CAUSES FOR THE DECLINE OF EUROPEAN SONGBIRDS - AN ANALYSIS OF THE MIGRATORY BIRD TRAPPING DATA OF THE METTNAU-REIT-ILLMITZ-PROGRAM

Trapping data of migratory birds collected 1974-1983 by the Mettnau-Reit-Illmitz-Program of the Vogelwarte Radolfzell were analyzed to understand the causes for population declines of European songbirds. Changes in breeding and wintering habitat were significantly correlated with population trends of the 34 species of songbirds; diet during the breeding season, migratory status and wintering area were not. Population declines of species inhabiting wetlands, open countryside and savanna were contrasted by stable populations of species inhabiting settlements and forests. As forests declined severely in the wintering regions of Africa the population declines could be attributed to habitat destruction on the breeding grounds.