Aves, p�le ornithologique de Natagora

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Aves, 36/1-3 | 1999 | 113-126

  The Red-backed Shrike (Lanius collurio) in The Netherlands : showing one's paces.
Van Dijk, A.J& Hustings, F.

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Article summary

At the beginning of the 20th century the Red-backed Shrike was a widely distributed and fairly common breeding bird in The Netherlands, with an estimated breeding population of at least several thousands pairs (see figure 1 for some areas regularly mentioned in the text). Population numbers seem to have fluctuated. In the 1920s and 1930s a local decrease was recorded, followed by an increase in the 1940s. From the 1950s on, a nationwide and devastating long term decrease set in, resulting in a breeding range contraction (figure 2) and severely depleted breeding numbers. At its nadir, around 1985-86, the Dutch breeding population consisted of only 80-140 pairs (table 1). Since then, numbers have slightly recovered to some 210-230 pairs in 1995-96, mainly restricted to the easternmost parts of the country (figure 3). This partial recovery is mainly due to a strong increase in breeding numbers in the Bargerveen, a peat moor reserve (2000 ha) in the province of Drenthe, in the NE-Netherlands. Numbers here have grown from 9 breeding pairs in 1982 to 145 pairs in 1996 (figure 4). In most other areas numbers have continued to decrease, to the point of near-extinction (e.g. in the coastal dune area and on the Wadden islands, in former times important breeding areas). In a few inland areas, almost exclusively situated along the eastern border or at the Veluwe (central Netherlands), numbers have stabilised and in some cases small numbers have reoccupied, sometimes only temporarily, area lost in the past. The strong decrease of the Dutch breeding population in the past has probably mainly been caused by agricultural changes resulting in habitat loss and food shortage. The increasing numbers in the Bargerveen coincide with the start of habitat management with the purpose of peat moor regeneration and resulting in great insect diversity and abundance. A row of rather dry and warm summers may have been favourable and contributed to the increase (figure 5). The future chances of Red-backed Shrike in farmland in The Netherlands are thought to be marginal, although small scale experiments in farmland reserves have sometimes resulted in a come-back of the species as a breeding bird. In nature reserves, chances are thought to be better. The Bargerveen example proves that creation of mosaic like habitats with all kinds of variations in soil moisture and vegetation succession may be promising. Feeding conditions seem to be one of the key-factors for establishment of Red-backed Shrike populations at the moment. As a consequence, restoration of insect diversity will be of utmost importance.