LENSINK R, VAN TURNHOUT, C., BAKHUIZEN JJ, BOELE A, VAN DONGEN R, FOPPEN R, HULSEBOS B, LANJOUW R, RADEMAKER J & WOUDA S (2023) Increase and expansion of Middle Spotted Woodpecker Dendropicos medius in the Netherlands in 1995-2020: a textbook example of an invasion. LIMOSA 96 (1): 2-16.
The Middle Spotted Woodpecker re-established itself
as a breeding bird in the Netherlands in 1995, after
decades of absence and only a handful of confirmed
breeding cases earlier in the 20th century. This was
the start of a process of fast increase and expansion.
In 2020 the population is estimated at 1900-2100 pairs,
breeding in 11 of the 12 Dutch provinces, whereas
colonisation has not yet come to an end.
The first part of the colonisation occurred in the
southeast of the country (Limburg), near the German
and Belgian border. From 2004 onwards breeding
was noted in the east of the Netherlands (Twente,
Achterhoek), and gradually other regions in the south
and east were occupied (Fig. 2). Around 2010 the
species reached the coastal region. In the first years
after initial establishment increase and expansion
were relatively slow, but between 2002 and 2006 it
accelerated. Thereafter, the speed of colonization
slowed down again. Between 1995 and 2020 population
growth averaged around 10% per year and the rate
of range expansion 6.4 km/year. Between 2002 and
2006 increase and expansion were twice as high. Most
pairs breed and highest densities are reached in old
broadleaf forests with a strong dominance of Oak
species. Densities in the south (2 pairs/10 ha) seem to
have stabilized, whereas in the east these are higher (4
pairs/10 ha) without any signs of saturation. Recently
also broadleaved woodlands dominated by other
tree species than Oak were occupied, as well as small
woodlots and broad, old hedgerows.
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