Changes in the breeding bird fauna of two southern German rural communities during recent decades — lost paradises? | Die Veränderung der Brutvogelfauna in zwei süddeutschen Dorfgemeindebereichen in den letzten fünf bzw. drei Jahrzehnten oder: verlorene Paradiese?

In the regions associated with two rural communities (Möggingen — site of the Vogelwarte Radolfzell — and Billafingen — the author's residence, both near Lake Constance) the changes in the local avifauna have been followed for 5 and 3 decades respectively, by means of continuous observation, repeated population assessments, diary notes etc., for Möggingen also in quantitative detail. The results, summarized in Tables 1 and 2, are based on extensive species descriptions with source citations, which are available at http://www.do-g.de/journals or from the author.In selected study areas around Möggingen (ca. 4 km²) in the course of 50 years 110 species of breeding birds have been detected, and around Billafingen (ca. 8 km²) in 30 years 84 species; of these, 89 and 74 respectively have been (almost) regular breeders. Changes over the study period are measurable: of the (almost) regularly breeding species 18 (21 %) and 14 (19 %) have disappeared, while 12 (14 %) and 5 (7 %) now breed irregularly or hardly at all. Of the 56 regularly breeding species that remain near Möggingen, the populations of 20 have clearly declined, 32 are stable, only 4 have increased; the values for Billafingen are 7 out of 51 declined, 41 stable and 3 increased. Only 8 and 3 new species respectively are now (at least for the time being) breeding there.For the Möggingen study area it can be shown that the overall number of individuals has also shrunk considerably — from the original ca. 3300 to the present 2100 — and with it the total bird biomass — formerly ca. 240 kg, now 150 kg. This enormous and continuing loss of species diversity and individuals is attributable substantially to three factor complexes, which are discussed in detail: (i) destruction of habitats and deterioration of habitat quality, especially food supply, (ii) disturbances in the landscape and (iii) global climate warming. To arrest this deterioration towards an „increasingly Silent Spring” if possible, eight specific countermeasures are proposed: (i) political lobbying by organisations and the public, (ii) mobilisation of scientists, (iii) reorientation of basic research, (iv) enlisting the media, (v) more objective evaluation of successes, failures and influential parameters, (vi) up-to-date measures for protecting particular areas, (vii) establishment of a Management Group and (viii) intensification of conservation-oriented education.