the experience of many field-ornithologists. In spite of the early season and the taking of many eggs, the Lapwing in 1957 was a successful breeder. This is completely in accordance with the results of the research done by Klomp (1951). Klomp proved that Lapwings are able to breed successfully even after having lost 4 complete consecutive clutches. In 1957 most Lapwing pairs cannot have lost more than 2 or 3 clutches. Low temperatures in April and May 1957 were favourable for the breeding of the Lapwing, as on account of this reason the haymaking season only started after the period that most Lapwing eggs were hatched.