Kuifleeuweriken Galerida cristata op hun retour

In this paper population changes in the Crested Lark in The Netherlands are described. In the first half of the 20th century the species must have been fairly numerous, especially on the sandy soils in the South and East of the country; it bred in the dunes and built-up areas in the West as well. In the 1970s and 1980s a severe decrease was noted in many areas (figure 1 for a comparison of numbers in the 1970 s and 1980s; in black the remaining part). In 25 study-areas numbers decreased from 622 tot 85 territories, a 86% decrease. In some intensely studied plots a continuing decrease took place during the whole survey period (figure 2). On a national level the breeding population de- creased from 3000-5000 pairs in 1973-1977 to 1000-2000 in 1985-1986 and 400-450 in 1990- 1991. Regional numbers for 1985-1986 and 1990- 1991 are given in figure 3. At the moment, Crested Larks have deserted large parts of the country (figure 4). The species has maintained relatively well in some coastal areas in the West of the country, especially in or near dunes. On a European level Crested Larks are still numerous in the southern half of the continent (figure 5) but population developments are disquieting. In Northern and Western Europe a very strong decrease is described, leading to extinction in some countries. In Central Europe and in parts of Southern Europe a less severe but noticeable decrease is reported, and only in parts of Southeast-Europe numbers are known to be stable (figure 6). In the past, climatic changes (less severe winters) have been held responsible for the increase in numbers and colonization of new areas in the 18th and 19th centuries. Although examples of heavy mortality in severe winters are known from The Netherlands, there is no evidence that winter conditions have been responsible for the quick and heavy decline of the Dutch breeding population in the 1970s and 1980s (the severe 1978/1979 and 1984/1985 – 1986/1987 winters had no impact on breeding numbers in study plots; figure 2). Although other climatic factors cannot be excluded, it is much more likely that habitat factors have caused the sharp decrease. In heatherland, sandy inland dunes and on arable land, habitats that held small numbers of Crested Larks until the 1960s or 1970s, the spe- cies has probably disappeared as a consequence of overgrowing of bare grounds (heather) and intensification of land use (arable land). In town and villages that held good numbers until the 19705, some adverse developments have taken place. Building activities have diminished after a boom in the 1960s, a change took place from well-spaced low-rise building areas and blocks of flats to low-rise building with less open space. Besides this, in older urban areas fallow lands have been built up or are permanently disturbed by recreational activities, cats and dogs. Perhaps some other factors may have contributed as well, such as food shortage caused by (aerial) pollution and the use of herbicides as well as casualties by increased traffic. As these adverse factors will probably have an even greater impact in the future, and as a recolonization of suitable breeding habitats becomes unlikely (given the declining populations in surrounding countries and the weak dispersion in these species) it is to be expected that the Dutch breeding population of the Crested Lark will decrease further in the next years.