Glutz von Blotzheim, U. N., P. Hauff & H. Kovacs
(* = Kurzbeitrag)
Vom Fels zum First – Zur langfristigen Entwicklung des im Oberwallis an Gebäuden brütenden Bestandes der Felsenschwalbe Ptyonoprogne rupestris und zur Dauer der Brutperiode.
(von 1994 bis 2006 vergeben)
Verbreitung, Arealausweitung, Bestandesentwicklung, Nistplätze, Gebäudebrüter, Brutperiode, Brutbiologie, Brutbeginn, Witterung, Schutzmassnahmen
Ptyonoprogne rupestris, Delichon urbicum
From rocky cliffs to buildings – distribution, increasing abundance and breeding season of Eurasian Crag Martins Ptyonoprogne rupestris in human settlements of the uppermost Rhone valley during the last thirty years. The Eurasian Crag Martin Ptyonoprogne rupestris is a xero-mountainous species reaching its northern boundary in the Alps and recently a little bit further north. Up to some 30 years ago it was nesting almost exclusively in rocky cliffs. The beginning of the continuous breeding of the Crag Martin on artificial sites in the Valais region has been described in several papers (Glutz von Blotzheim 2002, 2003, 2005 and 2008). In the 44 most regularly investigated parishes and hamlets the number of breeding pairs reached a first maximum (108 pairs) in 2004. That year followed the up-to-now warmest spring and summer ever registered, with an early start of egg laying and a high percentage of second broods. The following years showed an ongoing expansion of the breeding range (even Gletsch and Chandolin in 2010) and a trend of population increase, but the number of breeding attempts on buildings reached a new maximum (121 pairs) only in 2008. The rate of increase was lower than expected for three reasons: (1) a growing intolerance of owners of flats and houses towards House and Crag Martins, (2) the restoration of several buildings previously regularly occupied by Crag Martins and (3) unfavourable meteorological spring conditions (cold and wet weather) in 2009 and 2010. With regard to the increasing attempts to discourage the Crag Martins from buildings we should foster the understanding by the public of the changing nesting habit of this species, which is a consequence of population increase and our simultaneous rapidly growing offer of «artificial rocks» in the form of scattered, elevated buildings. If our hospitality in favour of Crag Martins does not improve, the changing nesting habit could develop into an ecological pitfall. The adoption of man-made nesting sites has nothing to do with urbanization as in the Common House Martin Delichon urbicum. Furthermore our observations give no support at all for colonial nesting as a consequence of social cohesion. Loose aggregations of nesting pairs are nothing else than the result of the availability of sheltered sites in natural or artificial cliffs with favourable nearby hunting areas. In 2011 the breeding season started earlier than ever before.
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