RENSSEN TA (1988) Re-introduction of the Raven Corvus corax in the Netherlands. LIMOSA 61 (3): 137-144.

Common Raven Corvus corax After a sharp decline in numbers during the early decades of the 20th century, the last Raven was found breeding in 1944 (fig. 1). In 1966, a re-introduction project was started. During 1966-78 Ravens were imported from FRG (39), GDR (75), and Switzerland (2) (appendix 1). The imported Ravens were partly kept in cages and partly released (appendix 1). Most young hatched in the cages were released (appendix 1). In 1976, the first free-living breeding pairs were observed (fig. 2). After a few years of increasing numbers, the population crashed (fig. 2). Since 1983-84, a strong increase takes place up to 17 breeding pairs in 1988. Most Ravens breed on the Veluwe, a large area with coniferous and deciduous forests, and heather fields. One pair was recorded in the dunes (1979) and one on the Utrechtse Heuvelrug (1976-88). Since 1980, solitary Ravens are recorded elsewhere in the country. In the first years, the breeding success was quite low, but improved with time (appendix 2). In 1976-88, 87 pairs raised 164 young, average 1.89jpair (s.d. 1.57). For the successful pairs (68%), the average was 2.78 young (s.d. 1.07). At present, the population comprises nearly exclusively of birds born in the wild. The decline in 1980-81 probably marks the extinction of introduced birds at a moment the numbers of free-born Ravens were not yet large enough to fill the gap (fig. 3, appendix I). In the Netherlands the Raven feeds, among other things as afterbirths of sheep and deer, and artificial feeding sites for game, on insects and their larvae, carrion, and rubbish. Around 1945, Raven only remained in Schleswig-Holstein, Poland, eastern Czechoslovakia, in the higher Alps, and along the western coast of France. After strong protective measures were taken, the species re-occupied several parts of western Europe (fig. 4). The re-introduction in the Netherlands was the first in western Europe, and was followed by successful ones in Belgium and FRG.

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