Ynglefugle i Vejlerne - Dansk Ornitologisk Forening

Maximum numbers from counts of all present Avocets
in the period April – mid May has generally been
in agreement with population estimates based on nest
counts in the breeding colonies (Fig. 52), but in 2002-03
much fever breeding pairs were mapped near the colonies
than counted earlier in the seasons. In 2002 1281
birds were recorded on April 10, the highest number
ever recorded at Vejlerne. Unfortunately the sluices were
opened inappropriately in breeding season this year, and
many of the shallow pools the Avocets use for breeding
dried up. Higher water levels generally attracts high
numbers of Avocets, and they settle to breed on islets and
channel banks with sparse vegetation, but only in years
with permanently higher water levels result in successful
breeding for most pairs.
The Avocet population in Vejlerne represents approx.
1% of the population breeding around the North Sea, and
2-7% of the Danish population of 4100-4600 pairs in the
mid-1990s. The reserve is an important breeding locality
for the species, especially when considering the site as
the northwesternmost larger breeding concentration in
Europe. If Vejlerne and especially Bygholmengen shall
continue to remain of national and international importance
for Avocets, it is of utmost importance to secure
high water levels and avoid sudden lowering of these during
the breeding season.
Ringed Plover is an uncommon breeder in Vejlerne,
probably because this wetland complex only offers few
suitable habitats for this true coastal shorebird. Østerild
Fjord is the only lagoon where it has been recorded annually
with up to 12 pairs. The total population in Vejlerne
has varied between 5 and 25 pairs (average 14),
and it is possible that the population has been overestimated,
i.e. some birds recorded as breeders could be
spring migrants.
Little Ringed Plover has not been mentioned in the historical
literature dealing with Vejlerne, and only late in
the period with the Field Observatory, birds began to be
observed in the breeding season, in conjunction with a
remarkable increase in the national population. Several
pairs have been recorded breeding in the vicinity of Vejlerne
in the 1990s, and in 2002-03 the species was recorded
breeding on the reserve proper (2-3 breeding attempts
both years). The pairs established territories at typical
"Ringed Plover habitat" with sparse vegetation.
Kentish Plovers bred along the sandy beaches of Limfjorden
near Vejlerne in the past. Some have also been
recorded in Vejlerne, but they probably never bred on
the reserve.
Lapwing. All accounts on the breeding birds of Vejlerne
prior to 1978 mention Lapwing as a common and numerous
breeder. In 1978-2003 the population has varied
considerably, but with an increasing trend (Fig. 54). The
largest population was recorded in the last four years covered
here, with more than 1000 pairs in 2001-03 and
1150 pairs in 2002. The population has been distributed
Breeding birds in Vejlerne 223
among several sites, with Bygholmengen being the most
important locality (37% of pairs recorded); other sites
with larger numbers are the meadows surrounding Vesløs/Arup
Vejle (18%), Østerild Fjord (10%), Tømmerby
Fjord (9%) and Læsvig (8%). The rest has been spaced
out in low densities over the rest of the immediate surroundings
of the reserve.
A correlation between the number of Lapwings at
Bygholmengen and the water level in May suggests that
Lapwing is one of the few species that respond negatively
on a high water level (Fig. 55). 2000-2003 however
represents a discrepancy from this pattern, with very
high numbers breeding despite a mid-range water level
on Bygholmengen (Fig. 55). Hence one must perhaps be
slightly cautious, and avoid to use the mentioned negative
correlation for management recommendations, until
more evidence has been compiled and analysed. A mechanism
behind the claimed correlation could be that
Lapwings spread out to many small temporary wetlands
in the surrounding landscape in wet springs, but gather
at Bygholmengen and other wet meadows of Vejlerne in
dry years, simply because the latter in such situations represents
the only suitable breeding habitat in the region.
It is likely that the exceptionally high populations in
2000-03 were caused by a simultaneous decline in the
lo cal fox population, due to an outbreak of sarcoptic
mange. The four years mentioned are among the ve years
with fewest records of foxes in Vejlerne (systematically
recorded 1985-2003), and several waders had their
highest populations in these same years. In support of
this is a strong negative correlation between an index
of the fox population and the Lapwing population at
Bygholmengen 1985-2003.
Vejlerne holds a very important concentration of
Lapwings representing between 2.5 and 4% of the estimated
Danish population of 30.000-45.000 pairs in
the late 1990s. It is of major importance that grazing of
the meadows in the reserve itself as well as in the vicinity
is maintained to the benet of Lapwings and other
breeding waders.
Dunlin. Reports on the breeding population prior to
1978 suggest that the species was common in the rst
half of the 20 th Century, but management changes after
1950 (drainage, fertilization and overgrowing of meadows
due to cessation of cattle-grazing) probably initiated
a long-term decline in Dunlin numbers around Vejlerne
as anywhere else in Denmark.
The mapped Dunlin population 1978-2003 has uctuated
(Fig. 56), and was largest around 1986-1990 with
140-155 pairs. Later the population declined, at rst rapidly,
but the last decade it seems to have leveled out.
Dunlins are difcult to count, and it is only counts and
numbers after 1986 that are truly comparable, because
they were mapped in June when females attend chicks.
Bygholmengen has been the single most important
site with 77% of all recorded pairs. The development in
this meadow's grazing pressure is probably an important
factor inuencing the population size, but even at the
core breeding area in Vejlerne, the short-grazed eastern