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Lukas Jenni

Wahl der Nahrungsgebiete von Bergfinken Fringilla montifringilla in Massenschlafplätzen.

2022

119

194–211

Key words
(von 1994 bis 2006 vergeben)

Schlafplatz, Nahrungsraum, Nahrungsgebiet, Verhalten, Schneedecke, Wind, Niederschlag, Wetter, Flugwege

Schlagwort_Vogelart
(wissenschaftlich)

Fringilla montifringilla

Schlagwort_Vogelart
(deutsch)

Bergfink

Schweiz, Basel-Landschaft, Luzern, Obwalden

deutsch

Abhandlung

Selection of foraging areas by Bramblings Fringilla montifringilla in mass roosts. – Bramblings are well-known for their huge flocks that gather in beech mast areas in roosts of several million individuals. This study examines with over 2000 observations in the area of three large roosts in the winters 1977/78 und 1982/83, (a) whether the amount of beech seeds was sufficient to feed millions of Bramblings for four months, and (b) how Bramblings select their daily foraging areas in the area of the roost. Bramblings flew up to 40 km or more to foraging sites. In this area of 5000–6000 km2, the supply of beech seeds was superabundant, and only a fraction of it was used by the Bramblings. The three roosts were not situated in the middle of the best beech mast areas, which usually were at higher elevations and were used most frequently, but at the edge or in the centre of several distant beechmast areas. The Bramblings used only one main sector for foraging per day, depending on snow cover and weather. Without snow cover in the best beechmast area, the Bramblings used these in good weather, but used protected valleys and areas far from mountains in bad weather. With snow cover in the best beechmast area, they used areas at lower elevation, and in bad weather they used the lowest and protected areas. When snow covered the lowest areas, Bramblings searched for food in villages and cities, and eventually left the roost. Hence, the best beechmast areas were used by all Bramblings so that the less rich beechmast areas were left for the days when snow covered the higher elevations. Apparently, Bramblings strive to minimize the risks due to bad weather during flight (collisions, prevention to reach the roost) by flying to protected foraging areas. The most likely function of such large roosts is discussed, namely securing food when snow cover increases and minimizing the risks during flight due to bad weather.