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Titre :	Barn Swallow studies at a Danish farm
Auteurs :	Peder V. Thellesen, Auteur
Type de document :	Article
Dans :	Dansk Ornitologisk Forenings Tidsskrift (94(1) 2000)
Article en page(s) :	5-11
Langues:	Anglais
Résumé :	A population of Barn Swallow Hirundo rustica was monitored during 1971-1998 at a farm in Hjortkaer, southwestern Jutland (55degree32'N 8degree43'E). The population size was 13-29 pairs (Fig. 1). The proportion of pairs laying a 2nd clutch was 68% (Fig. 2), slightly more than reported in other Danish studies. A total of 884 broods were recorded during the study period, and the number of young was determined in 860. The average size of 510 1st and 348 2nd broods was 4.37 and 3.93 young, respectively, at the time of ringing (Table 1). The average number of young per pair was 7.1. Local recoveries or controls of ringed young indicated that the juvenile swallows left the breeding site about three weeks after fledging (Fig. 5). A total of 93 birds returned to the farm (or the near surroundings) after one or more winters. As a proportion of those ringed, the returning birds comprised 0.8% of the nestlings, 1.8% of the fledged young and 20% of the adults. Only three ringed birds were reported from other countries (Switzerland, Spain, Morocco). A bird ringed on Corsica in spring was found breeding in Hjortkaer later in the same year. The development of the population was similar to that found in other Danish studies, particularly the country-wide point-count program (Fig. 6), indicating that annual fluctuations in the Danish swallow population are probably caused by prevailing conditions along the migration routes and in the winter quarters. A negative long-term trend in the Danish point-count index, on the other hand, is primarily an effect of changing agricultural practices in Denmark.

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