CONSERVATION OF MARINE BIRDS IN THE DANISH MONARCHY 



271 



third of the West European Flyway popula- 

 tion passes Denmark in the fall. Possibly 

 some of the surface-feeding ducks listed in 

 Table 2 for January 1973 were recorded in 

 fresh water and not from the seas, but at the 

 time the census was taken most freshwater 

 lakes were frozen and, therefore, unavailable 

 for water birds. 



These breeding seabirds and the off-season 

 visitors do not constitute the total population 

 in Danish waters. Large numbers also occur in 

 summer as nonbreeding birds; most are in two 

 categories: (1) several hundred thousand pre- 

 adult (up to 4-5 years of age) gulls (mostly 

 great black-backed, herring, and lesser black- 

 backed gulls), which feed inshore or at the 

 coast, and (2) large concentrations of water- 

 fowl that carry out a molt migration in 

 Danish waters, particularly in shallow areas. 

 Black scoter (Melanitta nigra), velvet scoter 

 (M. fusca), common eider, and whooper swan 

 are especially numerous, totaling hundreds of 

 thousands of individuals, and probably con- 

 stituting the majority of the European molt- 

 ing populations of these species. Less 

 numerous, but still totaling thousands of 

 molting birds, are sheld-duck (Tadorna 

 tadorna), common goldeneye, red-breasted 

 merganser, and possibly some other diving 

 ducks. About 3,000 surface-feeding ducks of 

 various species, most of which undoubtedly 

 are local breeding birds undergo wing molt in 

 Danish waters. Comprehensive descriptions 

 of the molt migration, particularly in Den- 

 mark, were published by Salomonsen (1968) 

 and Joensen (1973a, 1974). 



It may then be concluded that very large 

 numbers of seabirds are found in Danish 

 waters in all periods of the year; most feed in 

 the inshore zone and some offshore, but none 

 in the pelagic zone. 



Increase of Seabirds 



Seabirds are affected by several factors re- 

 lated to human activities, most of which pose 

 a threat to them and will eventually reduce 

 their numbers. Some factors, however, tend to 

 increase bird numbers, like climatic changes 

 which, as reported by Salomonsen (1963), have 

 given rise to the immigration to Denmark of 

 great cormorant (in 1938); eared grebe, Podi- 



ceps nigricollis (about 1870); red-crested 

 pochard, Netta rufina (1940); common 

 pochard, Aythya ferina (about 1860); tufted 

 duck (about 1900); and common murre (1929). 

 They all still breed in Denmark, having more 

 or less increased in number. 



Another reason for increases of certain 

 species is legal protection. Among protected 

 seabirds are the sheld-duck, which has been 

 completely protected since 1931, and particu- 

 larly the mute swan, of which only 2 or 3 pairs 

 were breeding in Denmark when the species 

 was completely protected in 1926. Since then, 

 mute swans have increased enormously, 

 reaching at least 2,740 pairs in 1966 (Bloch 

 1971:43), of which large numbers were breed- 

 ing colonially on small islets of boulders or on 

 sand reefs off the coast (Bloch 1970:152). The 

 gannet has also increased considerably as a 

 fall visitor since about 1945, apparently due 

 to protection in England and other countries. 



Finally, some gull populations have in- 

 creased in size because of an increase in the 

 food supply, consisting especially of wastes 

 from commercial fisheries and garbage 

 dumps. In Denmark, this unnatural food 

 source has caused an enormous increase since 

 about 1925 in herring gulls (from less than 

 500 pairs to 60,000 pairs), lesser black-backed 

 gulls (all three subspecies, fuscus, inter- 

 medius, and graelsii have immigrated to Den- 

 mark), and great black-backed gulls (immi- 

 grated to Denmark in 1930). Improved waste 

 disposal practices in recent years have not yet 

 offset the rate of growth of these gull popula- 

 tions. The increase of common eiders, which 

 also started in about 1925, is probably related 

 to the increases in the larger gulls. 



Decrease of Seabirds 



A variety of factors tend to reduce the num- 

 bers of seabirds. The most important ones are 

 outlined below, with comments on what has 

 been done or what is expected to be done to re- 

 duce the impact of these activities on seabirds 

 and protect this endangered resource. 



Shooting of Seabirds 



The shooting of seabirds in Denmark is con- 

 siderable, because the seabirds are extraordi- 

 narily numerous, and the number of sports- 



