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Institut de recherche pour la conservation des zones humides méditerranéennes

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Titre :	Responses of Middle Spotted Woodpecker Dendrocopos medius to play-back in course of population surveys in Schleswig-Holstein (North Germany)
Auteurs :	Rolf K. Berndt, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (130(2) 2009)
Article en page(s) :	91-98
Résumé :	In 2001 we started to use tape lures to survey Middle Spotted Woodpecker in Schleswig-Holstein (North Germany). From the very beginning we noted type and intensity of responses of the birds. The following frame conditions should be considered: the type of lure is not of importance, but the play-back volume should be approximately the same as of the natural calls. The distance between play-back points should not exceed 150 m, since otherwise birds could easily be omitted. According to the regional weather conditions in Schleswig-Holstein the period form mid-March to early May is recommended for systematic surveys. According to our data, in the period from March to May approximately 85% of the woodpeckers do respond to the tape lures. The most frequent response is the alarm call (rattle; 54% of responses). The courtship call (squawking) is only as half as frequent (21%). A substantial part of the birds approaches the tape lure in flight. The use of tape lure is an efficient method to get proper population estimates, but two disadvantages have to be considered: Even in the optimal period, 10-20% of the birds may not respond. Furtheron, both sexes are able to use the same calls (rattle and courtship call) and may respond from different positions within the same territory; this may lead to overestimates. It is not possible to estimate more precisely the proportion of such cases, but I would suggest reducing initial estimates by 25%. Population estimates for single sites should consider these potential errors. TO estimate the population size of a larger area (e.g. a federal state), numerous estimates for single forest tracts should be combined. To assess the longterm population trend we have to know method and precision of former surveys in detail. There are indications that population estimates resulting from repeated visits with tape lures are roughly as twice as high as from surveys without play-back use.

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