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Description
Millions of birds migrate each year between breeding grounds and overwintering areas. Migration behavior is influenced by a number of factors: day length, physiological and genetic factors, the magnetic compass, population dynamics, and by weather and climatic conditions. Historical and current data on avian migration are of broad scientific value. Most of the information on avian migration is presented in the form of summary statistics (e.g., duration of migration, number of individuals, trend line over years) in published studies, but original data sets are not readily available. Here, we describe the first open-source archive on visible diurnal spring migration in Central Europe. The database comprises the records of a systematic field study, which covers 35541 records of migrating birds for more than 138000 specimens of 96 species. Data were collected during the spring periods of 1984, 1985, and 1986. Bird census was conducted at the tip of the Höri peninsula in Lake Constance, Germany (north of the Alps: 47°41'49.11" N, 9°00'21.52" E). Migrating birds were counted from the beginning of March to the beginning of May each morning using fine-grained 15-min intervals. Flock size, migration heading, and weather conditions are provided for each species, e.g., for the European Chaffinch Fringilla coelebs. In all three years we found evidence that Chaffinches ceased to migrate to northeastern and eastern directions at the end of the observation period. The migration pattern of two thrush species (Turdus merula and T. viscivorus) is also presented in more detail. Turdus merula had its migration peak always early in the morning, whereas migration of T. viscivorus was recorded from the early morning onward, with a peak at late morning to noon. Migration records are also documented for species that are generally believed as resident birds in the inland of Central Europe (e.g., Streptopelia decaocto, Parus palustris, Certhia brachydactyla, Pica pica). Our archive might be of significance for studying patterns of daily migration, e.g., the effect of weather on spring migration intensity and for methodological studies on the same issue.
Key words: bird migration; Bodensee (Germany); Höri peninsula (Germany); Lake Constance (Germany); spring avian migration.
