114
H.Karup
observed in the baseline period of 1993-1995 (National Environmental Research Institute 1997).
The monitoring cruises for the 199511996 herring migration season showed concentrations of herring in the 0resund in October which corresponded to the concentrations which were found in the autumn months during the baseline studies in the period
1993-1995, while the monitoring cruises in March and April 1996 showed slightly higher
concentrations than during the baseline studies in March and April 1994 and 1995. These
higher concentrations in the spring of 1996 point to a later herring migration out of the
0resund owing to the very cold winter of 1995-1996. The concentrations still show,
however, that the herring made their usual migration out of the 0resund (Danish Ministry of the Environment and Energy, Danish Ministry of Transport, KSO 1997a).
For the 199611997 herring migration season two cruises took place in September!
October and November. Another two cruises are planned for the spring of 1997. The
first cruise in autumn 1996 showed the concentrations of herring to be slightly different to what was expected in relation to the concentrations found during the baseline
studies in 1993-1995 and monitoring in 1995. By the second cruise in the autumn of
1996 the concentrations were back to the expected levels, however.
In 1996, studies of overwintering and moulting mute swans were carried out. The
highest number of swans in the moulting period, 1500 individuals, was recorded in
early August, which means that the decline observed in the period 1993-1995 continued
in 1996 (National Environmental Research Institute 1997a). The decline can presumably be attributed to high mortality in the period January-February 1996, which was
probably caused by the harsh winter and ice sheet, and it is highly likely therefore that
it was not caused by the construction work. It can be added that the number of moulting swans along the west coast of Scania in July! August was also lower than before,
while the number of swans on Saltholm (approx. 2300) in March 1996 was the highest
since 1993 (National Environmental Research Institute 1997).
Counts of resting migratory birds on Saltholm in September and October 1996 produced a smaller number of surface-feeding ducks in relation to previous years, presumably because of very dry conditions on the island. The number rose substantially
following rain in late October and early November, when the numbers were very similar to those in the preliminary studies. The number of waders showed a similar development (National Environmental Research Institute 1997).
The analyses of the distribution of eiders, greylags and mute swans on Saltholm in
1996 showed that there had been changes in relation to previous years. In all cases there
were fewer birds in the immediate area of the alignment and more birds in the areas
east, north and north-west of Saltholm. It must therefore be judged very probable that
this redistribution is due to disturbances caused by the construction work (Fig. 10.3).
As far as all three species are concerned, however, there were still substantial numbers
seeking food in and close to the immediate area itself. Subsequent studies showed that
the eiders completed their breeding cycle without problems, and that the physical condition of the geese and swans at the end of the moulting period was no worse than in
previous years. The birds were therefore able to fmd sufficient food by using alternative
areas further away from the construction work (National Environmental Research Institute 1997).
The overall effects on the birds on Saltholm in 1996 can therefore be characterized
as being at the lowest possible level. Thus, it can therefore be concluded that there were
H.Karup
observed in the baseline period of 1993-1995 (National Environmental Research Institute 1997).
The monitoring cruises for the 199511996 herring migration season showed concentrations of herring in the 0resund in October which corresponded to the concentrations which were found in the autumn months during the baseline studies in the period
1993-1995, while the monitoring cruises in March and April 1996 showed slightly higher
concentrations than during the baseline studies in March and April 1994 and 1995. These
higher concentrations in the spring of 1996 point to a later herring migration out of the
0resund owing to the very cold winter of 1995-1996. The concentrations still show,
however, that the herring made their usual migration out of the 0resund (Danish Ministry of the Environment and Energy, Danish Ministry of Transport, KSO 1997a).
For the 199611997 herring migration season two cruises took place in September!
October and November. Another two cruises are planned for the spring of 1997. The
first cruise in autumn 1996 showed the concentrations of herring to be slightly different to what was expected in relation to the concentrations found during the baseline
studies in 1993-1995 and monitoring in 1995. By the second cruise in the autumn of
1996 the concentrations were back to the expected levels, however.
In 1996, studies of overwintering and moulting mute swans were carried out. The
highest number of swans in the moulting period, 1500 individuals, was recorded in
early August, which means that the decline observed in the period 1993-1995 continued
in 1996 (National Environmental Research Institute 1997a). The decline can presumably be attributed to high mortality in the period January-February 1996, which was
probably caused by the harsh winter and ice sheet, and it is highly likely therefore that
it was not caused by the construction work. It can be added that the number of moulting swans along the west coast of Scania in July! August was also lower than before,
while the number of swans on Saltholm (approx. 2300) in March 1996 was the highest
since 1993 (National Environmental Research Institute 1997).
Counts of resting migratory birds on Saltholm in September and October 1996 produced a smaller number of surface-feeding ducks in relation to previous years, presumably because of very dry conditions on the island. The number rose substantially
following rain in late October and early November, when the numbers were very similar to those in the preliminary studies. The number of waders showed a similar development (National Environmental Research Institute 1997).
The analyses of the distribution of eiders, greylags and mute swans on Saltholm in
1996 showed that there had been changes in relation to previous years. In all cases there
were fewer birds in the immediate area of the alignment and more birds in the areas
east, north and north-west of Saltholm. It must therefore be judged very probable that
this redistribution is due to disturbances caused by the construction work (Fig. 10.3).
As far as all three species are concerned, however, there were still substantial numbers
seeking food in and close to the immediate area itself. Subsequent studies showed that
the eiders completed their breeding cycle without problems, and that the physical condition of the geese and swans at the end of the moulting period was no worse than in
previous years. The birds were therefore able to fmd sufficient food by using alternative
areas further away from the construction work (National Environmental Research Institute 1997).
The overall effects on the birds on Saltholm in 1996 can therefore be characterized
as being at the lowest possible level. Thus, it can therefore be concluded that there were